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[compiler-rt] Mark $t* as clobbered for Linux/LoongArch syscalls

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Linux/LoongArch doesn't preserve temporary registers across syscalls,
so we have to explicitly mark them as clobbered to avoid trashing local variables.

Reviewed By: xry111, xen0n, tangyouling, SixWeining

Differential Revision: https://reviews.llvm.org/D137396
This commit is contained in:
XingLi 2022-11-11 21:22:45 +08:00 committed by Weining Lu
parent 2f1c942f80
commit 1e2c20fc13
1 changed files with 10 additions and 6 deletions
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16
compiler-rt/lib/sanitizer_common/sanitizer_syscall_linux_loongarch64.inc
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@ -14,14 +14,18 @@
// About local register variables:
// https://gcc.gnu.org/onlinedocs/gcc/Local-Register-Variables.html#Local-Register-Variables
//
// Kernel ABI...
// syscall number is passed in a7
// (http://man7.org/linux/man-pages/man2/syscall.2.html) results are return in
// a0 and a1 (http://man7.org/linux/man-pages/man2/syscall.2.html) arguments
// are passed in: a0-a7 (confirmed by inspecting glibc sources).
// Kernel ABI:
// https://lore.kernel.org/loongarch/1f353678-3398-e30b-1c87-6edb278f74db@xen0n.name/T/#m1613bc86c2d7bf5f6da92bd62984302bfd699a2f
// syscall number is placed in a7
// parameters, if present, are placed in a0-a6
// upon return:
// the return value is placed in a0
// t0-t8 should be considered clobbered
// all other registers are preserved
#define SYSCALL(name) __NR_##name
#define INTERNAL_SYSCALL_CLOBBERS "memory"
#define INTERNAL_SYSCALL_CLOBBERS \
"memory", "$t0", "$t1", "$t2", "$t3", "$t4", "$t5", "$t6", "$t7", "$t8"
static uptr __internal_syscall(u64 nr) {
register u64 a7 asm("$a7") = nr;