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-rw-r--r--libc/sysdeps/linux/i386/bits/syscalls.h263
1 files changed, 155 insertions, 108 deletions
diff --git a/libc/sysdeps/linux/i386/bits/syscalls.h b/libc/sysdeps/linux/i386/bits/syscalls.h
index f9ea54ac7..0427d91cd 100644
--- a/libc/sysdeps/linux/i386/bits/syscalls.h
+++ b/libc/sysdeps/linux/i386/bits/syscalls.h
@@ -1,142 +1,189 @@
#ifndef _BITS_SYSCALLS_H
#define _BITS_SYSCALLS_H
+
#ifndef _SYSCALL_H
# error "Never use <bits/syscalls.h> directly; include <sys/syscall.h> instead."
#endif
/*
- Some of the sneaky macros in the code were taken from
- glibc-2.2.5/sysdeps/unix/sysv/linux/i386/sysdep.h
-*/
+ * Some of the sneaky macros in the code were taken from
+ * glibc-2.2.5/sysdeps/unix/sysv/linux/i386/sysdep.h
+ */
#ifndef __ASSEMBLER__
#include <errno.h>
-/* We need some help from the assembler to generate optimal code. We
- define some macros here which later will be used. */
+#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 defined __SUPPORT_LD_DEBUG__ && defined __DOMULTI__
-#error LD debugging and DOMULTI are incompatible
-#endif
+#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. */
+
+__asm__ (
#ifdef __DOMULTI__
-__asm__ (".L__X'%ebx = 1\n\t"
- ".L__X'%ecx = 2\n\t"
- ".L__X'%edx = 2\n\t"
- ".L__X'%eax = 3\n\t"
- ".L__X'%esi = 3\n\t"
- ".L__X'%edi = 3\n\t"
- ".L__X'%ebp = 3\n\t"
- ".L__X'%esp = 3\n\t"
- ".ifndef _BITS_SYSCALLS_ASM\n\t"
- ".set _BITS_SYSCALLS_ASM,1\n\t"
- ".macro bpushl name reg\n\t"
- ".if 1 - \\name\n\t"
- ".if 2 - \\name\n\t"
- "pushl %ebx\n\t"
- ".else\n\t"
- "xchgl \\reg, %ebx\n\t"
- ".endif\n\t"
- ".endif\n\t"
- ".endm\n\t"
- ".macro bpopl name reg\n\t"
- ".if 1 - \\name\n\t"
- ".if 2 - \\name\n\t"
- "popl %ebx\n\t"
- ".else\n\t"
- "xchgl \\reg, %ebx\n\t"
- ".endif\n\t"
- ".endif\n\t"
- ".endm\n\t"
- ".macro bmovl name reg\n\t"
- ".if 1 - \\name\n\t"
- ".if 2 - \\name\n\t"
- "movl \\reg, %ebx\n\t"
- ".endif\n\t"
- ".endif\n\t"
- ".endm\n\t"
- ".endif\n\t");
-#else
-__asm__ (".L__X'%ebx = 1\n\t"
- ".L__X'%ecx = 2\n\t"
- ".L__X'%edx = 2\n\t"
- ".L__X'%eax = 3\n\t"
- ".L__X'%esi = 3\n\t"
- ".L__X'%edi = 3\n\t"
- ".L__X'%ebp = 3\n\t"
- ".L__X'%esp = 3\n\t"
- ".macro bpushl name reg\n\t"
- ".if 1 - \\name\n\t"
- ".if 2 - \\name\n\t"
- "pushl %ebx\n\t"
- ".else\n\t"
- "xchgl \\reg, %ebx\n\t"
- ".endif\n\t"
- ".endif\n\t"
- ".endm\n\t"
- ".macro bpopl name reg\n\t"
- ".if 1 - \\name\n\t"
- ".if 2 - \\name\n\t"
- "popl %ebx\n\t"
- ".else\n\t"
- "xchgl \\reg, %ebx\n\t"
- ".endif\n\t"
- ".endif\n\t"
- ".endm\n\t"
- ".macro bmovl name reg\n\t"
- ".if 1 - \\name\n\t"
- ".if 2 - \\name\n\t"
- "movl \\reg, %ebx\n\t"
- ".endif\n\t"
- ".endif\n\t"
- ".endm\n\t");
+ /* Protect against asm macro redefinition (happens in __DOMULTI__ mode).
+ * Unfortunately, it ends up visible in .o files. */
+ ".ifndef _BITS_SYSCALLS_ASM\n\t"
+ ".set _BITS_SYSCALLS_ASM,1\n\t"
#endif
+ ".L__X'%ebx = 1\n\t"
+ ".L__X'%ecx = 2\n\t"
+ ".L__X'%edx = 2\n\t"
+ ".L__X'%eax = 3\n\t"
+ ".L__X'%esi = 3\n\t"
+ ".L__X'%edi = 3\n\t"
+ ".L__X'%ebp = 3\n\t"
+ ".L__X'%esp = 3\n\t"
-#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) \
- : "g" (name) ASMFMT_##nr(args) : "memory", "cc"); \
- (int) resultvar; })
+ /* Loading param #1 (ebx) is done by loading it into
+ * another register, and then performing bpushl+bmovl,
+ * since we must preserve ebx */
+
+ ".macro bpushl name reg\n\t"
+ ".if 1 - \\name\n\t" /* if reg!=ebx... */
+ ".if 2 - \\name\n\t" /* if reg can't be clobbered... */
+ "pushl %ebx\n\t" /* save ebx on stack */
+ ".else\n\t"
+ "xchgl \\reg, %ebx\n\t" /* else save ebx in reg, and load reg to ebx */
+ ".endif\n\t"
+ ".endif\n\t"
+ ".endm\n\t"
+
+ ".macro bmovl name reg\n\t"
+ ".if 1 - \\name\n\t"
+ ".if 2 - \\name\n\t" /* if reg can't be clobbered... */
+ "movl \\reg, %ebx\n\t" /* load reg to ebx */
+ ".endif\n\t"
+ ".endif\n\t"
+ ".endm\n\t"
+
+ ".macro bpopl name reg\n\t"
+ ".if 1 - \\name\n\t"
+ ".if 2 - \\name\n\t" /* if reg can't be clobbered... */
+ "popl %ebx\n\t" /* restore ebx from stack */
+ ".else\n\t"
+ "xchgl \\reg, %ebx\n\t" /* else restore ebx from reg */
+ ".endif\n\t"
+ ".endif\n\t"
+ ".endm\n\t"
+
+#ifdef __DOMULTI__
+ ".endif\n\t" /* _BITS_SYSCALLS_ASM */
+#endif
+);
#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
-#define LOADARGS_3 LOADARGS_1
-#define LOADARGS_4 LOADARGS_1
-#define LOADARGS_5 LOADARGS_1
-#define LOADARGS_6 LOADARGS_1 "push %%ebp ; movl %7, %%ebp\n\t"
+#define LOADARGS_1 "bpushl .L__X'%k2, %k2\n\t" "bmovl .L__X'%k2, %k2\n\t"
+#define LOADARGS_2 LOADARGS_1
+#define LOADARGS_3 LOADARGS_1
+#define LOADARGS_4 LOADARGS_1
+#define LOADARGS_5 LOADARGS_1
+#define LOADARGS_6 LOADARGS_1 "push %%ebp\n\t" "movl %7, %%ebp\n\t"
#define RESTOREARGS_0
-#define RESTOREARGS_1 \
- "bpopl .L__X'%k2, %k2\n\t"
-#define RESTOREARGS_2 RESTOREARGS_1
-#define RESTOREARGS_3 RESTOREARGS_1
-#define RESTOREARGS_4 RESTOREARGS_1
-#define RESTOREARGS_5 RESTOREARGS_1
-#define RESTOREARGS_6 "pop %%ebp\n\t" RESTOREARGS_1
+#define RESTOREARGS_1 "bpopl .L__X'%k2, %k2\n\t"
+#define RESTOREARGS_2 RESTOREARGS_1
+#define RESTOREARGS_3 RESTOREARGS_1
+#define RESTOREARGS_4 RESTOREARGS_1
+#define RESTOREARGS_5 RESTOREARGS_1
+#define RESTOREARGS_6 "pop %%ebp\n\t" RESTOREARGS_1
#define ASMFMT_0()
+/* "acdSD" constraint would work too, but "SD" would use esi/edi and cause
+ * them to be pushed/popped by compiler, "a" would use eax and cause ebx
+ * to be saved/restored on stack, not in register. Narrowing choice down
+ * to "ecx or edx" results in smaller and faster code: */
#define ASMFMT_1(arg1) \
- , "acdSD" (arg1)
+ , "cd" (arg1)
+/* Can use "adSD" constraint here: */
#define ASMFMT_2(arg1, arg2) \
- , "adSD" (arg1), "c" (arg2)
+ , "d" (arg1), "c" (arg2)
+/* Can use "aSD" constraint here: */
#define ASMFMT_3(arg1, arg2, arg3) \
- , "aSD" (arg1), "c" (arg2), "d" (arg3)
+ , "a" (arg1), "c" (arg2), "d" (arg3)
+/* Can use "aD" constraint here: */
#define ASMFMT_4(arg1, arg2, arg3, arg4) \
- , "aD" (arg1), "c" (arg2), "d" (arg3), "S" (arg4)
+ , "a" (arg1), "c" (arg2), "d" (arg3), "S" (arg4)
#define ASMFMT_5(arg1, arg2, arg3, arg4, arg5) \
, "a" (arg1), "c" (arg2), "d" (arg3), "S" (arg4), "D" (arg5)
#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 */
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-04 16:09:31 +0000