[PATCH v1 04/11] tools/nolibc: x86-64: Use appropriate register constraints if exist
From: Ammar Faizi
Date: Thu Mar 24 2022 - 03:32:01 EST
Use appropriate register constraints if exist. Don't use register
variables for all inputs.
Register variables with "r" constraint should be used when we need to
pass data through a specific register to extended inline assembly that
doesn't have a specific register constraint associated with it (anything
outside %rax, %rbx, %rcx, %rdx, %rsi, %rdi).
It also simplifies the macro definition.
Link: https://lore.kernel.org/lkml/3d2cfdeecddc45dc8e4beada305b5948@xxxxxxxxxxxxxxxx
Suggested-by: David Laight <David.Laight@xxxxxxxxxx>
Signed-off-by: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>
---
tools/include/nolibc/arch-x86_64.h | 202 +++++++++++++----------------
1 file changed, 91 insertions(+), 111 deletions(-)
diff --git a/tools/include/nolibc/arch-x86_64.h b/tools/include/nolibc/arch-x86_64.h
index afc50f84a036..3067f553c03c 100644
--- a/tools/include/nolibc/arch-x86_64.h
+++ b/tools/include/nolibc/arch-x86_64.h
@@ -65,129 +65,109 @@ struct sys_stat_struct {
*
*/
-#define my_syscall0(num) \
-({ \
- long _ret; \
- register long _num __asm__("rax") = (num); \
- \
- __asm__ volatile ( \
- "syscall\n" \
- : "=a"(_ret) \
- : "0"(_num) \
- : "rcx", "r11", "memory", "cc" \
- ); \
- _ret; \
+#define my_syscall0(num) \
+({ \
+ long _ret = (num); \
+ __asm__ volatile ( \
+ "syscall\n" \
+ : "+a"(_ret) /* %rax */ \
+ : \
+ : "rcx", "r11", "memory", "cc" \
+ ); \
+ _ret; \
})
-#define my_syscall1(num, arg1) \
-({ \
- long _ret; \
- register long _num __asm__("rax") = (num); \
- register long _arg1 __asm__("rdi") = (long)(arg1); \
- \
- __asm__ volatile ( \
- "syscall\n" \
- : "=a"(_ret) \
- : "r"(_arg1), \
- "0"(_num) \
- : "rcx", "r11", "memory", "cc" \
- ); \
- _ret; \
+#define my_syscall1(num, arg1) \
+({ \
+ long _ret = (num); \
+ __asm__ volatile ( \
+ "syscall\n" \
+ : "+a"(_ret) /* %rax */ \
+ : "D"(arg1) /* %rdi */ \
+ : "rcx", "r11", "memory", "cc" \
+ ); \
+ _ret; \
})
-#define my_syscall2(num, arg1, arg2) \
-({ \
- long _ret; \
- register long _num __asm__("rax") = (num); \
- register long _arg1 __asm__("rdi") = (long)(arg1); \
- register long _arg2 __asm__("rsi") = (long)(arg2); \
- \
- __asm__ volatile ( \
- "syscall\n" \
- : "=a"(_ret) \
- : "r"(_arg1), "r"(_arg2), \
- "0"(_num) \
- : "rcx", "r11", "memory", "cc" \
- ); \
- _ret; \
+#define my_syscall2(num, arg1, arg2) \
+({ \
+ long _ret = (num); \
+ __asm__ volatile ( \
+ "syscall\n" \
+ : "+a"(_ret) /* %rax */ \
+ : "D"(arg1), /* %rdi */ \
+ "S"(arg2) /* %rsi */ \
+ : "rcx", "r11", "memory", "cc" \
+ ); \
+ _ret; \
})
-#define my_syscall3(num, arg1, arg2, arg3) \
-({ \
- long _ret; \
- register long _num __asm__("rax") = (num); \
- register long _arg1 __asm__("rdi") = (long)(arg1); \
- register long _arg2 __asm__("rsi") = (long)(arg2); \
- register long _arg3 __asm__("rdx") = (long)(arg3); \
- \
- __asm__ volatile ( \
- "syscall\n" \
- : "=a"(_ret) \
- : "r"(_arg1), "r"(_arg2), "r"(_arg3), \
- "0"(_num) \
- : "rcx", "r11", "memory", "cc" \
- ); \
- _ret; \
+#define my_syscall3(num, arg1, arg2, arg3) \
+({ \
+ long _ret = (num); \
+ __asm__ volatile ( \
+ "syscall\n" \
+ : "+a"(_ret) /* %rax */ \
+ : "D"(arg1), /* %rdi */ \
+ "S"(arg2), /* %rsi */ \
+ "d"(arg3) /* %rdx */ \
+ : "rcx", "r11", "memory", "cc" \
+ ); \
+ _ret; \
})
-#define my_syscall4(num, arg1, arg2, arg3, arg4) \
-({ \
- long _ret; \
- register long _num __asm__("rax") = (num); \
- register long _arg1 __asm__("rdi") = (long)(arg1); \
- register long _arg2 __asm__("rsi") = (long)(arg2); \
- register long _arg3 __asm__("rdx") = (long)(arg3); \
- register long _arg4 __asm__("r10") = (long)(arg4); \
- \
- __asm__ volatile ( \
- "syscall\n" \
- : "=a"(_ret) \
- : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), \
- "0"(_num) \
- : "rcx", "r11", "memory", "cc" \
- ); \
- _ret; \
+#define my_syscall4(num, arg1, arg2, arg3, arg4) \
+({ \
+ long _ret = (num); \
+ register long _arg4 __asm__("r10") = (long)(arg4); \
+ __asm__ volatile ( \
+ "syscall\n" \
+ : "+a"(_ret) /* %rax */ \
+ : "D"(arg1), /* %rdi */ \
+ "S"(arg2), /* %rsi */ \
+ "d"(arg3), /* %rdx */ \
+ "r"(_arg4) /* %r10 */ \
+ : "rcx", "r11", "memory", "cc" \
+ ); \
+ _ret; \
})
-#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
-({ \
- long _ret; \
- register long _num __asm__("rax") = (num); \
- register long _arg1 __asm__("rdi") = (long)(arg1); \
- register long _arg2 __asm__("rsi") = (long)(arg2); \
- register long _arg3 __asm__("rdx") = (long)(arg3); \
- register long _arg4 __asm__("r10") = (long)(arg4); \
- register long _arg5 __asm__("r8") = (long)(arg5); \
- \
- __asm__ volatile ( \
- "syscall\n" \
- : "=a"(_ret) \
- : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
- "0"(_num) \
- : "rcx", "r11", "memory", "cc" \
- ); \
- _ret; \
+#define my_syscall5(num, arg1, arg2, arg3, arg4, arg5) \
+({ \
+ long _ret = (num); \
+ register long _arg4 __asm__("r10") = (long)(arg4); \
+ register long _arg5 __asm__("r8") = (long)(arg5); \
+ __asm__ volatile ( \
+ "syscall\n" \
+ : "+a"(_ret) /* %rax */ \
+ : "D"(arg1), /* %rdi */ \
+ "S"(arg2), /* %rsi */ \
+ "d"(arg3), /* %rdx */ \
+ "r"(_arg4), /* %r10 */ \
+ "r"(_arg5) /* %r8 */ \
+ : "rcx", "r11", "memory", "cc" \
+ ); \
+ _ret; \
})
-#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
-({ \
- long _ret; \
- register long _num __asm__("rax") = (num); \
- register long _arg1 __asm__("rdi") = (long)(arg1); \
- register long _arg2 __asm__("rsi") = (long)(arg2); \
- register long _arg3 __asm__("rdx") = (long)(arg3); \
- register long _arg4 __asm__("r10") = (long)(arg4); \
- register long _arg5 __asm__("r8") = (long)(arg5); \
- register long _arg6 __asm__("r9") = (long)(arg6); \
- \
- __asm__ volatile ( \
- "syscall\n" \
- : "=a"(_ret) \
- : "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5), \
- "r"(_arg6), "0"(_num) \
- : "rcx", "r11", "memory", "cc" \
- ); \
- _ret; \
+#define my_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6) \
+({ \
+ long _ret = (num); \
+ register long _arg4 __asm__("r10") = (long)(arg4); \
+ register long _arg5 __asm__("r8") = (long)(arg5); \
+ register long _arg6 __asm__("r9") = (long)(arg6); \
+ __asm__ volatile ( \
+ "syscall\n" \
+ : "+a"(_ret) /* %rax */ \
+ : "D"(arg1), /* %rdi */ \
+ "S"(arg2), /* %rsi */ \
+ "d"(arg3), /* %rdx */ \
+ "r"(_arg4), /* %r10 */ \
+ "r"(_arg5), /* %r8 */ \
+ "r"(_arg6) /* %r9 */ \
+ : "rcx", "r11", "memory", "cc" \
+ ); \
+ _ret; \
})
/* startup code */
--
Ammar Faizi