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runtime: mark morestack_noctxt SPWRITE on LR architectures

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On LR architectures, morestack (and morestack_noctxt) are called
with a special calling convention, where the caller doesn't save
LR on stack but passes it as a register, which morestack will save
to g.sched.lr. The stack unwinder currently doesn't understand it,
and would fail to unwind from it. morestack already writes SP (as
it switches stack), but morestack_noctxt (which tailcalls
morestack) doesn't. If a profiling signal lands right in
morestack_noctxt, the unwinder will try to unwind the stack and
go off, and possibly crash.

Marking morestack_noctxt SPWRITE stops the unwinding.

Ideally we could teach the unwinder about the special calling
convention, or change the calling convention to be less special
(so the unwinder doesn't need to fetch a register from the signal
context). This is a stop-gap solution, to stop the unwinder from
crashing.

Fixes #54332.

Change-Id: I75295f2e27ddcf05f1ea0b541aedcb9000ae7576
Reviewed-on: https://go-review.googlesource.com/c/go/+/425396
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
This commit is contained in:
Cherry Mui 2022-08-24 18:33:21 -04:00
parent d4ff25ac69
commit e4be2ac79f
7 changed files with 51 additions and 2 deletions
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7
src/runtime/asm_arm.s
View File

@ -387,6 +387,13 @@ TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0
RET
TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0
// Force SPWRITE. This function doesn't actually write SP,
// but it is called with a special calling convention where
// the caller doesn't save LR on stack but passes it as a
// register (R3), and the unwinder currently doesn't understand.
// Make it SPWRITE to stop unwinding. (See issue 54332)
MOVW R13, R13
MOVW $0, R7
B runtime·morestack(SB)

7
src/runtime/asm_arm64.s
View File

@ -320,6 +320,13 @@ TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0
UNDEF
TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0
// Force SPWRITE. This function doesn't actually write SP,
// but it is called with a special calling convention where
// the caller doesn't save LR on stack but passes it as a
// register (R3), and the unwinder currently doesn't understand.
// Make it SPWRITE to stop unwinding. (See issue 54332)
MOVD RSP, RSP
MOVW $0, R26
B runtime·morestack(SB)

7
src/runtime/asm_mips64x.s
View File

@ -258,6 +258,13 @@ TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0
UNDEF
TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0
// Force SPWRITE. This function doesn't actually write SP,
// but it is called with a special calling convention where
// the caller doesn't save LR on stack but passes it as a
// register (R3), and the unwinder currently doesn't understand.
// Make it SPWRITE to stop unwinding. (See issue 54332)
MOVV R29, R29
MOVV R0, REGCTXT
JMP runtime·morestack(SB)

7
src/runtime/asm_mipsx.s
View File

@ -257,6 +257,13 @@ TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0
UNDEF
TEXT runtime·morestack_noctxt(SB),NOSPLIT,$0-0
// Force SPWRITE. This function doesn't actually write SP,
// but it is called with a special calling convention where
// the caller doesn't save LR on stack but passes it as a
// register (R3), and the unwinder currently doesn't understand.
// Make it SPWRITE to stop unwinding. (See issue 54332)
MOVW R29, R29
MOVW R0, REGCTXT
JMP runtime·morestack(SB)

7
src/runtime/asm_ppc64x.s
View File

@ -334,6 +334,13 @@ TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0
UNDEF
TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0
// Force SPWRITE. This function doesn't actually write SP,
// but it is called with a special calling convention where
// the caller doesn't save LR on stack but passes it as a
// register (R5), and the unwinder currently doesn't understand.
// Make it SPWRITE to stop unwinding. (See issue 54332)
MOVD R1, R1
MOVD R0, R11
BR runtime·morestack(SB)

11
src/runtime/asm_riscv64.s
View File

@ -158,8 +158,8 @@ TEXT runtime·getcallerpc(SB),NOSPLIT|NOFRAME,$0-8
*/
// Called during function prolog when more stack is needed.
// Caller has already loaded:
// R1: framesize, R2: argsize, R3: LR
// Called with return address (i.e. caller's PC) in X5 (aka T0),
// and the LR register contains the caller's LR.
//
// The traceback routines see morestack on a g0 as being
// the top of a stack (for example, morestack calling newstack
@ -209,6 +209,13 @@ TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0
// func morestack_noctxt()
TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0
// Force SPWRITE. This function doesn't actually write SP,
// but it is called with a special calling convention where
// the caller doesn't save LR on stack but passes it as a
// register, and the unwinder currently doesn't understand.
// Make it SPWRITE to stop unwinding. (See issue 54332)
MOV X2, X2
MOV ZERO, CTXT
JMP runtime·morestack(SB)

7
src/runtime/asm_s390x.s
View File

@ -346,6 +346,13 @@ TEXT runtime·morestack(SB),NOSPLIT|NOFRAME,$0-0
UNDEF
TEXT runtime·morestack_noctxt(SB),NOSPLIT|NOFRAME,$0-0
// Force SPWRITE. This function doesn't actually write SP,
// but it is called with a special calling convention where
// the caller doesn't save LR on stack but passes it as a
// register (R5), and the unwinder currently doesn't understand.
// Make it SPWRITE to stop unwinding. (See issue 54332)
MOVD R15, R15
MOVD $0, R12
BR runtime·morestack(SB)