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d03e8b226c
If we get a SIGPROF on a non-Go thread, and the program has not called runtime.SetCgoTraceback so we have no way to collect a stack trace, then record a profile that is just the PC where the signal occurred. That will at least point the user to the right area. Retrieving the PC from the sigctxt in a signal handler on a non-G thread required marking a number of trivial sigctxt methods as nosplit, and, for extra safety, nowritebarrierrec. The test shows that the existing test CgoPprofThread test does not test the stack trace, just the profile signal. Leaving that for later. Change-Id: I8f8f3ff09ac099fc9d9df94b5a9d210ffc20c4ab Reviewed-on: https://go-review.googlesource.com/30252 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
64 lines
2.3 KiB
Go
64 lines
2.3 KiB
Go
// Copyright 2013 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package runtime
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import "unsafe"
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type sigctxt struct {
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info *siginfo
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ctxt unsafe.Pointer
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}
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//go:nosplit
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//go:nowritebarrierrec
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func (c *sigctxt) regs() *regs32 { return &(*ucontext)(c.ctxt).uc_mcontext.ss }
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func (c *sigctxt) eax() uint32 { return c.regs().eax }
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func (c *sigctxt) ebx() uint32 { return c.regs().ebx }
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func (c *sigctxt) ecx() uint32 { return c.regs().ecx }
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func (c *sigctxt) edx() uint32 { return c.regs().edx }
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func (c *sigctxt) edi() uint32 { return c.regs().edi }
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func (c *sigctxt) esi() uint32 { return c.regs().esi }
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func (c *sigctxt) ebp() uint32 { return c.regs().ebp }
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func (c *sigctxt) esp() uint32 { return c.regs().esp }
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//go:nosplit
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//go:nowritebarrierrec
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func (c *sigctxt) eip() uint32 { return c.regs().eip }
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func (c *sigctxt) eflags() uint32 { return c.regs().eflags }
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func (c *sigctxt) cs() uint32 { return c.regs().cs }
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func (c *sigctxt) fs() uint32 { return c.regs().fs }
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func (c *sigctxt) gs() uint32 { return c.regs().gs }
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func (c *sigctxt) sigcode() uint32 { return uint32(c.info.si_code) }
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func (c *sigctxt) sigaddr() uint32 { return c.info.si_addr }
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func (c *sigctxt) set_eip(x uint32) { c.regs().eip = x }
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func (c *sigctxt) set_esp(x uint32) { c.regs().esp = x }
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func (c *sigctxt) set_sigcode(x uint32) { c.info.si_code = int32(x) }
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func (c *sigctxt) set_sigaddr(x uint32) { c.info.si_addr = x }
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func (c *sigctxt) fixsigcode(sig uint32) {
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switch sig {
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case _SIGTRAP:
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// OS X sets c.sigcode() == TRAP_BRKPT unconditionally for all SIGTRAPs,
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// leaving no way to distinguish a breakpoint-induced SIGTRAP
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// from an asynchronous signal SIGTRAP.
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// They all look breakpoint-induced by default.
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// Try looking at the code to see if it's a breakpoint.
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// The assumption is that we're very unlikely to get an
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// asynchronous SIGTRAP at just the moment that the
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// PC started to point at unmapped memory.
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pc := uintptr(c.eip())
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// OS X will leave the pc just after the INT 3 instruction.
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// INT 3 is usually 1 byte, but there is a 2-byte form.
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code := (*[2]byte)(unsafe.Pointer(pc - 2))
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if code[1] != 0xCC && (code[0] != 0xCD || code[1] != 3) {
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// SIGTRAP on something other than INT 3.
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c.set_sigcode(_SI_USER)
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}
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}
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}
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