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

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exactly revert commit 604f8d3d8b 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.
This commit is contained in:
Rich Felker 2020-03-11 18:50:21 -04:00
parent 5053fd2644
commit 972b5fde9a
1 changed files with 31 additions and 32 deletions
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63
arch/mips/syscall_arch.h
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@ -18,11 +18,10 @@
static inline long __syscall0(long n) static inline long __syscall0(long n)
{ {
register long r7 __asm__("$7"); register long r7 __asm__("$7");
register long r2 __asm__("$2") = n; register long r2 __asm__("$2");
__asm__ __volatile__ ( __asm__ __volatile__ (
"syscall" "addu $2,$0,%2 ; syscall"
: "+r"(r2), "=r"(r7) : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7)
:
: SYSCALL_CLOBBERLIST, "$8", "$9", "$10"); : SYSCALL_CLOBBERLIST, "$8", "$9", "$10");
return r7 ? -r2 : r2; return r7 ? -r2 : r2;
} }
@ -31,11 +30,11 @@ static inline long __syscall1(long n, long a)
{ {
register long r4 __asm__("$4") = a; register long r4 __asm__("$4") = a;
register long r7 __asm__("$7"); register long r7 __asm__("$7");
register long r2 __asm__("$2") = n; register long r2 __asm__("$2");
__asm__ __volatile__ ( __asm__ __volatile__ (
"syscall" "addu $2,$0,%2 ; syscall"
: "+r"(r2), "=r"(r7) : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7),
: "r"(r4) "r"(r4)
: SYSCALL_CLOBBERLIST, "$8", "$9", "$10"); : SYSCALL_CLOBBERLIST, "$8", "$9", "$10");
return r7 ? -r2 : r2; 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 r4 __asm__("$4") = a;
register long r5 __asm__("$5") = b; register long r5 __asm__("$5") = b;
register long r7 __asm__("$7"); register long r7 __asm__("$7");
register long r2 __asm__("$2") = n; register long r2 __asm__("$2");
__asm__ __volatile__ ( __asm__ __volatile__ (
"syscall" "addu $2,$0,%2 ; syscall"
: "+r"(r2), "=r"(r7) : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7),
: "r"(r4), "r"(r5) "r"(r4), "r"(r5)
: SYSCALL_CLOBBERLIST, "$8", "$9", "$10"); : SYSCALL_CLOBBERLIST, "$8", "$9", "$10");
return r7 ? -r2 : r2; 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 r5 __asm__("$5") = b;
register long r6 __asm__("$6") = c; register long r6 __asm__("$6") = c;
register long r7 __asm__("$7"); register long r7 __asm__("$7");
register long r2 __asm__("$2") = n; register long r2 __asm__("$2");
__asm__ __volatile__ ( __asm__ __volatile__ (
"syscall" "addu $2,$0,%2 ; syscall"
: "+r"(r2), "=r"(r7) : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7),
: "r"(r4), "r"(r5), "r"(r6) "r"(r4), "r"(r5), "r"(r6)
: SYSCALL_CLOBBERLIST, "$8", "$9", "$10"); : SYSCALL_CLOBBERLIST, "$8", "$9", "$10");
return r7 ? -r2 : r2; 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 r5 __asm__("$5") = b;
register long r6 __asm__("$6") = c; register long r6 __asm__("$6") = c;
register long r7 __asm__("$7") = d; register long r7 __asm__("$7") = d;
register long r2 __asm__("$2") = n; register long r2 __asm__("$2");
__asm__ __volatile__ ( __asm__ __volatile__ (
"syscall" "addu $2,$0,%2 ; syscall"
: "+r"(r2), "+r"(r7) : "=&r"(r2), "=r"(r7) : "ir"(n), "0"(r2), "1"(r7),
: "r"(r4), "r"(r5), "r"(r6) "r"(r4), "r"(r5), "r"(r6)
: SYSCALL_CLOBBERLIST, "$8", "$9", "$10"); : SYSCALL_CLOBBERLIST, "$8", "$9", "$10");
return r7 ? -r2 : r2; 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 r6 __asm__("$6") = c;
register long r7 __asm__("$7") = d; register long r7 __asm__("$7") = d;
register long r8 __asm__("$8") = e; register long r8 __asm__("$8") = e;
register long r2 __asm__("$2") = n; register long r2 __asm__("$2");
__asm__ __volatile__ ( __asm__ __volatile__ (
"subu $sp,$sp,32 ; sw $8,16($sp) ; " "subu $sp,$sp,32 ; sw $8,16($sp) ; "
"syscall ;" "addu $2,$0,%3 ; syscall ;"
"addu $sp,$sp,32" "addu $sp,$sp,32"
: "+r"(r2), "+r"(r7), "+r"(r8) : "=&r"(r2), "=r"(r7), "+r"(r8)
: "r"(r4), "r"(r5), "r"(r6) : "ir"(n), "0"(r2), "1"(r7), "r"(r4), "r"(r5), "r"(r6)
: SYSCALL_CLOBBERLIST, "$9", "$10"); : SYSCALL_CLOBBERLIST, "$9", "$10");
return r7 ? -r2 : r2; 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 r7 __asm__("$7") = d;
register long r8 __asm__("$8") = e; register long r8 __asm__("$8") = e;
register long r9 __asm__("$9") = f; register long r9 __asm__("$9") = f;
register long r2 __asm__("$2") = n; register long r2 __asm__("$2");
__asm__ __volatile__ ( __asm__ __volatile__ (
"subu $sp,$sp,32 ; sw $8,16($sp) ; sw $9,20($sp) ; " "subu $sp,$sp,32 ; sw $8,16($sp) ; sw $9,20($sp) ; "
"syscall ;" "addu $2,$0,%4 ; syscall ;"
"addu $sp,$sp,32" "addu $sp,$sp,32"
: "+r"(r2), "+r"(r7), "+r"(r8), "+r"(r9) : "=&r"(r2), "=r"(r7), "+r"(r8), "+r"(r9)
: "r"(r4), "r"(r5), "r"(r6) : "ir"(n), "0"(r2), "1"(r7), "r"(r4), "r"(r5), "r"(r6)
: SYSCALL_CLOBBERLIST, "$10"); : SYSCALL_CLOBBERLIST, "$10");
return r7 ? -r2 : r2; 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 r8 __asm__("$8") = e;
register long r9 __asm__("$9") = f; register long r9 __asm__("$9") = f;
register long r10 __asm__("$10") = g; register long r10 __asm__("$10") = g;
register long r2 __asm__("$2") = n; register long r2 __asm__("$2");
__asm__ __volatile__ ( __asm__ __volatile__ (
"subu $sp,$sp,32 ; sw $8,16($sp) ; sw $9,20($sp) ; sw $10,24($sp) ; " "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" "addu $sp,$sp,32"
: "+r"(r2), "+r"(r7), "+r"(r8), "+r"(r9), "+r"(r10) : "=&r"(r2), "=r"(r7), "+r"(r8), "+r"(r9), "+r"(r10)
: "r"(r4), "r"(r5), "r"(r6) : "ir"(n), "0"(r2), "1"(r7), "r"(r4), "r"(r5), "r"(r6)
: SYSCALL_CLOBBERLIST); : SYSCALL_CLOBBERLIST);
return r7 ? -r2 : r2; return r7 ? -r2 : r2;
} }