revert mips (32-bit, o32) syscall asm clean-up due to regressions

exactly revert commit 604f8d3d8b08ee4f548de193050ef93a7753c2e0 which
was wrong; it caused a major regression on Linux versions prior to
2.6.36. old kernels did not properly preserve r2 across syscall
restart, and instead restarted with the instruction right before
syscall, imposing a contract that the previous instruction must load
r2 from an immediate or a register (or memory) not clobbered by the
syscall.

diff --git a/arch/mips/syscall_arch.h b/arch/mips/syscall_arch.h
index f821e73fcc574ac47f70931e37a3e4a809c69917..a3812188fdf46cb2d6052e8222df104731309fab 100644 (file)
--- a/arch/mips/syscall_arch.h
+++ b/arch/mips/syscall_arch.h
@@ -18,11 +18,10 @@
 static inline long __syscall0(long n)
 {
        register long r7 __asm__("$7");
-       register long r2 __asm__("$2") = n;
+       register long r2 __asm__("$2");
        __asm__ __volatile__ (
-               "syscall"
-               : "+r"(r2), "=r"(r7)
-               :
+               "addu $2,$0,%2 ; syscall"
+               : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7)
                : SYSCALL_CLOBBERLIST, "$8", "$9", "$10");
        return r7 ? -r2 : r2;
 }
@@ -31,11 +30,11 @@ static inline long __syscall1(long n, long a)
 {
        register long r4 __asm__("$4") = a;
        register long r7 __asm__("$7");
-       register long r2 __asm__("$2") = n;
+       register long r2 __asm__("$2");
        __asm__ __volatile__ (
-               "syscall"
-               : "+r"(r2), "=r"(r7)
-               : "r"(r4)
+               "addu $2,$0,%2 ; syscall"
+               : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7),
+                 "r"(r4)
                : SYSCALL_CLOBBERLIST, "$8", "$9", "$10");
        return r7 ? -r2 : r2;
 }
@@ -45,11 +44,11 @@ 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") = n;
+       register long r2 __asm__("$2");
        __asm__ __volatile__ (
-               "syscall"
-               : "+r"(r2), "=r"(r7)
-               : "r"(r4), "r"(r5)
+               "addu $2,$0,%2 ; syscall"
+               : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7),
+                 "r"(r4), "r"(r5)
                : SYSCALL_CLOBBERLIST, "$8", "$9", "$10");
        return r7 ? -r2 : r2;
 }
@@ -60,11 +59,11 @@ 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") = n;
+       register long r2 __asm__("$2");
        __asm__ __volatile__ (
-               "syscall"
-               : "+r"(r2), "=r"(r7)
-               : "r"(r4), "r"(r5), "r"(r6)
+               "addu $2,$0,%2 ; syscall"
+               : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7),
+                 "r"(r4), "r"(r5), "r"(r6)
                : SYSCALL_CLOBBERLIST, "$8", "$9", "$10");
        return r7 ? -r2 : r2;
 }
@@ -75,11 +74,11 @@ 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") = n;
+       register long r2 __asm__("$2");
        __asm__ __volatile__ (
-               "syscall"
-               : "+r"(r2), "+r"(r7)
-               : "r"(r4), "r"(r5), "r"(r6)
+               "addu $2,$0,%2 ; syscall"
+               : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7),
+                 "r"(r4), "r"(r5), "r"(r6)
                : SYSCALL_CLOBBERLIST, "$8", "$9", "$10");
        return r7 ? -r2 : r2;
 }
@@ -91,13 +90,13 @@ 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") = n;
+       register long r2 __asm__("$2");
        __asm__ __volatile__ (
                "subu $sp,$sp,32 ; sw $8,16($sp) ; "
-               "syscall ;"
+               "addu $2,$0,%3 ; syscall ;"
                "addu $sp,$sp,32"
-               : "+r"(r2), "+r"(r7), "+r"(r8)
-               : "r"(r4), "r"(r5), "r"(r6)
+               : "=&r"(r2), "=r"(r7), "+r"(r8)
+               : "ir"(n), "0"(r2), "1"(r7), "r"(r4), "r"(r5), "r"(r6)
                : SYSCALL_CLOBBERLIST, "$9", "$10");
        return r7 ? -r2 : r2;
 }
@@ -110,13 +109,13 @@ 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") = n;
+       register long r2 __asm__("$2");
        __asm__ __volatile__ (
                "subu $sp,$sp,32 ; sw $8,16($sp) ; sw $9,20($sp) ; "
-               "syscall ;"
+               "addu $2,$0,%4 ; syscall ;"
                "addu $sp,$sp,32"
-               : "+r"(r2), "+r"(r7), "+r"(r8), "+r"(r9)
-               : "r"(r4), "r"(r5), "r"(r6)
+               : "=&r"(r2), "=r"(r7), "+r"(r8), "+r"(r9)
+               : "ir"(n), "0"(r2), "1"(r7), "r"(r4), "r"(r5), "r"(r6)
                : SYSCALL_CLOBBERLIST, "$10");
        return r7 ? -r2 : r2;
 }
@@ -130,13 +129,13 @@ static inline long __syscall7(long n, long a, long b, long c, long d, long e, lo
        register long r8 __asm__("$8") = e;
        register long r9 __asm__("$9") = f;
        register long r10 __asm__("$10") = g;
-       register long r2 __asm__("$2") = n;
+       register long r2 __asm__("$2");
        __asm__ __volatile__ (
                "subu $sp,$sp,32 ; sw $8,16($sp) ; sw $9,20($sp) ; sw $10,24($sp) ; "
-               "syscall ;"
+               "addu $2,$0,%5 ; syscall ;"
                "addu $sp,$sp,32"
-               : "+r"(r2), "+r"(r7), "+r"(r8), "+r"(r9), "+r"(r10)
-               : "r"(r4), "r"(r5), "r"(r6)
+               : "=&r"(r2), "=r"(r7), "+r"(r8), "+r"(r9), "+r"(r10)
+               : "ir"(n), "0"(r2), "1"(r7), "r"(r4), "r"(r5), "r"(r6)
                : SYSCALL_CLOBBERLIST);
        return r7 ? -r2 : r2;
 }