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runtime: fix windows/arm externalthreadhandler

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Externalthreadhandler was not handling its own stack correctly.
It incorrectly referred to the saved LR slot (uninitialized, it turned out)
as holding the return value from the called function.

Externalthreadhandler is used to call two different functions:
profileloop1 and ctrlhandler1.
Profileloop1 does not return, so no harm done.
Ctrlhandler1 returns a boolean indicating whether the handler
took care of the control event (if true, no other handlers run).

It's hard to say exactly what uninitialized values are likely to
have been returned instead of ctrlhandler1's result, but it
probably wasn't helping matters.

Change-Id: Ia02f1c033df618cb82c2193b3a8241ed048a8b18
Reviewed-on: https://go-review.googlesource.com/c/go/+/288812
Trust: Russ Cox <rsc@golang.org>
Trust: Jason A. Donenfeld <Jason@zx2c4.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Russ Cox 2021-01-27 11:27:25 -05:00
parent 91cc484ea9
commit 5421c37a1d
1 changed files with 4 additions and 3 deletions
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7
src/runtime/sys_windows_arm.s
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@ -250,16 +250,17 @@ TEXT runtime·profileloop(SB),NOSPLIT|NOFRAME,$0
// +----------------+
// 12| argument (r0) |
//---+----------------+
// 8 | param1 |
// 8 | param1 | (also return value for called Go function)
// +----------------+
// 4 | param0 |
// +----------------+
// 0 | retval |
// 0 | slot for LR |
// +----------------+
//
TEXT runtime·externalthreadhandler(SB),NOSPLIT|NOFRAME|TOPFRAME,$0
MOVM.DB.W [R4-R11, R14], (R13) // push {r4-r11, lr}
SUB $(m__size + g__size + 20), R13 // space for locals
MOVW R14, 0(R13) // push LR again for anything unwinding the stack
MOVW R0, 12(R13)
MOVW R1, 16(R13)
@ -298,7 +299,7 @@ TEXT runtime·externalthreadhandler(SB),NOSPLIT|NOFRAME|TOPFRAME,$0
MOVW $0, g
BL runtime·save_g(SB)
MOVW 0(R13), R0 // load return value
MOVW 8(R13), R0 // load return value
ADD $(m__size + g__size + 20), R13 // free locals
MOVM.IA.W (R13), [R4-R11, R15] // pop {r4-r11, pc}