diff options
Diffstat (limited to 'libc')
| -rw-r--r-- | libc/sysdeps/linux/i386/bits/syscalls.h | 96 |
1 files changed, 78 insertions, 18 deletions
diff --git a/libc/sysdeps/linux/i386/bits/syscalls.h b/libc/sysdeps/linux/i386/bits/syscalls.h index 09d48a2ff..0427d91cd 100644 --- a/libc/sysdeps/linux/i386/bits/syscalls.h +++ b/libc/sysdeps/linux/i386/bits/syscalls.h @@ -14,13 +14,36 @@ #include <errno.h> +#define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \ +({ \ + register unsigned int resultvar; \ + __asm__ __volatile__ ( \ + LOADARGS_##nr \ + "movl %1, %%eax\n\t" \ + "int $0x80\n\t" \ + RESTOREARGS_##nr \ + : "=a" (resultvar) \ + : "i" (name) ASMFMT_##nr(args) : "memory", "cc" \ + ); \ + (int) resultvar; \ +}) + + +#if 1 /* defined __PIC__ || defined __pic__ */ + +/* This code avoids pushing/popping ebx as much as possible. + * I think the main reason was that older GCCs had problems + * with proper saving/restoring of ebx if "b" constraint was used, + * which was breaking -fPIC code really badly. + * At least gcc 4.2.x seems to not need these tricks anymore, + * but this code is still useful because it often avoids + * using stack for saving ebx. + * Keeping it unconditionally enabled for now. + */ + /* We need some help from the assembler to generate optimal code. * We define some macros here which later will be used. */ -#if defined __SUPPORT_LD_DEBUG__ && defined __DOMULTI__ -#error LD debugging and DOMULTI are incompatible -#endif - __asm__ ( #ifdef __DOMULTI__ /* Protect against asm macro redefinition (happens in __DOMULTI__ mode). @@ -74,20 +97,6 @@ __asm__ ( #endif ); -#define INTERNAL_SYSCALL_NCS(name, err, nr, args...) \ -({ \ - register unsigned int resultvar; \ - __asm__ __volatile__ ( \ - LOADARGS_##nr \ - "movl %1, %%eax\n\t" \ - "int $0x80\n\t" \ - RESTOREARGS_##nr \ - : "=a" (resultvar) \ - : "i" (name) ASMFMT_##nr(args) : "memory", "cc" \ - ); \ - (int) resultvar; \ -}) - #define LOADARGS_0 #define LOADARGS_1 "bpushl .L__X'%k2, %k2\n\t" "bmovl .L__X'%k2, %k2\n\t" #define LOADARGS_2 LOADARGS_1 @@ -125,5 +134,56 @@ __asm__ ( #define ASMFMT_6(arg1, arg2, arg3, arg4, arg5, arg6) \ , "a" (arg1), "c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5), "m" (arg6) +#else /* !PIC */ + +/* Simpler code which just uses "b" constraint to load ebx. + * Seems to work with gc 4.2.x, and generates slightly smaller, + * but slightly slower code. Example (time syscall): + * + * - 8b 4c 24 04 mov 0x4(%esp),%ecx + * - 87 cb xchg %ecx,%ebx + * + 53 push %ebx + * + 8b 5c 24 08 mov 0x8(%esp),%ebx + * b8 0d 00 00 00 mov $0xd,%eax + * cd 80 int $0x80 + * - 87 cb xchg %ecx,%ebx + * + 5b pop %ebx + * c3 ret + * + * 2 bytes smaller, but uses stack via "push/pop ebx" + */ + +#define LOADARGS_0 +#define LOADARGS_1 +#define LOADARGS_2 +#define LOADARGS_3 +#define LOADARGS_4 +#define LOADARGS_5 +#define LOADARGS_6 "push %%ebp\n\t" "movl %7, %%ebp\n\t" + +#define RESTOREARGS_0 +#define RESTOREARGS_1 +#define RESTOREARGS_2 +#define RESTOREARGS_3 +#define RESTOREARGS_4 +#define RESTOREARGS_5 +#define RESTOREARGS_6 "pop %%ebp\n\t" + +#define ASMFMT_0() +#define ASMFMT_1(arg1) \ + , "b" (arg1) +#define ASMFMT_2(arg1, arg2) \ + , "b" (arg1), "c" (arg2) +#define ASMFMT_3(arg1, arg2, arg3) \ + , "b" (arg1), "c" (arg2), "d" (arg3) +#define ASMFMT_4(arg1, arg2, arg3, arg4) \ + , "b" (arg1), "c" (arg2), "d" (arg3), "S" (arg4) +#define ASMFMT_5(arg1, arg2, arg3, arg4, arg5) \ + , "b" (arg1), "c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5) +#define ASMFMT_6(arg1, arg2, arg3, arg4, arg5, arg6) \ + , "b" (arg1), "c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5), "m" (arg6) + +#endif /* !PIC */ + #endif /* __ASSEMBLER__ */ #endif /* _BITS_SYSCALLS_H */ |