From 40c31709c6a51926fcb409611caa52b2da6515c0 Mon Sep 17 00:00:00 2001 From: Pedro Alves Date: Tue, 26 Jul 2016 19:35:40 +0100 Subject: [PATCH] Fix PR gdb/20413 - x32: linux_ptrace_test_ret_to_nx: Cannot PTRACE_PEEKUSER 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 * nat/linux-ptrace.c: Include "gregset.h". (linux_ptrace_test_ret_to_nx): Use PTRACE_GETREGS instead of PTRACE_PEEKUSER. --- gdb/ChangeLog | 6 ++++++ gdb/nat/linux-ptrace.c | 22 ++++++++++------------ 2 files changed, 16 insertions(+), 12 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 3a5e8707a3c..2f3710d9e49 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,9 @@ +2016-07-26 Pedro Alves + + * 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 * amd64-linux-nat.c (amd64_linux_siginfo_fixup): Rename 'native' diff --git a/gdb/nat/linux-ptrace.c b/gdb/nat/linux-ptrace.c index 0eaf9a30ff4..980ed53c73f 100644 --- a/gdb/nat/linux-ptrace.c +++ b/gdb/nat/linux-ptrace.c @@ -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) ®s) < 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, -- 2.30.2