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Fix PR gdb/20413 - x32: linux_ptrace_test_ret_to_nx: Cannot PTRACE_PEEKUSER

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An x32 gdb always issues this warning:

 (gdb) start
 Temporary breakpoint 1 at 0x4043e9: file foo.c, line 25.
 Starting program: a.out
 warning: linux_ptrace_test_ret_to_nx: Cannot PTRACE_PEEKUSER: Input/output error

 Temporary breakpoint 1, main (argc=1, argv=0xffffd544) at foo.c:25
 25      {
 (gdb)

As described in Linux commit 55283e253771 (x32: Add ptrace for x32):

    [...] PTRACE_PEEKUSR and PTRACE_POKEUSR are only allowed to access
    segment and debug registers. [...]

The fix is to use PTRACE_GETREGS instead.

gdb/ChangeLog:
2016-07-26  Pedro Alves  <palves@redhat.com>

	* nat/linux-ptrace.c: Include "gregset.h".
	(linux_ptrace_test_ret_to_nx): Use PTRACE_GETREGS instead of
	PTRACE_PEEKUSER.
This commit is contained in:
Pedro Alves 2016-07-26 19:35:40 +01:00
parent 9cf12d57c5
commit 40c31709c6
2 changed files with 16 additions and 12 deletions
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6
gdb/ChangeLog
View file

@ -1,3 +1,9 @@
2016-07-26 Pedro Alves <palves@redhat.com>
* nat/linux-ptrace.c: Include "gregset.h".
(linux_ptrace_test_ret_to_nx): Use PTRACE_GETREGS instead of
PTRACE_PEEKUSER.
2016-07-26 Pedro Alves <palves@redhat.com>
* amd64-linux-nat.c (amd64_linux_siginfo_fixup): Rename 'native'

22
gdb/nat/linux-ptrace.c
View file

@ -23,6 +23,7 @@
#include "buffer.h"
#include "gdb_wait.h"
#include "gdb_ptrace.h"
#include "gregset.h"
/* Stores the ptrace options supported by the running kernel.
A value of -1 means we did not check for features yet. A value
@ -100,6 +101,7 @@ linux_ptrace_test_ret_to_nx (void)
gdb_byte *return_address, *pc;
long l;
int status, kill_status;
elf_gregset_t regs;
return_address
= (gdb_byte *) mmap (NULL, 2, PROT_READ | PROT_WRITE,
@ -188,23 +190,19 @@ linux_ptrace_test_ret_to_nx (void)
return;
}
errno = 0;
if (ptrace (PTRACE_GETREGS, child, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) &regs) < 0)
{
warning (_("linux_ptrace_test_ret_to_nx: Cannot PTRACE_GETREGS: %s"),
safe_strerror (errno));
}
#if defined __i386__
l = ptrace (PTRACE_PEEKUSER, child, (PTRACE_TYPE_ARG3) (uintptr_t) (EIP * 4),
(PTRACE_TYPE_ARG4) NULL);
pc = (gdb_byte *) (uintptr_t) regs[EIP];
#elif defined __x86_64__
l = ptrace (PTRACE_PEEKUSER, child, (PTRACE_TYPE_ARG3) (uintptr_t) (RIP * 8),
(PTRACE_TYPE_ARG4) NULL);
pc = (gdb_byte *) (uintptr_t) regs[RIP];
#else
# error "!__i386__ && !__x86_64__"
#endif
if (errno != 0)
{
warning (_("linux_ptrace_test_ret_to_nx: Cannot PTRACE_PEEKUSER: %s"),
safe_strerror (errno));
return;
}
pc = (gdb_byte *) (uintptr_t) l;
kill (child, SIGKILL);
ptrace (PTRACE_KILL, child, (PTRACE_TYPE_ARG3) NULL,