Merge commit 'origin/master' into nptl

Conflicts:
	libc/misc/utmp/utent.c
	libc/sysdeps/linux/i386/bits/syscalls.h

Signed-off-by: Austin Foxley <austinf@cetoncorp.com>

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 */