* i386-tdep.c (LINUX_SIGTRAMP_INSN0, LINUX_SIGTRAMP_OFFSET0,
LINUX_SIGTRAMP_INSN1, LINUX_SIGTRAMP_OFFSET1, LINUX_SIGTRAMP_INSN2, LINUX_SIGTRAMP_OFFSET2, linux_sigtramp_code, LINUX_SIGTRAMP_LEN, i386_linux_sigtramp_start, LINUX_RT_SIGTRAMP_INSN0, LINUX_RT_SIGTRAMP_OFFSET0, LINUX_RT_SIGTRAMP_INSN1, LINUX_RT_SIGTRAMP_OFFSET1, linux_rt_sigtramp_code, LINUX_RT_SIGTRAMP_LEN, i386_linux_rt_sigtramp_start, i386_linux_in_sigtramp, i386_linux_sigcontext_addr, LINUX_SIGCONTEXT_PC_OFFSET, i386_linux_sigtramp_saved_pc, LINUX_SIGCONTEXT_SP_OFFSET, i386_linux_sigtramp_saved_sp): Deleted. These all implement Linux-specific signal trampoline detection, and should be moved to... * i386-linux-nat.c: ... here. * config/i386/tm-linux.h (I386_LINUX_SIGTRAMP): No need to define this any more, since we're not enabling OS-specific code in a OS-independent file.
This commit is contained in:
Jim Blandy
parent
dead141948
commit
11708b95a3
4 changed files with 265 additions and 258 deletions
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@ -1,3 +1,22 @@
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2000-03-16 Jim Blandy <jimb@redhat.com>
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* i386-tdep.c (LINUX_SIGTRAMP_INSN0, LINUX_SIGTRAMP_OFFSET0,
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LINUX_SIGTRAMP_INSN1, LINUX_SIGTRAMP_OFFSET1,
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LINUX_SIGTRAMP_INSN2, LINUX_SIGTRAMP_OFFSET2, linux_sigtramp_code,
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LINUX_SIGTRAMP_LEN, i386_linux_sigtramp_start,
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LINUX_RT_SIGTRAMP_INSN0, LINUX_RT_SIGTRAMP_OFFSET0,
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LINUX_RT_SIGTRAMP_INSN1, LINUX_RT_SIGTRAMP_OFFSET1,
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linux_rt_sigtramp_code, LINUX_RT_SIGTRAMP_LEN,
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i386_linux_rt_sigtramp_start, i386_linux_in_sigtramp,
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i386_linux_sigcontext_addr, LINUX_SIGCONTEXT_PC_OFFSET,
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i386_linux_sigtramp_saved_pc, LINUX_SIGCONTEXT_SP_OFFSET,
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i386_linux_sigtramp_saved_sp): Deleted. These all implement
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Linux-specific signal trampoline detection, and should be moved to...
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* i386-linux-nat.c: ... here.
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* config/i386/tm-linux.h (I386_LINUX_SIGTRAMP): No need to define
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this any more, since we're not enabling OS-specific code in a
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OS-independent file.
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2000-03-16 Eli Zaretskii <eliz@is.elta.co.il>
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* Makefile.in (go32-nat.o): Add prerequisites.
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@ -98,7 +98,6 @@ extern int i387_store_floating (PTR addr, int len, long double val);
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are used to identify this bit of code as a signal trampoline in
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order to support backtracing through calls to signal handlers. */
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#define I386_LINUX_SIGTRAMP
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#define IN_SIGTRAMP(pc, name) i386_linux_in_sigtramp (pc, name)
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extern int i386_linux_in_sigtramp (CORE_ADDR, char *);
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@ -1041,6 +1041,252 @@ i386_linux_skip_solib_resolver (CORE_ADDR pc)
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return 0;
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}
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/* Recognizing signal handler frames. */
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/* Linux has two flavors of signals. Normal signal handlers, and
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"realtime" (RT) signals. The RT signals can provide additional
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information to the signal handler if the SA_SIGINFO flag is set
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when establishing a signal handler using `sigaction'. It is not
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unlikely that future versions of Linux will support SA_SIGINFO for
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normal signals too. */
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/* When the i386 Linux kernel calls a signal handler and the
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SA_RESTORER flag isn't set, the return address points to a bit of
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code on the stack. This function returns whether the PC appears to
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be within this bit of code.
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The instruction sequence for normal signals is
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pop %eax
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mov $0x77,%eax
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int $0x80
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or 0x58 0xb8 0x77 0x00 0x00 0x00 0xcd 0x80.
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Checking for the code sequence should be somewhat reliable, because
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the effect is to call the system call sigreturn. This is unlikely
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to occur anywhere other than a signal trampoline.
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It kind of sucks that we have to read memory from the process in
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order to identify a signal trampoline, but there doesn't seem to be
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any other way. The IN_SIGTRAMP macro in tm-linux.h arranges to
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only call us if no function name could be identified, which should
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be the case since the code is on the stack.
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Detection of signal trampolines for handlers that set the
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SA_RESTORER flag is in general not possible. Unfortunately this is
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what the GNU C Library has been doing for quite some time now.
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However, as of version 2.1.2, the GNU C Library uses signal
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trampolines (named __restore and __restore_rt) that are identical
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to the ones used by the kernel. Therefore, these trampolines are
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supported too. */
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#define LINUX_SIGTRAMP_INSN0 (0x58) /* pop %eax */
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#define LINUX_SIGTRAMP_OFFSET0 (0)
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#define LINUX_SIGTRAMP_INSN1 (0xb8) /* mov $NNNN,%eax */
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#define LINUX_SIGTRAMP_OFFSET1 (1)
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#define LINUX_SIGTRAMP_INSN2 (0xcd) /* int */
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#define LINUX_SIGTRAMP_OFFSET2 (6)
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static const unsigned char linux_sigtramp_code[] =
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{
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LINUX_SIGTRAMP_INSN0, /* pop %eax */
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LINUX_SIGTRAMP_INSN1, 0x77, 0x00, 0x00, 0x00, /* mov $0x77,%eax */
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LINUX_SIGTRAMP_INSN2, 0x80 /* int $0x80 */
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};
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#define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
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/* If PC is in a sigtramp routine, return the address of the start of
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the routine. Otherwise, return 0. */
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static CORE_ADDR
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i386_linux_sigtramp_start (CORE_ADDR pc)
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{
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unsigned char buf[LINUX_SIGTRAMP_LEN];
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/* We only recognize a signal trampoline if PC is at the start of
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one of the three instructions. We optimize for finding the PC at
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the start, as will be the case when the trampoline is not the
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first frame on the stack. We assume that in the case where the
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PC is not at the start of the instruction sequence, there will be
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a few trailing readable bytes on the stack. */
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if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
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return 0;
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if (buf[0] != LINUX_SIGTRAMP_INSN0)
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{
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int adjust;
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switch (buf[0])
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{
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case LINUX_SIGTRAMP_INSN1:
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adjust = LINUX_SIGTRAMP_OFFSET1;
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break;
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case LINUX_SIGTRAMP_INSN2:
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adjust = LINUX_SIGTRAMP_OFFSET2;
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break;
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default:
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return 0;
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}
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pc -= adjust;
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if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
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return 0;
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}
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if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)
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return 0;
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return pc;
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}
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/* This function does the same for RT signals. Here the instruction
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sequence is
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mov $0xad,%eax
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int $0x80
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or 0xb8 0xad 0x00 0x00 0x00 0xcd 0x80.
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The effect is to call the system call rt_sigreturn. */
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#define LINUX_RT_SIGTRAMP_INSN0 (0xb8) /* mov $NNNN,%eax */
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#define LINUX_RT_SIGTRAMP_OFFSET0 (0)
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#define LINUX_RT_SIGTRAMP_INSN1 (0xcd) /* int */
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#define LINUX_RT_SIGTRAMP_OFFSET1 (5)
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static const unsigned char linux_rt_sigtramp_code[] =
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{
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LINUX_RT_SIGTRAMP_INSN0, 0xad, 0x00, 0x00, 0x00, /* mov $0xad,%eax */
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LINUX_RT_SIGTRAMP_INSN1, 0x80 /* int $0x80 */
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};
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#define LINUX_RT_SIGTRAMP_LEN (sizeof linux_rt_sigtramp_code)
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/* If PC is in a RT sigtramp routine, return the address of the start
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of the routine. Otherwise, return 0. */
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static CORE_ADDR
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i386_linux_rt_sigtramp_start (CORE_ADDR pc)
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{
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unsigned char buf[LINUX_RT_SIGTRAMP_LEN];
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/* We only recognize a signal trampoline if PC is at the start of
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one of the two instructions. We optimize for finding the PC at
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the start, as will be the case when the trampoline is not the
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first frame on the stack. We assume that in the case where the
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PC is not at the start of the instruction sequence, there will be
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a few trailing readable bytes on the stack. */
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if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
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return 0;
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if (buf[0] != LINUX_RT_SIGTRAMP_INSN0)
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{
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if (buf[0] != LINUX_RT_SIGTRAMP_INSN1)
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return 0;
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pc -= LINUX_RT_SIGTRAMP_OFFSET1;
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if (read_memory_nobpt (pc, (char *) buf, LINUX_RT_SIGTRAMP_LEN) != 0)
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return 0;
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}
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if (memcmp (buf, linux_rt_sigtramp_code, LINUX_RT_SIGTRAMP_LEN) != 0)
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return 0;
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return pc;
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}
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/* Return whether PC is in a Linux sigtramp routine. */
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int
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i386_linux_in_sigtramp (CORE_ADDR pc, char *name)
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{
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if (name)
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return STREQ ("__restore", name) || STREQ ("__restore_rt", name);
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return (i386_linux_sigtramp_start (pc) != 0
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|| i386_linux_rt_sigtramp_start (pc) != 0);
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}
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/* Assuming FRAME is for a Linux sigtramp routine, return the address
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of the associated sigcontext structure. */
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CORE_ADDR
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i386_linux_sigcontext_addr (struct frame_info *frame)
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{
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CORE_ADDR pc;
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pc = i386_linux_sigtramp_start (frame->pc);
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if (pc)
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{
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CORE_ADDR sp;
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if (frame->next)
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/* If this isn't the top frame, the next frame must be for the
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signal handler itself. The sigcontext structure lives on
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the stack, right after the signum argument. */
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return frame->next->frame + 12;
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/* This is the top frame. We'll have to find the address of the
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sigcontext structure by looking at the stack pointer. Keep
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in mind that the first instruction of the sigtramp code is
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"pop %eax". If the PC is at this instruction, adjust the
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returned value accordingly. */
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sp = read_register (SP_REGNUM);
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if (pc == frame->pc)
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return sp + 4;
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return sp;
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}
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pc = i386_linux_rt_sigtramp_start (frame->pc);
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if (pc)
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{
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if (frame->next)
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/* If this isn't the top frame, the next frame must be for the
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signal handler itself. The sigcontext structure is part of
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the user context. A pointer to the user context is passed
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as the third argument to the signal handler. */
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return read_memory_integer (frame->next->frame + 16, 4) + 20;
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/* This is the top frame. Again, use the stack pointer to find
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the address of the sigcontext structure. */
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return read_memory_integer (read_register (SP_REGNUM) + 8, 4) + 20;
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}
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error ("Couldn't recognize signal trampoline.");
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return 0;
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}
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/* Offset to saved PC in sigcontext, from <asm/sigcontext.h>. */
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#define LINUX_SIGCONTEXT_PC_OFFSET (56)
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/* Assuming FRAME is for a Linux sigtramp routine, return the saved
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program counter. */
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CORE_ADDR
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i386_linux_sigtramp_saved_pc (struct frame_info *frame)
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{
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CORE_ADDR addr;
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addr = i386_linux_sigcontext_addr (frame);
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return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_OFFSET, 4);
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}
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/* Offset to saved SP in sigcontext, from <asm/sigcontext.h>. */
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#define LINUX_SIGCONTEXT_SP_OFFSET (28)
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/* Assuming FRAME is for a Linux sigtramp routine, return the saved
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stack pointer. */
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CORE_ADDR
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i386_linux_sigtramp_saved_sp (struct frame_info *frame)
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{
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CORE_ADDR addr;
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addr = i386_linux_sigcontext_addr (frame);
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return read_memory_integer (addr + LINUX_SIGCONTEXT_SP_OFFSET, 4);
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}
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/* Register that we are able to handle Linux ELF core file formats. */
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|
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257
gdb/i386-tdep.c
257
gdb/i386-tdep.c
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@ -779,263 +779,6 @@ i386v4_sigtramp_saved_pc (frame)
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}
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#endif /* I386V4_SIGTRAMP_SAVED_PC */
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#ifdef I386_LINUX_SIGTRAMP
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/* Linux has two flavors of signals. Normal signal handlers, and
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"realtime" (RT) signals. The RT signals can provide additional
|
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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. */
|
||||
|
||||
/* 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
|
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int $0x80
|
||||
or 0x58 0xb8 0x77 0x00 0x00 0x00 0xcd 0x80.
|
||||
|
||||
Checking for the code sequence should be somewhat reliable, because
|
||||
the effect is to call the system call sigreturn. This is unlikely
|
||||
to occur anywhere other than a signal trampoline.
|
||||
|
||||
It kind of sucks that we have to read memory from the process in
|
||||
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.
|
||||
|
||||
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)
|
||||
#define LINUX_SIGTRAMP_INSN1 (0xb8) /* mov $NNNN,%eax */
|
||||
#define LINUX_SIGTRAMP_OFFSET1 (1)
|
||||
#define LINUX_SIGTRAMP_INSN2 (0xcd) /* int */
|
||||
#define LINUX_SIGTRAMP_OFFSET2 (6)
|
||||
|
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static const unsigned char linux_sigtramp_code[] =
|
||||
{
|
||||
LINUX_SIGTRAMP_INSN0, /* pop %eax */
|
||||
LINUX_SIGTRAMP_INSN1, 0x77, 0x00, 0x00, 0x00, /* mov $0x77,%eax */
|
||||
LINUX_SIGTRAMP_INSN2, 0x80 /* int $0x80 */
|
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};
|
||||
|
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#define LINUX_SIGTRAMP_LEN (sizeof linux_sigtramp_code)
|
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|
||||
/* If PC is in a sigtramp routine, return the address of the start of
|
||||
the routine. Otherwise, return 0. */
|
||||
|
||||
static CORE_ADDR
|
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i386_linux_sigtramp_start (CORE_ADDR pc)
|
||||
{
|
||||
unsigned char buf[LINUX_SIGTRAMP_LEN];
|
||||
|
||||
/* We only recognize a signal trampoline if PC is at the start of
|
||||
one of the three 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_SIGTRAMP_LEN) != 0)
|
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return 0;
|
||||
|
||||
if (buf[0] != LINUX_SIGTRAMP_INSN0)
|
||||
{
|
||||
int adjust;
|
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|
||||
switch (buf[0])
|
||||
{
|
||||
case LINUX_SIGTRAMP_INSN1:
|
||||
adjust = LINUX_SIGTRAMP_OFFSET1;
|
||||
break;
|
||||
case LINUX_SIGTRAMP_INSN2:
|
||||
adjust = LINUX_SIGTRAMP_OFFSET2;
|
||||
break;
|
||||
default:
|
||||
return 0;
|
||||
}
|
||||
|
||||
pc -= adjust;
|
||||
|
||||
if (read_memory_nobpt (pc, (char *) buf, LINUX_SIGTRAMP_LEN) != 0)
|
||||
return 0;
|
||||
}
|
||||
|
||||
if (memcmp (buf, linux_sigtramp_code, LINUX_SIGTRAMP_LEN) != 0)
|
||||
return 0;
|
||||
|
||||
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_in_sigtramp (CORE_ADDR pc, char *name)
|
||||
{
|
||||
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 address
|
||||
of the associated sigcontext structure. */
|
||||
|
||||
CORE_ADDR
|
||||
i386_linux_sigcontext_addr (struct frame_info *frame)
|
||||
{
|
||||
CORE_ADDR pc;
|
||||
|
||||
pc = i386_linux_sigtramp_start (frame->pc);
|
||||
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
|
||||
program counter. */
|
||||
|
||||
CORE_ADDR
|
||||
i386_linux_sigtramp_saved_pc (struct frame_info *frame)
|
||||
{
|
||||
CORE_ADDR addr;
|
||||
addr = i386_linux_sigcontext_addr (frame);
|
||||
return read_memory_integer (addr + LINUX_SIGCONTEXT_PC_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);
|
||||
}
|
||||
|
||||
/* Immediately after a function call, return the saved pc. */
|
||||
|
||||
CORE_ADDR
|
||||
i386_linux_saved_pc_after_call (struct frame_info *frame)
|
||||
{
|
||||
if (frame->signal_handler_caller)
|
||||
return i386_linux_sigtramp_saved_pc (frame);
|
||||
|
||||
return read_memory_integer (read_register (SP_REGNUM), 4);
|
||||
}
|
||||
|
||||
#endif /* I386_LINUX_SIGTRAMP */
|
||||
|
||||
#ifdef STATIC_TRANSFORM_NAME
|
||||
/* SunPRO encodes the static variables. This is not related to C++ mangling,
|
||||
|
|
|
|||
Loading…
Reference in a new issue