[PULL 2/8] linux-user/sh4: fix vdso CFA for rt_sigreturn frames

[Helge Deller <deller@kernel.org>]

From: Matt Turner <mattst88@gmail.com>

The unwinder looks up a return address as IP - 1 (hence the nop before
sigreturn_region_start). For a frame returning to __kernel_rt_sigreturn
that is the last byte of __kernel_sigreturn, which still has the
sigreturn CFA, so the rt_sigreturn frame is unwound with the wrong
sigcontext offset. _Unwind_Backtrace() from an SA_SIGINFO handler stops
after three frames.

Add a nop after .cfi_def_cfa_offset, as linux-user/i386/vdso.S does.

Fixes: 975bd51a88 ("linux-user/sh4: add VDSO support for sh4 and sh4eb")
Cc: qemu-stable@nongnu.org
Signed-off-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Helge Deller <deller@gmx.de>
Signed-off-by: Helge Deller <deller@gmx.de>
---
 linux-user/sh4/vdso-be.so | Bin 2720 -> 2720 bytes
 linux-user/sh4/vdso-le.so | Bin 2720 -> 2720 bytes
 linux-user/sh4/vdso.S     |   3 ++-
 3 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/linux-user/sh4/vdso-be.so b/linux-user/sh4/vdso-be.so
index bc1fb37e1089b7aa5612da0039e24193b156b3d8..df9fa22efab46bffbb9957af078199639998ea43 100755
GIT binary patch
delta 94
zcmZ1=x<GWo6OqVuQt#KSJ9B!^(@jmb3bB#wuObyE{&>##V)FyW-As%sljpE_2{CX^
vW<4yRzzu^8YbPf%icjWeeZcr*@(0#@#ut+l*u2^Nd@N1<oHuV|d(R92IA0@3

delta 94
zcmZ1=x<GWo6Op!OLQF3#0+d8#l(nNCM8CN5&G7ofAI}+|ZGOPGn~70r@*EZ~p~<X=
u1r)epkYOzY=j232@yYzG4;a5q{=k~g_-t|ln>SlhXr*UW(&mk9@0kI)8X|`P

diff --git a/linux-user/sh4/vdso-le.so b/linux-user/sh4/vdso-le.so
index c1ff560cc165413d7b07aa873225bd92afb8569e..decd674202260f045b646b318ebb0b6daf416651 100755
GIT binary patch
delta 93
zcmZ1=x<GWo6Olh5saKn)T)*7)W8rK!`{(^j`F=Z0{PBeG#pb(=yO|hOCeLK?735@K
uoh)#eTLA{wPEKSLoy^1ffbqxVx2*Y$FDA#b`LUHn_<IEVZ{EoEo*4j_?<GY5

delta 93
zcmZ1=x<GWo6Op|ikGEYj60C8&_)xA>#wX*~i%pXz{&>RpZ1Y{l-As&1lV`H{3bIZX
uILxg8gKHT$CnqwBPUc~K!1!(QTh@HWXOm;u{Md{<Esc#+H*aKn&kO)kh$G_w

diff --git a/linux-user/sh4/vdso.S b/linux-user/sh4/vdso.S
index 1faa665774..290eb498ae 100644
--- a/linux-user/sh4/vdso.S
+++ b/linux-user/sh4/vdso.S
@@ -141,8 +141,9 @@ __kernel_sigreturn:
 	sigreturn_tramp __NR_sigreturn
 endf __kernel_sigreturn
 
-	/* Update CFA base for the rt_sigreturn frame layout. */
+	/* rt_sigreturn frame layout; nop for the same reason as above. */
 	.cfi_def_cfa_offset	RT_SIGFRAME_SC_OFFSET
+	nop
 
 __kernel_rt_sigreturn:
 	sigreturn_tramp __NR_rt_sigreturn
-- 
2.54.0