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.

diff --git a/arch/mips64/syscall_arch.h b/arch/mips64/syscall_arch.h
index a653c31c6ed54f2b8bfd40cc4e924efeddc9c6c1..1e720c7d801b3d049b2d9b9c36eab35b301cb9e8 100644 (file)
--- 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;

diff --git a/arch/mipsn32/syscall_arch.h b/arch/mipsn32/syscall_arch.h
index 90823a99ce5dfced5c39158bb8989cd60b55fd1e..894c033d84f6c8ce1fae97f972fc0984eecb7868 100644 (file)
--- a/arch/mipsn32/syscall_arch.h
+++ b/arch/mipsn32/syscall_arch.h
@@ -22,10 +22,11 @@ static inline void __stat_fix(long p)
 static inline long __syscall0(long n)
 {
        register long r7 __asm__("$7");
-       register long r2 __asm__("$2");
+       register long r2 __asm__("$2") = n;
        __asm__ __volatile__ (
-               "addu $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;
 }
@@ -34,11 +35,11 @@ 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__ (
-               "addu $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;
 }
@@ -48,11 +49,11 @@ 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;
        __asm__ __volatile__ (
-               "addu $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;
        long ret = r2;
@@ -66,11 +67,11 @@ 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;
        __asm__ __volatile__ (
-               "addu $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;
        long ret = r2;
@@ -84,11 +85,11 @@ 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;
        __asm__ __volatile__ (
-               "addu $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;
        long ret = r2;
@@ -104,11 +105,11 @@ 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;
        __asm__ __volatile__ (
-               "addu $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 (n == SYS_stat || n == SYS_fstat || n == SYS_lstat) __stat_fix(b);
        if (n == SYS_newfstatat) __stat_fix(c);
@@ -123,11 +124,11 @@ 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;
        __asm__ __volatile__ (
-               "addu $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 (n == SYS_stat || n == SYS_fstat || n == SYS_lstat) __stat_fix(b);
        if (n == SYS_newfstatat) __stat_fix(c);