diff options
Diffstat (limited to 'pkg/sentry/platform/safecopy/atomic_amd64.s')
| -rw-r--r-- | pkg/sentry/platform/safecopy/atomic_amd64.s | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/pkg/sentry/platform/safecopy/atomic_amd64.s b/pkg/sentry/platform/safecopy/atomic_amd64.s index 873ffa046..f90b4bfd1 100644 --- a/pkg/sentry/platform/safecopy/atomic_amd64.s +++ b/pkg/sentry/platform/safecopy/atomic_amd64.s @@ -106,3 +106,31 @@ TEXT ·compareAndSwapUint32(SB), NOSPLIT, $0-24 CMPXCHGL DX, 0(DI) MOVL AX, prev+16(FP) RET + +// handleLoadUint32Fault returns the value stored in DI. Control is transferred +// to it when LoadUint32 below receives SIGSEGV or SIGBUS, with the signal +// number stored in DI. +// +// It must have the same frame configuration as loadUint32 so that it can undo +// any potential call frame set up by the assembler. +TEXT handleLoadUint32Fault(SB), NOSPLIT, $0-16 + MOVL DI, sig+12(FP) + RET + +// loadUint32 atomically loads *addr and returns it. If a SIGSEGV or SIGBUS +// signal is received, the value returned is unspecified, and sig is the number +// of the signal that was received. +// +// Preconditions: addr must be aligned to a 4-byte boundary. +// +//func loadUint32(ptr unsafe.Pointer) (val uint32, sig int32) +TEXT ·loadUint32(SB), NOSPLIT, $0-16 + // Store 0 as the returned signal number. If we run to completion, + // this is the value the caller will see; if a signal is received, + // handleLoadUint32Fault will store a different value in this address. + MOVL $0, sig+12(FP) + + MOVQ addr+0(FP), AX + MOVL (AX), BX + MOVL BX, val+8(FP) + RET |