From ddc7c4f936c7a90781072f10dbaa122007e939d0 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Tue, 16 Jul 2019 20:49:02 -0400 Subject: clean up mips64/n32 syscall asm constraints ever since inline syscalls were added for (o32) mips in commit 328810d32524e4928fec50b57e37e1bf330b2e40, the asm has nonsensically loaded the syscall number, rather than taking $2 as an input constraint to let the compiler load it. commit cfc09b1ecf0c6981494fd73dffe234416f66af10 improved on this somewhat by allowing a constant syscall number to propagate into an immediate, but missed that the whole operation made no sense. now, only $4, $5, $6, $8, and $9 are potential input-only registers. $2 is always input and output, and $7 is both when it's an argument, otherwise output-only. previously, $7 was treated as an input (with a "1" constraint matching its output position) even when it was not an input, which was arguably undefined behavior (asm input from indeterminate value). this is corrected. --- arch/mips64/syscall_arch.h | 55 +++++++++++++++++++++++----------------------- 1 file changed, 28 insertions(+), 27 deletions(-) (limited to 'arch/mips64') diff --git a/arch/mips64/syscall_arch.h b/arch/mips64/syscall_arch.h index a653c31c..1e720c7d 100644 --- a/arch/mips64/syscall_arch.h +++ b/arch/mips64/syscall_arch.h @@ -53,10 +53,11 @@ static void __stat_fix(struct kernel_stat *kst, struct stat *st) static inline long __syscall0(long n) { register long r7 __asm__("$7"); - register long r2 __asm__("$2"); + register long r2 __asm__("$2") = n; __asm__ __volatile__ ( - "daddu $2,$0,%2 ; syscall" - : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7) + "syscall" + : "+&r"(r2), "=r"(r7) + : : SYSCALL_CLOBBERLIST); return r7 ? -r2 : r2; } @@ -65,11 +66,11 @@ static inline long __syscall1(long n, long a) { register long r4 __asm__("$4") = a; register long r7 __asm__("$7"); - register long r2 __asm__("$2"); + register long r2 __asm__("$2") = n; __asm__ __volatile__ ( - "daddu $2,$0,%2 ; syscall" - : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7), - "r"(r4) + "syscall" + : "+&r"(r2), "=r"(r7) + : "r"(r4) : SYSCALL_CLOBBERLIST); return r7 ? -r2 : r2; } @@ -81,15 +82,15 @@ static inline long __syscall2(long n, long a, long b) register long r4 __asm__("$4") = a; register long r5 __asm__("$5") = b; register long r7 __asm__("$7"); - register long r2 __asm__("$2"); + register long r2 __asm__("$2") = n; if (n == SYS_stat || n == SYS_fstat || n == SYS_lstat) r5 = (long) &kst; __asm__ __volatile__ ( - "daddu $2,$0,%2 ; syscall" - : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7), - "r"(r4), "r"(r5) + "syscall" + : "+&r"(r2), "=r"(r7) + : "r"(r4), "r"(r5) : SYSCALL_CLOBBERLIST); if (r7) return -r2; @@ -109,15 +110,15 @@ static inline long __syscall3(long n, long a, long b, long c) register long r5 __asm__("$5") = b; register long r6 __asm__("$6") = c; register long r7 __asm__("$7"); - register long r2 __asm__("$2"); + register long r2 __asm__("$2") = n; if (n == SYS_stat || n == SYS_fstat || n == SYS_lstat) r5 = (long) &kst; __asm__ __volatile__ ( - "daddu $2,$0,%2 ; syscall" - : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7), - "r"(r4), "r"(r5), "r"(r6) + "syscall" + : "+&r"(r2), "=r"(r7) + : "r"(r4), "r"(r5), "r"(r6) : SYSCALL_CLOBBERLIST); if (r7) return -r2; @@ -137,7 +138,7 @@ static inline long __syscall4(long n, long a, long b, long c, long d) register long r5 __asm__("$5") = b; register long r6 __asm__("$6") = c; register long r7 __asm__("$7") = d; - register long r2 __asm__("$2"); + register long r2 __asm__("$2") = n; if (n == SYS_stat || n == SYS_fstat || n == SYS_lstat) r5 = (long) &kst; @@ -145,9 +146,9 @@ static inline long __syscall4(long n, long a, long b, long c, long d) r6 = (long) &kst; __asm__ __volatile__ ( - "daddu $2,$0,%2 ; syscall" - : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7), - "r"(r4), "r"(r5), "r"(r6) + "syscall" + : "+&r"(r2), "+r"(r7) + : "r"(r4), "r"(r5), "r"(r6) : SYSCALL_CLOBBERLIST); if (r7) return -r2; @@ -170,7 +171,7 @@ static inline long __syscall5(long n, long a, long b, long c, long d, long e) register long r6 __asm__("$6") = c; register long r7 __asm__("$7") = d; register long r8 __asm__("$8") = e; - register long r2 __asm__("$2"); + register long r2 __asm__("$2") = n; if (n == SYS_stat || n == SYS_fstat || n == SYS_lstat) r5 = (long) &kst; @@ -178,9 +179,9 @@ static inline long __syscall5(long n, long a, long b, long c, long d, long e) r6 = (long) &kst; __asm__ __volatile__ ( - "daddu $2,$0,%2 ; syscall" - : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7), - "r"(r4), "r"(r5), "r"(r6), "r"(r8) + "syscall" + : "+&r"(r2), "+r"(r7) + : "r"(r4), "r"(r5), "r"(r6), "r"(r8) : SYSCALL_CLOBBERLIST); if (r7) return -r2; @@ -204,7 +205,7 @@ static inline long __syscall6(long n, long a, long b, long c, long d, long e, lo register long r7 __asm__("$7") = d; register long r8 __asm__("$8") = e; register long r9 __asm__("$9") = f; - register long r2 __asm__("$2"); + register long r2 __asm__("$2") = n; if (n == SYS_stat || n == SYS_fstat || n == SYS_lstat) r5 = (long) &kst; @@ -212,9 +213,9 @@ static inline long __syscall6(long n, long a, long b, long c, long d, long e, lo r6 = (long) &kst; __asm__ __volatile__ ( - "daddu $2,$0,%2 ; syscall" - : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7), - "r"(r4), "r"(r5), "r"(r6), "r"(r8), "r"(r9) + "syscall" + : "+&r"(r2), "+r"(r7) + : "r"(r4), "r"(r5), "r"(r6), "r"(r8), "r"(r9) : SYSCALL_CLOBBERLIST); if (r7) return -r2; -- cgit v1.2.1