2000-03-04 Mark Kettenis <kettenis@gnu.org>
Fix support for Linux/i386 signal trampolines. The old approach
didn't work for Linux 2.2 and beyond, and didn't work with recent
versions of the GNU C library.
* i386-tdep.c (LINUX_RT_SIGTRAMP_INSN0, LINUX_RT_SIGTRAMP_OFFSET0,
LINUX_RT_SIGTRAMP_INSN1, LINUX_RT_SIGTRAMP_OFFSET1): New defines.
(linux_rt_sigtramp_code): New variable.
(LINUX_RT_SIGTRAMP_LEN): New define.
(i386_linux_rt_sigtramp_start): New function. Detect start of
signal trampolines for RT signals.
(i386_linux_sigtramp): Removed.
(i386_linux_in_sigtramp): New function.
(i386_linux_sigcontext_addr): New function. Recognize the names
of the signal tranmpolines used by recent versions of the GNU C
library, and add support for RT signals.
(LINUX_SIGCONTEXT_PC_OFFSET, LINUX_SIGCONTEXT_SP_OFFSET): New
defines. Moved here from config/i386/tm-linux.h.
(i386_linux_sigtramp_saved_pc, i386_linux_sigtramp_saved_sp):
Reimplement in terms of i386_linux_sigcontext_addr.
* config/i386/tm-linux.h (LINUX_SIGCONTEXT_SIZE): Removed.
(LINUX_SIGCONTEXT_PC_OFFSET, LINUX_SIGCONTEXT_SP_OFFSET):
Moved to i386-tdep.c.
(IN_SIGTRAMP): Redefine to call i386_linux_in_sigtramp.
This commit is contained in:
Mark Kettenis
parent
8ae7f924f3
commit
45a816d93e
|
|
@ -1,3 +1,28 @@
|
|||
2000-03-04 Mark Kettenis <kettenis@gnu.org>
|
||||
|
||||
Fix support for Linux/i386 signal trampolines. The old approach
|
||||
didn't work for Linux 2.2 and beyond, and didn't work with recent
|
||||
versions of the GNU C library.
|
||||
* i386-tdep.c (LINUX_RT_SIGTRAMP_INSN0, LINUX_RT_SIGTRAMP_OFFSET0,
|
||||
LINUX_RT_SIGTRAMP_INSN1, LINUX_RT_SIGTRAMP_OFFSET1): New defines.
|
||||
(linux_rt_sigtramp_code): New variable.
|
||||
(LINUX_RT_SIGTRAMP_LEN): New define.
|
||||
(i386_linux_rt_sigtramp_start): New function. Detect start of
|
||||
signal trampolines for RT signals.
|
||||
(i386_linux_sigtramp): Removed.
|
||||
(i386_linux_in_sigtramp): New function.
|
||||
(i386_linux_sigcontext_addr): New function. Recognize the names
|
||||
of the signal tranmpolines used by recent versions of the GNU C
|
||||
library, and add support for RT signals.
|
||||
(LINUX_SIGCONTEXT_PC_OFFSET, LINUX_SIGCONTEXT_SP_OFFSET): New
|
||||
defines. Moved here from config/i386/tm-linux.h.
|
||||
(i386_linux_sigtramp_saved_pc, i386_linux_sigtramp_saved_sp):
|
||||
Reimplement in terms of i386_linux_sigcontext_addr.
|
||||
* config/i386/tm-linux.h (LINUX_SIGCONTEXT_SIZE): Removed.
|
||||
(LINUX_SIGCONTEXT_PC_OFFSET, LINUX_SIGCONTEXT_SP_OFFSET):
|
||||
Moved to i386-tdep.c.
|
||||
(IN_SIGTRAMP): Redefine to call i386_linux_in_sigtramp.
|
||||
|
||||
Sat Mar 4 19:38:11 2000 Andrew Cagney <cagney@b1.cygnus.com>
|
||||
|
||||
By: Sat Mar 4 04:08:58 2000 Alexandre Oliva <oliva@lsd.ic.unicamp.br>
|
||||
|
|
|
|||
|
|
@ -30,15 +30,6 @@
|
|||
#include "i386/tm-i386.h"
|
||||
#include "tm-linux.h"
|
||||
|
||||
/* Size of sigcontext, from <asm/sigcontext.h>. */
|
||||
#define LINUX_SIGCONTEXT_SIZE (88)
|
||||
|
||||
/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>. */
|
||||
#define LINUX_SIGCONTEXT_PC_OFFSET (56)
|
||||
|
||||
/* Offset to saved SP in sigcontext, from <asm/sigcontext.h>. */
|
||||
#define LINUX_SIGCONTEXT_SP_OFFSET (28)
|
||||
|
||||
#define LOW_RETURN_REGNUM 0 /* holds low four bytes of result */
|
||||
#define HIGH_RETURN_REGNUM 2 /* holds high four bytes of result */
|
||||
|
||||
|
|
@ -108,15 +99,14 @@ extern int i387_store_floating (PTR addr, int len, long double val);
|
|||
order to support backtracing through calls to signal handlers. */
|
||||
|
||||
#define I386_LINUX_SIGTRAMP
|
||||
#define IN_SIGTRAMP(pc, name) ((name) == NULL && i386_linux_sigtramp (pc))
|
||||
|
||||
extern int i386_linux_sigtramp PARAMS ((CORE_ADDR));
|
||||
#define IN_SIGTRAMP(pc, name) i386_linux_in_sigtramp (pc, name)
|
||||
extern int i386_linux_in_sigtramp (CORE_ADDR, char *);
|
||||
|
||||
/* We need our own version of sigtramp_saved_pc to get the saved PC in
|
||||
a sigtramp routine. */
|
||||
|
||||
#define sigtramp_saved_pc i386_linux_sigtramp_saved_pc
|
||||
extern CORE_ADDR i386_linux_sigtramp_saved_pc PARAMS ((struct frame_info *));
|
||||
extern CORE_ADDR i386_linux_sigtramp_saved_pc (struct frame_info *);
|
||||
|
||||
/* Signal trampolines don't have a meaningful frame. As in tm-i386.h,
|
||||
the frame pointer value we use is actually the frame pointer of the
|
||||
|
|
@ -162,7 +152,7 @@ extern CORE_ADDR i386_linux_sigtramp_saved_pc PARAMS ((struct frame_info *));
|
|||
? read_memory_integer (i386_linux_sigtramp_saved_sp ((FRAME)->next), 4) \
|
||||
: read_memory_integer ((FRAME)->frame + 4, 4)))
|
||||
|
||||
extern CORE_ADDR i386_linux_sigtramp_saved_sp PARAMS ((struct frame_info *));
|
||||
extern CORE_ADDR i386_linux_sigtramp_saved_sp (struct frame_info *);
|
||||
|
||||
/* When we call a function in a shared library, and the PLT sends us
|
||||
into the dynamic linker to find the function's real address, we
|
||||
|
|
|
|||
179
gdb/i386-tdep.c
179
gdb/i386-tdep.c
|
|
@ -781,11 +781,19 @@ i386v4_sigtramp_saved_pc (frame)
|
|||
|
||||
#ifdef I386_LINUX_SIGTRAMP
|
||||
|
||||
/* When the i386 Linux kernel calls a signal handler, the return
|
||||
address points to a bit of code on the stack. This function
|
||||
returns whether the PC appears to be within this bit of code.
|
||||
/* Linux has two flavors of signals. Normal signal handlers, and
|
||||
"realtime" (RT) signals. The RT signals can provide additional
|
||||
information to the signal handler if the SA_SIGINFO flag is set
|
||||
when establishing a signal handler using `sigaction'. It is not
|
||||
unlikely that future versions of Linux will support SA_SIGINFO for
|
||||
normal signals too. */
|
||||
|
||||
The instruction sequence is
|
||||
/* When the i386 Linux kernel calls a signal handler and the
|
||||
SA_RESTORER flag isn't set, the return address points to a bit of
|
||||
code on the stack. This function returns whether the PC appears to
|
||||
be within this bit of code.
|
||||
|
||||
The instruction sequence for normal signals is
|
||||
pop %eax
|
||||
mov $0x77,%eax
|
||||
int $0x80
|
||||
|
|
@ -799,7 +807,15 @@ i386v4_sigtramp_saved_pc (frame)
|
|||
order to identify a signal trampoline, but there doesn't seem to be
|
||||
any other way. The IN_SIGTRAMP macro in tm-linux.h arranges to
|
||||
only call us if no function name could be identified, which should
|
||||
be the case since the code is on the stack. */
|
||||
be the case since the code is on the stack.
|
||||
|
||||
Detection of signal trampolines for handlers that set the
|
||||
SA_RESTORER flag is in general not possible. Unfortunately this is
|
||||
what the GNU C Library has been doing for quite some time now.
|
||||
However, as of version 2.1.2, the GNU C Library uses signal
|
||||
trampolines (named __restore and __restore_rt) that are identical
|
||||
to the ones used by the kernel. Therefore, these trampolines are
|
||||
supported too. */
|
||||
|
||||
#define LINUX_SIGTRAMP_INSN0 (0x58) /* pop %eax */
|
||||
#define LINUX_SIGTRAMP_OFFSET0 (0)
|
||||
|
|
@ -821,8 +837,7 @@ static const unsigned char linux_sigtramp_code[] =
|
|||
the routine. Otherwise, return 0. */
|
||||
|
||||
static CORE_ADDR
|
||||
i386_linux_sigtramp_start (pc)
|
||||
CORE_ADDR pc;
|
||||
i386_linux_sigtramp_start (CORE_ADDR pc)
|
||||
{
|
||||
unsigned char buf[LINUX_SIGTRAMP_LEN];
|
||||
|
||||
|
|
@ -864,51 +879,149 @@ i386_linux_sigtramp_start (pc)
|
|||
return pc;
|
||||
}
|
||||
|
||||
/* This function does the same for RT signals. Here the instruction
|
||||
sequence is
|
||||
mov $0xad,%eax
|
||||
int $0x80
|
||||
or 0xb8 0xad 0x00 0x00 0x00 0xcd 0x80.
|
||||
|
||||
The effect is to call the system call rt_sigreturn. */
|
||||
|
||||
#define LINUX_RT_SIGTRAMP_INSN0 (0xb8) /* mov $NNNN,%eax */
|
||||
#define LINUX_RT_SIGTRAMP_OFFSET0 (0)
|
||||
#define LINUX_RT_SIGTRAMP_INSN1 (0xcd) /* int */
|
||||
#define LINUX_RT_SIGTRAMP_OFFSET1 (5)
|
||||
|
||||
static const unsigned char linux_rt_sigtramp_code[] =
|
||||
{
|
||||
LINUX_RT_SIGTRAMP_INSN0, 0xad, 0x00, 0x00, 0x00, /* mov $0xad,%eax */
|
||||
LINUX_RT_SIGTRAMP_INSN1, 0x80 /* int $0x80 */
|
||||
};
|
||||
|
||||
#define LINUX_RT_SIGTRAMP_LEN (sizeof linux_rt_sigtramp_code)
|
||||
|
||||
/* If PC is in a RT sigtramp routine, return the address of the start
|
||||
of the routine. Otherwise, return 0. */
|
||||
|
||||
static CORE_ADDR
|
||||
i386_linux_rt_sigtramp_start (CORE_ADDR pc)
|
||||
{
|
||||
unsigned char buf[LINUX_RT_SIGTRAMP_LEN];
|
||||
|
||||
/* We only recognize a signal trampoline if PC is at the start of
|
||||
one of the two instructions. We optimize for finding the PC at
|
||||
the start, as will be the case when the trampoline is not the
|
||||
first frame on the stack. We assume that in the case where the
|
||||
PC is not at the start of the instruction sequence, there will be
|
||||
a few trailing readable bytes on the stack. */
|
||||
|
||||
if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
|
||||
return 0;
|
||||
|
||||
if (buf[0] != LINUX_RT_SIGTRAMP_INSN0)
|
||||
{
|
||||
if (buf[0] != LINUX_RT_SIGTRAMP_INSN1)
|
||||
return 0;
|
||||
|
||||
pc -= LINUX_RT_SIGTRAMP_OFFSET1;
|
||||
|
||||
if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
|
||||
return 0;
|
||||
}
|
||||
|
||||
if (memcmp (buf, linux_rt_sigtramp_code, LINUX_RT_SIGTRAMP_LEN) != 0)
|
||||
return 0;
|
||||
|
||||
return pc;
|
||||
}
|
||||
|
||||
/* Return whether PC is in a Linux sigtramp routine. */
|
||||
|
||||
int
|
||||
i386_linux_sigtramp (pc)
|
||||
CORE_ADDR pc;
|
||||
i386_linux_in_sigtramp (CORE_ADDR pc, char *name)
|
||||
{
|
||||
return i386_linux_sigtramp_start (pc) != 0;
|
||||
if (name)
|
||||
return STREQ ("__restore", name) || STREQ ("__restore_rt", name);
|
||||
|
||||
return (i386_linux_sigtramp_start (pc) != 0
|
||||
|| i386_linux_rt_sigtramp_start (pc) != 0);
|
||||
}
|
||||
|
||||
/* Assuming FRAME is for a Linux sigtramp routine, return the saved
|
||||
program counter. The Linux kernel will set up a sigcontext
|
||||
structure immediately before the sigtramp routine on the stack. */
|
||||
/* Assuming FRAME is for a Linux sigtramp routine, return the address
|
||||
of the associated sigcontext structure. */
|
||||
|
||||
CORE_ADDR
|
||||
i386_linux_sigtramp_saved_pc (frame)
|
||||
struct frame_info *frame;
|
||||
i386_linux_sigcontext_addr (struct frame_info *frame)
|
||||
{
|
||||
CORE_ADDR pc;
|
||||
|
||||
pc = i386_linux_sigtramp_start (frame->pc);
|
||||
if (pc == 0)
|
||||
error ("i386_linux_sigtramp_saved_pc called when no sigtramp");
|
||||
return read_memory_integer ((pc
|
||||
- LINUX_SIGCONTEXT_SIZE
|
||||
+ LINUX_SIGCONTEXT_PC_OFFSET),
|
||||
4);
|
||||
if (pc)
|
||||
{
|
||||
CORE_ADDR sp;
|
||||
|
||||
if (frame->next)
|
||||
/* If this isn't the top frame, the next frame must be for the
|
||||
signal handler itself. The sigcontext structure lives on
|
||||
the stack, right after the signum argument. */
|
||||
return frame->next->frame + 12;
|
||||
|
||||
/* This is the top frame. We'll have to find the address of the
|
||||
sigcontext structure by looking at the stack pointer. Keep
|
||||
in mind that the first instruction of the sigtramp code is
|
||||
"pop %eax". If the PC is at this instruction, adjust the
|
||||
returned value accordingly. */
|
||||
sp = read_register (SP_REGNUM);
|
||||
if (pc == frame->pc)
|
||||
return sp + 4;
|
||||
return sp;
|
||||
}
|
||||
|
||||
pc = i386_linux_rt_sigtramp_start (frame->pc);
|
||||
if (pc)
|
||||
{
|
||||
if (frame->next)
|
||||
/* If this isn't the top frame, the next frame must be for the
|
||||
signal handler itself. The sigcontext structure is part of
|
||||
the user context. A pointer to the user context is passed
|
||||
as the third argument to the signal handler. */
|
||||
return read_memory_integer (frame->next->frame + 16, 4) + 20;
|
||||
|
||||
/* This is the top frame. Again, use the stack pointer to find
|
||||
the address of the sigcontext structure. */
|
||||
return read_memory_integer (read_register (SP_REGNUM) + 8, 4) + 20;
|
||||
}
|
||||
|
||||
error ("Couldn't recognize signal trampoline.");
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>. */
|
||||
#define LINUX_SIGCONTEXT_PC_OFFSET (56)
|
||||
|
||||
/* Assuming FRAME is for a Linux sigtramp routine, return the saved
|
||||
stack pointer. The Linux kernel will set up a sigcontext structure
|
||||
immediately before the sigtramp routine on the stack. */
|
||||
program counter. */
|
||||
|
||||
CORE_ADDR
|
||||
i386_linux_sigtramp_saved_sp (frame)
|
||||
struct frame_info *frame;
|
||||
i386_linux_sigtramp_saved_pc (struct frame_info *frame)
|
||||
{
|
||||
CORE_ADDR pc;
|
||||
CORE_ADDR addr;
|
||||
addr = i386_linux_sigcontext_addr (frame);
|
||||
return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 4);
|
||||
}
|
||||
|
||||
pc = i386_linux_sigtramp_start (frame->pc);
|
||||
if (pc == 0)
|
||||
error ("i386_linux_sigtramp_saved_sp called when no sigtramp");
|
||||
return read_memory_integer ((pc
|
||||
- LINUX_SIGCONTEXT_SIZE
|
||||
+ LINUX_SIGCONTEXT_SP_OFFSET),
|
||||
4);
|
||||
/* Offset to saved SP in sigcontext, from <asm/sigcontext.h>. */
|
||||
#define LINUX_SIGCONTEXT_SP_OFFSET (28)
|
||||
|
||||
/* Assuming FRAME is for a Linux sigtramp routine, return the saved
|
||||
stack pointer. */
|
||||
|
||||
CORE_ADDR
|
||||
i386_linux_sigtramp_saved_sp (struct frame_info *frame)
|
||||
{
|
||||
CORE_ADDR addr;
|
||||
addr = i386_linux_sigcontext_addr (frame);
|
||||
return read_memory_integer (addr + LINUX_SIGCONTEXT_SP_OFFSET, 4);
|
||||
}
|
||||
|
||||
#endif /* I386_LINUX_SIGTRAMP */
|
||||
|
|
|
|||
Loading…
Reference in New Issue