* [PATCH] powerpc: Avoid link stack corruption in {add_}reloc_offset
@ 2021-08-20 5:16 Christophe Leroy
0 siblings, 0 replies; only message in thread
From: Christophe Leroy @ 2021-08-20 5:16 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman
Cc: linux-kernel, linuxppc-dev
reloc_offset() / add_reloc_offset() used bl;mflr to get code
position.
Use bcl 20,31,+4 instead of bl in order to preserve link stack.
See commit c974809a26a1 ("powerpc/vdso: Avoid link stack corruption
in __get_datapage()") for details.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
arch/powerpc/kernel/misc.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/misc.S b/arch/powerpc/kernel/misc.S
index 5be96feccb55..acd557637a3c 100644
--- a/arch/powerpc/kernel/misc.S
+++ b/arch/powerpc/kernel/misc.S
@@ -29,7 +29,7 @@ _GLOBAL(reloc_offset)
li r3, 0
_GLOBAL(add_reloc_offset)
mflr r0
- bl 1f
+ bcl 20,31,1f
1: mflr r5
PPC_LL r4,(2f-1b)(r5)
subf r5,r4,r5
--
2.25.0
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