diff options
Diffstat (limited to 'src/runtime/signal_darwin_amd64.go')
| -rw-r--r-- | src/runtime/signal_darwin_amd64.go | 96 |
1 files changed, 96 insertions, 0 deletions
diff --git a/src/runtime/signal_darwin_amd64.go b/src/runtime/signal_darwin_amd64.go new file mode 100644 index 0000000..20544d8 --- /dev/null +++ b/src/runtime/signal_darwin_amd64.go @@ -0,0 +1,96 @@ +// Copyright 2013 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +package runtime + +import "unsafe" + +type sigctxt struct { + info *siginfo + ctxt unsafe.Pointer +} + +//go:nosplit +//go:nowritebarrierrec +func (c *sigctxt) regs() *regs64 { return &(*ucontext)(c.ctxt).uc_mcontext.ss } + +func (c *sigctxt) rax() uint64 { return c.regs().rax } +func (c *sigctxt) rbx() uint64 { return c.regs().rbx } +func (c *sigctxt) rcx() uint64 { return c.regs().rcx } +func (c *sigctxt) rdx() uint64 { return c.regs().rdx } +func (c *sigctxt) rdi() uint64 { return c.regs().rdi } +func (c *sigctxt) rsi() uint64 { return c.regs().rsi } +func (c *sigctxt) rbp() uint64 { return c.regs().rbp } +func (c *sigctxt) rsp() uint64 { return c.regs().rsp } +func (c *sigctxt) r8() uint64 { return c.regs().r8 } +func (c *sigctxt) r9() uint64 { return c.regs().r9 } +func (c *sigctxt) r10() uint64 { return c.regs().r10 } +func (c *sigctxt) r11() uint64 { return c.regs().r11 } +func (c *sigctxt) r12() uint64 { return c.regs().r12 } +func (c *sigctxt) r13() uint64 { return c.regs().r13 } +func (c *sigctxt) r14() uint64 { return c.regs().r14 } +func (c *sigctxt) r15() uint64 { return c.regs().r15 } + +//go:nosplit +//go:nowritebarrierrec +func (c *sigctxt) rip() uint64 { return c.regs().rip } + +func (c *sigctxt) rflags() uint64 { return c.regs().rflags } +func (c *sigctxt) cs() uint64 { return c.regs().cs } +func (c *sigctxt) fs() uint64 { return c.regs().fs } +func (c *sigctxt) gs() uint64 { return c.regs().gs } +func (c *sigctxt) sigcode() uint64 { return uint64(c.info.si_code) } +func (c *sigctxt) sigaddr() uint64 { return c.info.si_addr } + +func (c *sigctxt) set_rip(x uint64) { c.regs().rip = x } +func (c *sigctxt) set_rsp(x uint64) { c.regs().rsp = x } +func (c *sigctxt) set_sigcode(x uint64) { c.info.si_code = int32(x) } +func (c *sigctxt) set_sigaddr(x uint64) { c.info.si_addr = x } + +//go:nosplit +func (c *sigctxt) fixsigcode(sig uint32) { + switch sig { + case _SIGTRAP: + // OS X sets c.sigcode() == TRAP_BRKPT unconditionally for all SIGTRAPs, + // leaving no way to distinguish a breakpoint-induced SIGTRAP + // from an asynchronous signal SIGTRAP. + // They all look breakpoint-induced by default. + // Try looking at the code to see if it's a breakpoint. + // The assumption is that we're very unlikely to get an + // asynchronous SIGTRAP at just the moment that the + // PC started to point at unmapped memory. + pc := uintptr(c.rip()) + // OS X will leave the pc just after the INT 3 instruction. + // INT 3 is usually 1 byte, but there is a 2-byte form. + code := (*[2]byte)(unsafe.Pointer(pc - 2)) + if code[1] != 0xCC && (code[0] != 0xCD || code[1] != 3) { + // SIGTRAP on something other than INT 3. + c.set_sigcode(_SI_USER) + } + + case _SIGSEGV: + // x86-64 has 48-bit virtual addresses. The top 16 bits must echo bit 47. + // The hardware delivers a different kind of fault for a malformed address + // than it does for an attempt to access a valid but unmapped address. + // OS X 10.9.2 mishandles the malformed address case, making it look like + // a user-generated signal (like someone ran kill -SEGV ourpid). + // We pass user-generated signals to os/signal, or else ignore them. + // Doing that here - and returning to the faulting code - results in an + // infinite loop. It appears the best we can do is rewrite what the kernel + // delivers into something more like the truth. The address used below + // has very little chance of being the one that caused the fault, but it is + // malformed, it is clearly not a real pointer, and if it does get printed + // in real life, people will probably search for it and find this code. + // There are no Google hits for b01dfacedebac1e or 0xb01dfacedebac1e + // as I type this comment. + // + // Note: if this code is removed, please consider + // enabling TestSignalForwardingGo for darwin-amd64 in + // misc/cgo/testcarchive/carchive_test.go. + if c.sigcode() == _SI_USER { + c.set_sigcode(_SI_USER + 1) + c.set_sigaddr(0xb01dfacedebac1e) + } + } +} |