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hurd: Add enough auxv support for AT_ENTRY for PIE binaries

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Add PIE support for hurd, by faking an AT_ENTRY auxv entry.  That value
is expected to be read by svr4_exec_displacement, which will propagate
the executable displacement.

gdb/ChangeLog:

	* gdb/gnu-nat.c: Include <elf.h> and <link.h>.
	(gnu_xfer_auxv): New function.
	(gnu_xfer_partial): Call gnu_xfer_auxv when `object' is
	TARGET_OBJECT_AUXV.
This commit is contained in:
Samuel Thibault 2018-01-08 10:30:16 -05:00 committed by Simon Marchi
parent 704a705d7a
commit 9c4ac400f0
2 changed files with 65 additions and 0 deletions
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7
gdb/ChangeLog
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@ -1,3 +1,10 @@
2018-01-08 Samuel Thibault <samuel.thibault@ens-lyon.org>
* gdb/gnu-nat.c: Include <elf.h> and <link.h>.
(gnu_xfer_auxv): New function.
(gnu_xfer_partial): Call gnu_xfer_auxv when `object' is
TARGET_OBJECT_AUXV.
2018-01-08 Yao Qi <yao.qi@linaro.org>
Simon Marchi <simon.marchi@ericsson.com>

58
gdb/gnu-nat.c
View File

@ -52,6 +52,8 @@ extern "C"
#include <setjmp.h>
#include <signal.h>
#include <sys/ptrace.h>
#include <elf.h>
#include <link.h>
#include "inferior.h"
#include "symtab.h"
@ -2541,6 +2543,60 @@ gnu_xfer_memory (gdb_byte *readbuf, const gdb_byte *writebuf,
}
}
/* GNU does not have auxv, but we can at least fake the AT_ENTRY entry for PIE
binaries. */
static enum target_xfer_status
gnu_xfer_auxv (gdb_byte *readbuf, const gdb_byte *writebuf,
CORE_ADDR memaddr, ULONGEST len, ULONGEST *xfered_len)
{
task_t task = (gnu_current_inf
? (gnu_current_inf->task
? gnu_current_inf->task->port : 0)
: 0);
process_t proc;
int res;
kern_return_t err;
vm_address_t entry;
ElfW(auxv_t) auxv[2];
if (task == MACH_PORT_NULL)
return TARGET_XFER_E_IO;
if (writebuf != NULL)
return TARGET_XFER_E_IO;
if (memaddr == sizeof (auxv))
return TARGET_XFER_EOF;
if (memaddr > sizeof (auxv))
return TARGET_XFER_E_IO;
err = proc_task2proc (proc_server, task, &proc);
if (err != 0)
return TARGET_XFER_E_IO;
/* Get entry from proc server. */
err = proc_get_entry (proc, &entry);
if (err != 0)
return TARGET_XFER_E_IO;
/* Fake auxv entry. */
auxv[0].a_type = AT_ENTRY;
auxv[0].a_un.a_val = entry;
auxv[1].a_type = AT_NULL;
auxv[1].a_un.a_val = 0;
inf_debug (gnu_current_inf, "reading auxv %s[%s] --> %s",
paddress (target_gdbarch (), memaddr), pulongest (len),
host_address_to_string (readbuf));
if (memaddr + len > sizeof (auxv))
len = sizeof (auxv) - memaddr;
memcpy (readbuf, (gdb_byte *) &auxv + memaddr, len);
*xfered_len = len;
return TARGET_XFER_OK;
}
/* Target to_xfer_partial implementation. */
static enum target_xfer_status
@ -2553,6 +2609,8 @@ gnu_xfer_partial (struct target_ops *ops, enum target_object object,
{
case TARGET_OBJECT_MEMORY:
return gnu_xfer_memory (readbuf, writebuf, offset, len, xfered_len);
case TARGET_OBJECT_AUXV:
return gnu_xfer_auxv (readbuf, writebuf, offset, len, xfered_len);
default:
return TARGET_XFER_E_IO;
}