diff options
| author | Mike Frysinger <vapier@gentoo.org> | 2006-01-31 00:33:26 +0000 |
|---|---|---|
| committer | Mike Frysinger <vapier@gentoo.org> | 2006-01-31 00:33:26 +0000 |
| commit | fa30ad140d5f298befc3c59524a4640c8022c705 (patch) | |
| tree | 06571101de8cb1ce03e67ba24dfb5c2f86e19be0 | |
| parent | 8504c3b4d833a77dc3384a0af36a85aeb36d9dcc (diff) | |
John Bowler writes in Bug 385:
This is a work round for a fairly serious GCC compiler bug - when
the syscall assembler overwrites r7 (required on thumb) the
compiler fails to protect the register when it is using it as a
frame pointer.
| -rw-r--r-- | libc/sysdeps/linux/arm/bits/syscalls.h | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/libc/sysdeps/linux/arm/bits/syscalls.h b/libc/sysdeps/linux/arm/bits/syscalls.h index c6ab3ecf7..d25d1824e 100644 --- a/libc/sysdeps/linux/arm/bits/syscalls.h +++ b/libc/sysdeps/linux/arm/bits/syscalls.h @@ -141,6 +141,11 @@ return (type) (INLINE_SYSCALL(name, 7, arg1, arg2, arg3, arg4, arg5, arg6, arg7) } \ (int) _sys_result; }) #else +#if 0 +/* This doesn't work because GCC uses r7 as a frame pointer in + * some cases and doesn't notice that the _r7 value changes + * it, resulting in mysterious crashes after the SWI. + */ #define INTERNAL_SYSCALL(name, err, nr, args...) \ ({ unsigned int _sys_result; \ { \ @@ -154,6 +159,28 @@ return (type) (INLINE_SYSCALL(name, 7, arg1, arg2, arg3, arg4, arg5, arg6, arg7) _sys_result = _a1; \ } \ (int) _sys_result; }) +#else +/* So hide the use of r7 from the compiler, this would be a lot + * easier but for the fact that the syscalls can exceed 255. + * For the moment the LOAD_ARG_7 is sacrificed. + */ +#define INTERNAL_SYSCALL(name, err, nr, args...) \ + ({ unsigned int _sys_result; \ + { \ + register int _a1 asm ("a1"); \ + LOAD_ARGS_##nr (args) \ + register int _v3 asm ("v3") = (int) (SYS_ify(name)); \ + asm volatile ("push {r7}\n" \ + "\tmov r7, v3\n" \ + "\tswi 0 @ syscall " #name "\n" \ + "\tpop {r7}" \ + : "=r" (_a1) \ + : "r" (_v3) ASM_ARGS_##nr \ + : "memory"); \ + _sys_result = _a1; \ + } \ + (int) _sys_result; }) +#endif #endif #endif /* !defined(__ARM_EABI__) */ |