[PATCH] gdb: x86: fix x32 builds with inline asm

Mike Frysinger
2013-01-08T14:59:07Z

The inline assembly fails with x32 targets due to pushq used with a 32bit
register. Since the assembler can do the right thing with a "push" insn
and a 32bit or 64bit register (i.e. it'll pushl or pushq as needed), just
use that insn.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>

2012-01-08 Mike Frysinger <vapier@gentoo.org>

* common/linux-ptrace.c (linux_ptrace_test_ret_to_nx): Change pushl
to push in i386 inline asm and %esp to sp. Delete __i386__ check
and __x86_64__ inline asm.
---
Note: I'm not 100% on the "sp" constraint. Seems to work, and reading
the gcc constraints list looks like it aliases sp/esp/rsp to the same
thing.

gdb/common/linux-ptrace.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)

diff --git a/gdb/common/linux-ptrace.c b/gdb/common/linux-ptrace.c
index 761ef59..abb502c 100644
--- a/gdb/common/linux-ptrace.c
+++ b/gdb/common/linux-ptrace.c
@@ -103,21 +103,11 @@ linux_ptrace_test_ret_to_nx (void)
strerror (errno));
else
{
-#if defined __i386__
- asm volatile ("pushl %0;"
- ".globl linux_ptrace_test_ret_to_nx_instr;"
- "linux_ptrace_test_ret_to_nx_instr:"
- "ret"
- : : "r" (return_address) : "%esp", "memory");
-#elif defined __x86_64__
- asm volatile ("pushq %0;"
+ asm volatile ("push %0;"
".globl linux_ptrace_test_ret_to_nx_instr;"
"linux_ptrace_test_ret_to_nx_instr:"
"ret"
- : : "r" (return_address) : "%rsp", "memory");
-#else
-# error "!__i386__ && !__x86_64__"
-#endif
+ : : "r" (return_address) : "sp", "memory");
gdb_assert_not_reached ("asm block did not terminate");
}

--
1.8.0.2