1208 lines
28 KiB
C
1208 lines
28 KiB
C
/* Linux-dependent part of branch trace support for GDB, and GDBserver.
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Copyright (C) 2013-2017 Free Software Foundation, Inc.
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Contributed by Intel Corp. <markus.t.metzger@intel.com>
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This file is part of GDB.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>. */
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#include "common-defs.h"
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#include "linux-btrace.h"
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#include "common-regcache.h"
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#include "gdb_wait.h"
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#include "x86-cpuid.h"
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#include "filestuff.h"
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#include <inttypes.h>
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#ifdef HAVE_SYS_SYSCALL_H
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#include <sys/syscall.h>
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#endif
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#if HAVE_LINUX_PERF_EVENT_H && defined(SYS_perf_event_open)
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#include <unistd.h>
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#include <sys/mman.h>
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#include <sys/user.h>
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#include "nat/gdb_ptrace.h"
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#include <sys/types.h>
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#include <signal.h>
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/* A branch trace record in perf_event. */
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struct perf_event_bts
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{
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/* The linear address of the branch source. */
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uint64_t from;
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/* The linear address of the branch destination. */
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uint64_t to;
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};
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/* A perf_event branch trace sample. */
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struct perf_event_sample
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{
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/* The perf_event sample header. */
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struct perf_event_header header;
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/* The perf_event branch tracing payload. */
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struct perf_event_bts bts;
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};
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/* Identify the cpu we're running on. */
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static struct btrace_cpu
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btrace_this_cpu (void)
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{
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struct btrace_cpu cpu;
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unsigned int eax, ebx, ecx, edx;
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int ok;
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memset (&cpu, 0, sizeof (cpu));
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ok = x86_cpuid (0, &eax, &ebx, &ecx, &edx);
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if (ok != 0)
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{
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if (ebx == signature_INTEL_ebx && ecx == signature_INTEL_ecx
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&& edx == signature_INTEL_edx)
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{
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unsigned int cpuid, ignore;
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ok = x86_cpuid (1, &cpuid, &ignore, &ignore, &ignore);
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if (ok != 0)
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{
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cpu.vendor = CV_INTEL;
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cpu.family = (cpuid >> 8) & 0xf;
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cpu.model = (cpuid >> 4) & 0xf;
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if (cpu.family == 0x6)
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cpu.model += (cpuid >> 12) & 0xf0;
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}
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}
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}
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return cpu;
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}
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/* Return non-zero if there is new data in PEVENT; zero otherwise. */
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static int
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perf_event_new_data (const struct perf_event_buffer *pev)
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{
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return *pev->data_head != pev->last_head;
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}
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/* Copy the last SIZE bytes from PEV ending at DATA_HEAD and return a pointer
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to the memory holding the copy.
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The caller is responsible for freeing the memory. */
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static gdb_byte *
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perf_event_read (const struct perf_event_buffer *pev, __u64 data_head,
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size_t size)
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{
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const gdb_byte *begin, *end, *start, *stop;
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gdb_byte *buffer;
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size_t buffer_size;
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__u64 data_tail;
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if (size == 0)
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return NULL;
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/* We should never ask for more data than the buffer can hold. */
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buffer_size = pev->size;
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gdb_assert (size <= buffer_size);
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/* If we ask for more data than we seem to have, we wrap around and read
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data from the end of the buffer. This is already handled by the %
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BUFFER_SIZE operation, below. Here, we just need to make sure that we
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don't underflow.
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Note that this is perfectly OK for perf event buffers where data_head
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doesn'grow indefinitely and instead wraps around to remain within the
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buffer's boundaries. */
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if (data_head < size)
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data_head += buffer_size;
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gdb_assert (size <= data_head);
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data_tail = data_head - size;
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begin = pev->mem;
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start = begin + data_tail % buffer_size;
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stop = begin + data_head % buffer_size;
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buffer = (gdb_byte *) xmalloc (size);
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if (start < stop)
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memcpy (buffer, start, stop - start);
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else
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{
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end = begin + buffer_size;
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memcpy (buffer, start, end - start);
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memcpy (buffer + (end - start), begin, stop - begin);
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}
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return buffer;
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}
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/* Copy the perf event buffer data from PEV.
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Store a pointer to the copy into DATA and its size in SIZE. */
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static void
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perf_event_read_all (struct perf_event_buffer *pev, gdb_byte **data,
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size_t *psize)
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{
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size_t size;
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__u64 data_head;
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data_head = *pev->data_head;
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size = pev->size;
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*data = perf_event_read (pev, data_head, size);
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*psize = size;
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pev->last_head = data_head;
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}
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/* Determine the event type.
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Returns zero on success and fills in TYPE; returns -1 otherwise. */
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static int
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perf_event_pt_event_type (int *type)
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{
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FILE *file;
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int found;
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file = fopen ("/sys/bus/event_source/devices/intel_pt/type", "r");
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if (file == NULL)
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return -1;
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found = fscanf (file, "%d", type);
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fclose (file);
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if (found == 1)
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return 0;
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return -1;
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}
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/* Try to determine the start address of the Linux kernel. */
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static uint64_t
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linux_determine_kernel_start (void)
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{
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static uint64_t kernel_start;
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static int cached;
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FILE *file;
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if (cached != 0)
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return kernel_start;
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cached = 1;
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file = gdb_fopen_cloexec ("/proc/kallsyms", "r");
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if (file == NULL)
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return kernel_start;
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while (!feof (file))
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{
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char buffer[1024], symbol[8], *line;
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uint64_t addr;
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int match;
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line = fgets (buffer, sizeof (buffer), file);
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if (line == NULL)
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break;
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match = sscanf (line, "%" SCNx64 " %*[tT] %7s", &addr, symbol);
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if (match != 2)
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continue;
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if (strcmp (symbol, "_text") == 0)
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{
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kernel_start = addr;
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break;
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}
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}
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fclose (file);
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return kernel_start;
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}
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/* Check whether an address is in the kernel. */
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static inline int
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perf_event_is_kernel_addr (uint64_t addr)
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{
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uint64_t kernel_start;
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kernel_start = linux_determine_kernel_start ();
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if (kernel_start != 0ull)
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return (addr >= kernel_start);
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/* If we don't know the kernel's start address, let's check the most
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significant bit. This will work at least for 64-bit kernels. */
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return ((addr & (1ull << 63)) != 0);
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}
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/* Check whether a perf event record should be skipped. */
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static inline int
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perf_event_skip_bts_record (const struct perf_event_bts *bts)
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{
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/* The hardware may report branches from kernel into user space. Branches
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from user into kernel space will be suppressed. We filter the former to
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provide a consistent branch trace excluding kernel. */
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return perf_event_is_kernel_addr (bts->from);
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}
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/* Perform a few consistency checks on a perf event sample record. This is
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meant to catch cases when we get out of sync with the perf event stream. */
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static inline int
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perf_event_sample_ok (const struct perf_event_sample *sample)
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{
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if (sample->header.type != PERF_RECORD_SAMPLE)
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return 0;
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if (sample->header.size != sizeof (*sample))
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return 0;
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return 1;
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}
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/* Branch trace is collected in a circular buffer [begin; end) as pairs of from
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and to addresses (plus a header).
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Start points into that buffer at the next sample position.
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We read the collected samples backwards from start.
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While reading the samples, we convert the information into a list of blocks.
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For two adjacent samples s1 and s2, we form a block b such that b.begin =
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s1.to and b.end = s2.from.
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In case the buffer overflows during sampling, one sample may have its lower
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part at the end and its upper part at the beginning of the buffer. */
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static VEC (btrace_block_s) *
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perf_event_read_bts (struct btrace_target_info* tinfo, const uint8_t *begin,
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const uint8_t *end, const uint8_t *start, size_t size)
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{
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VEC (btrace_block_s) *btrace = NULL;
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struct perf_event_sample sample;
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size_t read = 0;
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struct btrace_block block = { 0, 0 };
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struct regcache *regcache;
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gdb_assert (begin <= start);
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gdb_assert (start <= end);
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/* The first block ends at the current pc. */
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regcache = get_thread_regcache_for_ptid (tinfo->ptid);
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block.end = regcache_read_pc (regcache);
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/* The buffer may contain a partial record as its last entry (i.e. when the
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buffer size is not a multiple of the sample size). */
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read = sizeof (sample) - 1;
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for (; read < size; read += sizeof (sample))
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{
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const struct perf_event_sample *psample;
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/* Find the next perf_event sample in a backwards traversal. */
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start -= sizeof (sample);
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/* If we're still inside the buffer, we're done. */
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if (begin <= start)
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psample = (const struct perf_event_sample *) start;
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else
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{
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int missing;
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/* We're to the left of the ring buffer, we will wrap around and
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reappear at the very right of the ring buffer. */
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missing = (begin - start);
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start = (end - missing);
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/* If the entire sample is missing, we're done. */
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if (missing == sizeof (sample))
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psample = (const struct perf_event_sample *) start;
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else
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{
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uint8_t *stack;
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/* The sample wrapped around. The lower part is at the end and
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the upper part is at the beginning of the buffer. */
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stack = (uint8_t *) &sample;
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/* Copy the two parts so we have a contiguous sample. */
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memcpy (stack, start, missing);
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memcpy (stack + missing, begin, sizeof (sample) - missing);
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psample = &sample;
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}
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}
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if (!perf_event_sample_ok (psample))
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{
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warning (_("Branch trace may be incomplete."));
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break;
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}
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if (perf_event_skip_bts_record (&psample->bts))
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continue;
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/* We found a valid sample, so we can complete the current block. */
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block.begin = psample->bts.to;
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VEC_safe_push (btrace_block_s, btrace, &block);
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/* Start the next block. */
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block.end = psample->bts.from;
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}
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/* Push the last block (i.e. the first one of inferior execution), as well.
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We don't know where it ends, but we know where it starts. If we're
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reading delta trace, we can fill in the start address later on.
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Otherwise we will prune it. */
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block.begin = 0;
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VEC_safe_push (btrace_block_s, btrace, &block);
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return btrace;
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}
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/* Check whether the kernel supports BTS. */
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static int
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kernel_supports_bts (void)
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{
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struct perf_event_attr attr;
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pid_t child, pid;
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int status, file;
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errno = 0;
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child = fork ();
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switch (child)
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{
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case -1:
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warning (_("test bts: cannot fork: %s."), safe_strerror (errno));
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return 0;
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case 0:
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status = ptrace (PTRACE_TRACEME, 0, NULL, NULL);
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if (status != 0)
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{
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warning (_("test bts: cannot PTRACE_TRACEME: %s."),
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safe_strerror (errno));
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_exit (1);
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}
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status = raise (SIGTRAP);
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if (status != 0)
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{
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warning (_("test bts: cannot raise SIGTRAP: %s."),
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safe_strerror (errno));
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_exit (1);
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}
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_exit (1);
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default:
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pid = waitpid (child, &status, 0);
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if (pid != child)
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{
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warning (_("test bts: bad pid %ld, error: %s."),
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(long) pid, safe_strerror (errno));
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return 0;
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}
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if (!WIFSTOPPED (status))
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{
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warning (_("test bts: expected stop. status: %d."),
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status);
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return 0;
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}
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memset (&attr, 0, sizeof (attr));
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attr.type = PERF_TYPE_HARDWARE;
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attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS;
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attr.sample_period = 1;
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attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR;
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attr.exclude_kernel = 1;
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attr.exclude_hv = 1;
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attr.exclude_idle = 1;
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file = syscall (SYS_perf_event_open, &attr, child, -1, -1, 0);
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if (file >= 0)
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close (file);
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kill (child, SIGKILL);
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ptrace (PTRACE_KILL, child, NULL, NULL);
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pid = waitpid (child, &status, 0);
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if (pid != child)
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{
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warning (_("test bts: bad pid %ld, error: %s."),
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(long) pid, safe_strerror (errno));
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if (!WIFSIGNALED (status))
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warning (_("test bts: expected killed. status: %d."),
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status);
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}
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return (file >= 0);
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}
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}
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/* Check whether the kernel supports Intel Processor Trace. */
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static int
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kernel_supports_pt (void)
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{
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struct perf_event_attr attr;
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pid_t child, pid;
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int status, file, type;
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errno = 0;
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child = fork ();
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switch (child)
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{
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case -1:
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warning (_("test pt: cannot fork: %s."), safe_strerror (errno));
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return 0;
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case 0:
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status = ptrace (PTRACE_TRACEME, 0, NULL, NULL);
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if (status != 0)
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{
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warning (_("test pt: cannot PTRACE_TRACEME: %s."),
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safe_strerror (errno));
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_exit (1);
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}
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status = raise (SIGTRAP);
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if (status != 0)
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{
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warning (_("test pt: cannot raise SIGTRAP: %s."),
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safe_strerror (errno));
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_exit (1);
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}
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_exit (1);
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default:
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pid = waitpid (child, &status, 0);
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if (pid != child)
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{
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warning (_("test pt: bad pid %ld, error: %s."),
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(long) pid, safe_strerror (errno));
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return 0;
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}
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if (!WIFSTOPPED (status))
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{
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warning (_("test pt: expected stop. status: %d."),
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status);
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return 0;
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}
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status = perf_event_pt_event_type (&type);
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if (status != 0)
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file = -1;
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else
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{
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memset (&attr, 0, sizeof (attr));
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attr.size = sizeof (attr);
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attr.type = type;
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attr.exclude_kernel = 1;
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attr.exclude_hv = 1;
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attr.exclude_idle = 1;
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file = syscall (SYS_perf_event_open, &attr, child, -1, -1, 0);
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if (file >= 0)
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close (file);
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}
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kill (child, SIGKILL);
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ptrace (PTRACE_KILL, child, NULL, NULL);
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pid = waitpid (child, &status, 0);
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if (pid != child)
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{
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warning (_("test pt: bad pid %ld, error: %s."),
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(long) pid, safe_strerror (errno));
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if (!WIFSIGNALED (status))
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warning (_("test pt: expected killed. status: %d."),
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status);
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}
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return (file >= 0);
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}
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}
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/* Check whether an Intel cpu supports BTS. */
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static int
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intel_supports_bts (const struct btrace_cpu *cpu)
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{
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switch (cpu->family)
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{
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case 0x6:
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switch (cpu->model)
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{
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case 0x1a: /* Nehalem */
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case 0x1f:
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case 0x1e:
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case 0x2e:
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case 0x25: /* Westmere */
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case 0x2c:
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case 0x2f:
|
|
case 0x2a: /* Sandy Bridge */
|
|
case 0x2d:
|
|
case 0x3a: /* Ivy Bridge */
|
|
|
|
/* AAJ122: LBR, BTM, or BTS records may have incorrect branch
|
|
"from" information afer an EIST transition, T-states, C1E, or
|
|
Adaptive Thermal Throttling. */
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
/* Check whether the cpu supports BTS. */
|
|
|
|
static int
|
|
cpu_supports_bts (void)
|
|
{
|
|
struct btrace_cpu cpu;
|
|
|
|
cpu = btrace_this_cpu ();
|
|
switch (cpu.vendor)
|
|
{
|
|
default:
|
|
/* Don't know about others. Let's assume they do. */
|
|
return 1;
|
|
|
|
case CV_INTEL:
|
|
return intel_supports_bts (&cpu);
|
|
}
|
|
}
|
|
|
|
/* Check whether the linux target supports BTS. */
|
|
|
|
static int
|
|
linux_supports_bts (void)
|
|
{
|
|
static int cached;
|
|
|
|
if (cached == 0)
|
|
{
|
|
if (!kernel_supports_bts ())
|
|
cached = -1;
|
|
else if (!cpu_supports_bts ())
|
|
cached = -1;
|
|
else
|
|
cached = 1;
|
|
}
|
|
|
|
return cached > 0;
|
|
}
|
|
|
|
/* Check whether the linux target supports Intel Processor Trace. */
|
|
|
|
static int
|
|
linux_supports_pt (void)
|
|
{
|
|
static int cached;
|
|
|
|
if (cached == 0)
|
|
{
|
|
if (!kernel_supports_pt ())
|
|
cached = -1;
|
|
else
|
|
cached = 1;
|
|
}
|
|
|
|
return cached > 0;
|
|
}
|
|
|
|
/* See linux-btrace.h. */
|
|
|
|
int
|
|
linux_supports_btrace (struct target_ops *ops, enum btrace_format format)
|
|
{
|
|
switch (format)
|
|
{
|
|
case BTRACE_FORMAT_NONE:
|
|
return 0;
|
|
|
|
case BTRACE_FORMAT_BTS:
|
|
return linux_supports_bts ();
|
|
|
|
case BTRACE_FORMAT_PT:
|
|
return linux_supports_pt ();
|
|
}
|
|
|
|
internal_error (__FILE__, __LINE__, _("Unknown branch trace format"));
|
|
}
|
|
|
|
/* Enable branch tracing in BTS format. */
|
|
|
|
static struct btrace_target_info *
|
|
linux_enable_bts (ptid_t ptid, const struct btrace_config_bts *conf)
|
|
{
|
|
struct perf_event_mmap_page *header;
|
|
struct btrace_target_info *tinfo;
|
|
struct btrace_tinfo_bts *bts;
|
|
size_t size, pages;
|
|
__u64 data_offset;
|
|
int pid, pg;
|
|
|
|
tinfo = XCNEW (struct btrace_target_info);
|
|
tinfo->ptid = ptid;
|
|
|
|
tinfo->conf.format = BTRACE_FORMAT_BTS;
|
|
bts = &tinfo->variant.bts;
|
|
|
|
bts->attr.size = sizeof (bts->attr);
|
|
bts->attr.type = PERF_TYPE_HARDWARE;
|
|
bts->attr.config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS;
|
|
bts->attr.sample_period = 1;
|
|
|
|
/* We sample from and to address. */
|
|
bts->attr.sample_type = PERF_SAMPLE_IP | PERF_SAMPLE_ADDR;
|
|
|
|
bts->attr.exclude_kernel = 1;
|
|
bts->attr.exclude_hv = 1;
|
|
bts->attr.exclude_idle = 1;
|
|
|
|
pid = ptid_get_lwp (ptid);
|
|
if (pid == 0)
|
|
pid = ptid_get_pid (ptid);
|
|
|
|
errno = 0;
|
|
bts->file = syscall (SYS_perf_event_open, &bts->attr, pid, -1, -1, 0);
|
|
if (bts->file < 0)
|
|
goto err_out;
|
|
|
|
/* Convert the requested size in bytes to pages (rounding up). */
|
|
pages = ((size_t) conf->size / PAGE_SIZE
|
|
+ ((conf->size % PAGE_SIZE) == 0 ? 0 : 1));
|
|
/* We need at least one page. */
|
|
if (pages == 0)
|
|
pages = 1;
|
|
|
|
/* The buffer size can be requested in powers of two pages. Adjust PAGES
|
|
to the next power of two. */
|
|
for (pg = 0; pages != ((size_t) 1 << pg); ++pg)
|
|
if ((pages & ((size_t) 1 << pg)) != 0)
|
|
pages += ((size_t) 1 << pg);
|
|
|
|
/* We try to allocate the requested size.
|
|
If that fails, try to get as much as we can. */
|
|
for (; pages > 0; pages >>= 1)
|
|
{
|
|
size_t length;
|
|
__u64 data_size;
|
|
|
|
data_size = (__u64) pages * PAGE_SIZE;
|
|
|
|
/* Don't ask for more than we can represent in the configuration. */
|
|
if ((__u64) UINT_MAX < data_size)
|
|
continue;
|
|
|
|
size = (size_t) data_size;
|
|
length = size + PAGE_SIZE;
|
|
|
|
/* Check for overflows. */
|
|
if ((__u64) length != data_size + PAGE_SIZE)
|
|
continue;
|
|
|
|
/* The number of pages we request needs to be a power of two. */
|
|
header = ((struct perf_event_mmap_page *)
|
|
mmap (NULL, length, PROT_READ, MAP_SHARED, bts->file, 0));
|
|
if (header != MAP_FAILED)
|
|
break;
|
|
}
|
|
|
|
if (pages == 0)
|
|
goto err_file;
|
|
|
|
data_offset = PAGE_SIZE;
|
|
|
|
#if defined (PERF_ATTR_SIZE_VER5)
|
|
if (offsetof (struct perf_event_mmap_page, data_size) <= header->size)
|
|
{
|
|
__u64 data_size;
|
|
|
|
data_offset = header->data_offset;
|
|
data_size = header->data_size;
|
|
|
|
size = (unsigned int) data_size;
|
|
|
|
/* Check for overflows. */
|
|
if ((__u64) size != data_size)
|
|
{
|
|
munmap ((void *) header, size + PAGE_SIZE);
|
|
goto err_file;
|
|
}
|
|
}
|
|
#endif /* defined (PERF_ATTR_SIZE_VER5) */
|
|
|
|
bts->header = header;
|
|
bts->bts.mem = ((const uint8_t *) header) + data_offset;
|
|
bts->bts.size = size;
|
|
bts->bts.data_head = &header->data_head;
|
|
bts->bts.last_head = 0ull;
|
|
|
|
tinfo->conf.bts.size = (unsigned int) size;
|
|
return tinfo;
|
|
|
|
err_file:
|
|
/* We were not able to allocate any buffer. */
|
|
close (bts->file);
|
|
|
|
err_out:
|
|
xfree (tinfo);
|
|
return NULL;
|
|
}
|
|
|
|
#if defined (PERF_ATTR_SIZE_VER5)
|
|
|
|
/* Enable branch tracing in Intel Processor Trace format. */
|
|
|
|
static struct btrace_target_info *
|
|
linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf)
|
|
{
|
|
struct perf_event_mmap_page *header;
|
|
struct btrace_target_info *tinfo;
|
|
struct btrace_tinfo_pt *pt;
|
|
size_t pages, size;
|
|
int pid, pg, errcode, type;
|
|
|
|
if (conf->size == 0)
|
|
return NULL;
|
|
|
|
errcode = perf_event_pt_event_type (&type);
|
|
if (errcode != 0)
|
|
return NULL;
|
|
|
|
pid = ptid_get_lwp (ptid);
|
|
if (pid == 0)
|
|
pid = ptid_get_pid (ptid);
|
|
|
|
tinfo = XCNEW (struct btrace_target_info);
|
|
tinfo->ptid = ptid;
|
|
|
|
tinfo->conf.format = BTRACE_FORMAT_PT;
|
|
pt = &tinfo->variant.pt;
|
|
|
|
pt->attr.size = sizeof (pt->attr);
|
|
pt->attr.type = type;
|
|
|
|
pt->attr.exclude_kernel = 1;
|
|
pt->attr.exclude_hv = 1;
|
|
pt->attr.exclude_idle = 1;
|
|
|
|
errno = 0;
|
|
pt->file = syscall (SYS_perf_event_open, &pt->attr, pid, -1, -1, 0);
|
|
if (pt->file < 0)
|
|
goto err;
|
|
|
|
/* Allocate the configuration page. */
|
|
header = ((struct perf_event_mmap_page *)
|
|
mmap (NULL, PAGE_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED,
|
|
pt->file, 0));
|
|
if (header == MAP_FAILED)
|
|
goto err_file;
|
|
|
|
header->aux_offset = header->data_offset + header->data_size;
|
|
|
|
/* Convert the requested size in bytes to pages (rounding up). */
|
|
pages = ((size_t) conf->size / PAGE_SIZE
|
|
+ ((conf->size % PAGE_SIZE) == 0 ? 0 : 1));
|
|
/* We need at least one page. */
|
|
if (pages == 0)
|
|
pages = 1;
|
|
|
|
/* The buffer size can be requested in powers of two pages. Adjust PAGES
|
|
to the next power of two. */
|
|
for (pg = 0; pages != ((size_t) 1 << pg); ++pg)
|
|
if ((pages & ((size_t) 1 << pg)) != 0)
|
|
pages += ((size_t) 1 << pg);
|
|
|
|
/* We try to allocate the requested size.
|
|
If that fails, try to get as much as we can. */
|
|
for (; pages > 0; pages >>= 1)
|
|
{
|
|
size_t length;
|
|
__u64 data_size;
|
|
|
|
data_size = (__u64) pages * PAGE_SIZE;
|
|
|
|
/* Don't ask for more than we can represent in the configuration. */
|
|
if ((__u64) UINT_MAX < data_size)
|
|
continue;
|
|
|
|
size = (size_t) data_size;
|
|
|
|
/* Check for overflows. */
|
|
if ((__u64) size != data_size)
|
|
continue;
|
|
|
|
header->aux_size = data_size;
|
|
length = size;
|
|
|
|
pt->pt.mem = ((const uint8_t *)
|
|
mmap (NULL, length, PROT_READ, MAP_SHARED, pt->file,
|
|
header->aux_offset));
|
|
if (pt->pt.mem != MAP_FAILED)
|
|
break;
|
|
}
|
|
|
|
if (pages == 0)
|
|
goto err_conf;
|
|
|
|
pt->header = header;
|
|
pt->pt.size = size;
|
|
pt->pt.data_head = &header->aux_head;
|
|
|
|
tinfo->conf.pt.size = (unsigned int) size;
|
|
return tinfo;
|
|
|
|
err_conf:
|
|
munmap((void *) header, PAGE_SIZE);
|
|
|
|
err_file:
|
|
close (pt->file);
|
|
|
|
err:
|
|
xfree (tinfo);
|
|
return NULL;
|
|
}
|
|
|
|
#else /* !defined (PERF_ATTR_SIZE_VER5) */
|
|
|
|
static struct btrace_target_info *
|
|
linux_enable_pt (ptid_t ptid, const struct btrace_config_pt *conf)
|
|
{
|
|
errno = EOPNOTSUPP;
|
|
return NULL;
|
|
}
|
|
|
|
#endif /* !defined (PERF_ATTR_SIZE_VER5) */
|
|
|
|
/* See linux-btrace.h. */
|
|
|
|
struct btrace_target_info *
|
|
linux_enable_btrace (ptid_t ptid, const struct btrace_config *conf)
|
|
{
|
|
struct btrace_target_info *tinfo;
|
|
|
|
tinfo = NULL;
|
|
switch (conf->format)
|
|
{
|
|
case BTRACE_FORMAT_NONE:
|
|
break;
|
|
|
|
case BTRACE_FORMAT_BTS:
|
|
tinfo = linux_enable_bts (ptid, &conf->bts);
|
|
break;
|
|
|
|
case BTRACE_FORMAT_PT:
|
|
tinfo = linux_enable_pt (ptid, &conf->pt);
|
|
break;
|
|
}
|
|
|
|
return tinfo;
|
|
}
|
|
|
|
/* Disable BTS tracing. */
|
|
|
|
static enum btrace_error
|
|
linux_disable_bts (struct btrace_tinfo_bts *tinfo)
|
|
{
|
|
munmap((void *) tinfo->header, tinfo->bts.size + PAGE_SIZE);
|
|
close (tinfo->file);
|
|
|
|
return BTRACE_ERR_NONE;
|
|
}
|
|
|
|
/* Disable Intel Processor Trace tracing. */
|
|
|
|
static enum btrace_error
|
|
linux_disable_pt (struct btrace_tinfo_pt *tinfo)
|
|
{
|
|
munmap((void *) tinfo->pt.mem, tinfo->pt.size);
|
|
munmap((void *) tinfo->header, PAGE_SIZE);
|
|
close (tinfo->file);
|
|
|
|
return BTRACE_ERR_NONE;
|
|
}
|
|
|
|
/* See linux-btrace.h. */
|
|
|
|
enum btrace_error
|
|
linux_disable_btrace (struct btrace_target_info *tinfo)
|
|
{
|
|
enum btrace_error errcode;
|
|
|
|
errcode = BTRACE_ERR_NOT_SUPPORTED;
|
|
switch (tinfo->conf.format)
|
|
{
|
|
case BTRACE_FORMAT_NONE:
|
|
break;
|
|
|
|
case BTRACE_FORMAT_BTS:
|
|
errcode = linux_disable_bts (&tinfo->variant.bts);
|
|
break;
|
|
|
|
case BTRACE_FORMAT_PT:
|
|
errcode = linux_disable_pt (&tinfo->variant.pt);
|
|
break;
|
|
}
|
|
|
|
if (errcode == BTRACE_ERR_NONE)
|
|
xfree (tinfo);
|
|
|
|
return errcode;
|
|
}
|
|
|
|
/* Read branch trace data in BTS format for the thread given by TINFO into
|
|
BTRACE using the TYPE reading method. */
|
|
|
|
static enum btrace_error
|
|
linux_read_bts (struct btrace_data_bts *btrace,
|
|
struct btrace_target_info *tinfo,
|
|
enum btrace_read_type type)
|
|
{
|
|
struct perf_event_buffer *pevent;
|
|
const uint8_t *begin, *end, *start;
|
|
size_t buffer_size, size;
|
|
__u64 data_head, data_tail;
|
|
unsigned int retries = 5;
|
|
|
|
pevent = &tinfo->variant.bts.bts;
|
|
|
|
/* For delta reads, we return at least the partial last block containing
|
|
the current PC. */
|
|
if (type == BTRACE_READ_NEW && !perf_event_new_data (pevent))
|
|
return BTRACE_ERR_NONE;
|
|
|
|
buffer_size = pevent->size;
|
|
data_tail = pevent->last_head;
|
|
|
|
/* We may need to retry reading the trace. See below. */
|
|
while (retries--)
|
|
{
|
|
data_head = *pevent->data_head;
|
|
|
|
/* Delete any leftover trace from the previous iteration. */
|
|
VEC_free (btrace_block_s, btrace->blocks);
|
|
|
|
if (type == BTRACE_READ_DELTA)
|
|
{
|
|
__u64 data_size;
|
|
|
|
/* Determine the number of bytes to read and check for buffer
|
|
overflows. */
|
|
|
|
/* Check for data head overflows. We might be able to recover from
|
|
those but they are very unlikely and it's not really worth the
|
|
effort, I think. */
|
|
if (data_head < data_tail)
|
|
return BTRACE_ERR_OVERFLOW;
|
|
|
|
/* If the buffer is smaller than the trace delta, we overflowed. */
|
|
data_size = data_head - data_tail;
|
|
if (buffer_size < data_size)
|
|
return BTRACE_ERR_OVERFLOW;
|
|
|
|
/* DATA_SIZE <= BUFFER_SIZE and therefore fits into a size_t. */
|
|
size = (size_t) data_size;
|
|
}
|
|
else
|
|
{
|
|
/* Read the entire buffer. */
|
|
size = buffer_size;
|
|
|
|
/* Adjust the size if the buffer has not overflowed, yet. */
|
|
if (data_head < size)
|
|
size = (size_t) data_head;
|
|
}
|
|
|
|
/* Data_head keeps growing; the buffer itself is circular. */
|
|
begin = pevent->mem;
|
|
start = begin + data_head % buffer_size;
|
|
|
|
if (data_head <= buffer_size)
|
|
end = start;
|
|
else
|
|
end = begin + pevent->size;
|
|
|
|
btrace->blocks = perf_event_read_bts (tinfo, begin, end, start, size);
|
|
|
|
/* The stopping thread notifies its ptracer before it is scheduled out.
|
|
On multi-core systems, the debugger might therefore run while the
|
|
kernel might be writing the last branch trace records.
|
|
|
|
Let's check whether the data head moved while we read the trace. */
|
|
if (data_head == *pevent->data_head)
|
|
break;
|
|
}
|
|
|
|
pevent->last_head = data_head;
|
|
|
|
/* Prune the incomplete last block (i.e. the first one of inferior execution)
|
|
if we're not doing a delta read. There is no way of filling in its zeroed
|
|
BEGIN element. */
|
|
if (!VEC_empty (btrace_block_s, btrace->blocks)
|
|
&& type != BTRACE_READ_DELTA)
|
|
VEC_pop (btrace_block_s, btrace->blocks);
|
|
|
|
return BTRACE_ERR_NONE;
|
|
}
|
|
|
|
/* Fill in the Intel Processor Trace configuration information. */
|
|
|
|
static void
|
|
linux_fill_btrace_pt_config (struct btrace_data_pt_config *conf)
|
|
{
|
|
conf->cpu = btrace_this_cpu ();
|
|
}
|
|
|
|
/* Read branch trace data in Intel Processor Trace format for the thread
|
|
given by TINFO into BTRACE using the TYPE reading method. */
|
|
|
|
static enum btrace_error
|
|
linux_read_pt (struct btrace_data_pt *btrace,
|
|
struct btrace_target_info *tinfo,
|
|
enum btrace_read_type type)
|
|
{
|
|
struct perf_event_buffer *pt;
|
|
|
|
pt = &tinfo->variant.pt.pt;
|
|
|
|
linux_fill_btrace_pt_config (&btrace->config);
|
|
|
|
switch (type)
|
|
{
|
|
case BTRACE_READ_DELTA:
|
|
/* We don't support delta reads. The data head (i.e. aux_head) wraps
|
|
around to stay inside the aux buffer. */
|
|
return BTRACE_ERR_NOT_SUPPORTED;
|
|
|
|
case BTRACE_READ_NEW:
|
|
if (!perf_event_new_data (pt))
|
|
return BTRACE_ERR_NONE;
|
|
|
|
/* Fall through. */
|
|
case BTRACE_READ_ALL:
|
|
perf_event_read_all (pt, &btrace->data, &btrace->size);
|
|
return BTRACE_ERR_NONE;
|
|
}
|
|
|
|
internal_error (__FILE__, __LINE__, _("Unkown btrace read type."));
|
|
}
|
|
|
|
/* See linux-btrace.h. */
|
|
|
|
enum btrace_error
|
|
linux_read_btrace (struct btrace_data *btrace,
|
|
struct btrace_target_info *tinfo,
|
|
enum btrace_read_type type)
|
|
{
|
|
switch (tinfo->conf.format)
|
|
{
|
|
case BTRACE_FORMAT_NONE:
|
|
return BTRACE_ERR_NOT_SUPPORTED;
|
|
|
|
case BTRACE_FORMAT_BTS:
|
|
/* We read btrace in BTS format. */
|
|
btrace->format = BTRACE_FORMAT_BTS;
|
|
btrace->variant.bts.blocks = NULL;
|
|
|
|
return linux_read_bts (&btrace->variant.bts, tinfo, type);
|
|
|
|
case BTRACE_FORMAT_PT:
|
|
/* We read btrace in Intel Processor Trace format. */
|
|
btrace->format = BTRACE_FORMAT_PT;
|
|
btrace->variant.pt.data = NULL;
|
|
btrace->variant.pt.size = 0;
|
|
|
|
return linux_read_pt (&btrace->variant.pt, tinfo, type);
|
|
}
|
|
|
|
internal_error (__FILE__, __LINE__, _("Unkown branch trace format."));
|
|
}
|
|
|
|
/* See linux-btrace.h. */
|
|
|
|
const struct btrace_config *
|
|
linux_btrace_conf (const struct btrace_target_info *tinfo)
|
|
{
|
|
return &tinfo->conf;
|
|
}
|
|
|
|
#else /* !HAVE_LINUX_PERF_EVENT_H */
|
|
|
|
/* See linux-btrace.h. */
|
|
|
|
int
|
|
linux_supports_btrace (struct target_ops *ops, enum btrace_format format)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
/* See linux-btrace.h. */
|
|
|
|
struct btrace_target_info *
|
|
linux_enable_btrace (ptid_t ptid, const struct btrace_config *conf)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
/* See linux-btrace.h. */
|
|
|
|
enum btrace_error
|
|
linux_disable_btrace (struct btrace_target_info *tinfo)
|
|
{
|
|
return BTRACE_ERR_NOT_SUPPORTED;
|
|
}
|
|
|
|
/* See linux-btrace.h. */
|
|
|
|
enum btrace_error
|
|
linux_read_btrace (struct btrace_data *btrace,
|
|
struct btrace_target_info *tinfo,
|
|
enum btrace_read_type type)
|
|
{
|
|
return BTRACE_ERR_NOT_SUPPORTED;
|
|
}
|
|
|
|
/* See linux-btrace.h. */
|
|
|
|
const struct btrace_config *
|
|
linux_btrace_conf (const struct btrace_target_info *tinfo)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
#endif /* !HAVE_LINUX_PERF_EVENT_H */
|