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Re: PATCH: Add x32 support to tests/backtrace.c
- From: H.J. Lu <hjl dot tools at gmail dot com>
- To: elfutils-devel at lists dot fedorahosted dot org
- Date: Thu, 12 Mar 2015 16:28:07 -0700
- Subject: Re: PATCH: Add x32 support to tests/backtrace.c
On Thu, Mar 12, 2015 at 3:07 PM, Roland McGrath <roland@hack.frob.com> wrote:
> GETREGS/SETREGS works fine everywhere. Just use it unconditionally.
This patch uses PTRACE_GETREGS/PTRACE_SETREGS to update rip.
--
H.J.
From 75b3cb18bbc9cbe51142c9ca314c69cb54cb9bba Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Thu, 12 Mar 2015 12:14:43 -0700
Subject: [PATCH 2/3] Use PTRACE_GETREGS/PTRACE_SETREGS to update rip
Use PTRACE_POKEUSER to update rip is unsupported for x32. We should use
PTRACE_GETREGS/PTRACE_SETREGS to update rip.
---
tests/backtrace.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/tests/backtrace.c b/tests/backtrace.c
index ab4110f..05cc0f6 100644
--- a/tests/backtrace.c
+++ b/tests/backtrace.c
@@ -260,9 +260,13 @@ prepare_thread (pid_t pid2 __attribute__ ((unused)),
abort ();
#else /* x86_64 */
long l;
+ struct user_regs_struct user_regs;
errno = 0;
- l = ptrace (PTRACE_POKEUSER, pid2,
- (void *) (intptr_t) offsetof (struct user_regs_struct, rip), jmp);
+ l = ptrace (PTRACE_GETREGS, pid2, 0, (intptr_t) &user_regs);
+ assert_perror (errno);
+ assert (l == 0);
+ user_regs.rip = (intptr_t) jmp;
+ l = ptrace (PTRACE_SETREGS, pid2, 0, (intptr_t) &user_regs);
assert_perror (errno);
assert (l == 0);
l = ptrace (PTRACE_CONT, pid2, NULL, (void *) (intptr_t) SIGUSR2);
@@ -381,7 +385,7 @@ exec_dump (const char *exec)
#ifndef __x86_64__
is_x86_64_native = false;
#else /* __x86_64__ */
- is_x86_64_native = ehdr->e_ident[EI_CLASS] == ELFCLASS64;
+ is_x86_64_native = ehdr->e_machine == EM_X86_64;
#endif /* __x86_64__ */
void (*jmp) (void) = 0;
if (is_x86_64_native)
--
1.9.3