From: dankis01 <dankis01@arm.com>
To: <linux-arm-kernel@lists.infradead.org>,
<Vincenzo.Frascino@arm.com>, <mark.rutland@arm.com>
Cc: Tamas Zsoldos <tamas.zsoldos@arm.com>, Daniel Kiss <daniel.kiss@arm.com>
Subject: [PATCH] arm64: vdso: Fix CFI info in sigreturn.
Date: Fri, 15 May 2020 18:20:20 +0200 [thread overview]
Message-ID: <20200515162020.78169-1-daniel.kiss@arm.com> (raw)
When the signal handler is called the registers set up as the return address
points to the __kernel_rt_sigreturn. The NOP here is the placeholder of the
branch and link instruction that "calls" the signal handler. In case of a
return address the unwinder identifies the location of the caller because
in some cases the return address might not exist. Since the .cfi_startproc
is after the NOP, it won't be associated with any location and the
unwinder will stop walking.
This change corrects the generated EHFrames only.
Signed-off-by: Daniel Kiss <daniel.kiss@arm.com>
Signed-off-by: Tamas Zsoldos <tamas.zsoldos@arm.com>
---
arch/arm64/kernel/vdso/sigreturn.S | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/vdso/sigreturn.S b/arch/arm64/kernel/vdso/sigreturn.S
index 12324863d5c2..5d50ee92faa4 100644
--- a/arch/arm64/kernel/vdso/sigreturn.S
+++ b/arch/arm64/kernel/vdso/sigreturn.S
@@ -13,13 +13,13 @@
.text
- nop
-SYM_FUNC_START(__kernel_rt_sigreturn)
.cfi_startproc
.cfi_signal_frame
.cfi_def_cfa x29, 0
.cfi_offset x29, 0 * 8
.cfi_offset x30, 1 * 8
+ nop /* placeholder for bl signalhandler */
+SYM_FUNC_START(__kernel_rt_sigreturn)
mov x8, #__NR_rt_sigreturn
svc #0
.cfi_endproc
--
2.17.1
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next reply other threads:[~2020-05-15 16:20 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-15 16:20 dankis01 [this message]
2020-05-18 15:59 ` [PATCH] arm64: vdso: Fix CFI info in sigreturn Dave Martin
2020-05-18 17:00 ` Daniel Kiss
2020-05-19 9:29 ` Dave Martin
2020-05-19 11:34 ` Will Deacon
[not found] <30E488CA-46FF-4927-A07F-8CE11263B92E@arm.com>
[not found] ` <CF896434-E995-438C-88F8-86CCFE24C5A2@arm.com>
2020-05-08 9:52 ` Daniel Kiss
2020-05-15 15:23 ` Mark Rutland
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