From: Jeremy Kerr <jk@ozlabs.org>
To: linuxppc-dev@lists.ozlabs.org
Subject: [PATCH 3/4] powerpc/boot: Fix stack corruption in epapr entry point
Date: Tue, 10 Feb 2015 20:15:10 +0800 [thread overview]
Message-ID: <1423570510.219047.52227904007.3.gpush@pablo> (raw)
In-Reply-To: <1423570510.218330.214724142596.1.gpush@pablo>
Currently, a 64-bit little-endian zImage.epapr won't boot in epapr mode,
as as we never return from platform_init.
Before entering C, we initialise our stack by setting r1 16 bytes below
the end of the _bss_stack:
stwu r0,-16(r1) /* establish a stack frame */
However, the called function will save the caller's lr in the caller's
frame's lr save area, at -16(r1) to -32(r1).
This means that writes to the fdt variable corrupt the saved link
register:
0000000020c06018 l O .bss 0000000000001000 _bss_stack
0000000020c07018 l O .bss 0000000000000008 fdt
This change allocates the minimum of 32 bytes for the base of the stack
instead.
Signed-off-by: Jeremy Kerr <jk@ozlabs.org>
---
arch/powerpc/boot/crt0.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/powerpc/boot/crt0.S b/arch/powerpc/boot/crt0.S
index 14de4f8..bf8eeee 100644
--- a/arch/powerpc/boot/crt0.S
+++ b/arch/powerpc/boot/crt0.S
@@ -218,7 +218,7 @@ p_base: mflr r10 /* r10 now points to runtime addr of p_base */
beq 6f
ld r1,0(r8)
li r0,0
- stdu r0,-16(r1) /* establish a stack frame */
+ stdu r0,-32(r1) /* establish a stack frame */
6:
#endif /* __powerpc64__ */
/* Call platform_init() */
next prev parent reply other threads:[~2015-02-10 12:15 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-10 12:15 [PATCH 1/4] powerpc/boot/fdt: Add little-endian support to libfdt wrappers Jeremy Kerr
2015-02-10 12:15 ` [PATCH 2/4] powerpc/boot/wrapper: use the pseries wrapper for zImage.epapr Jeremy Kerr
2015-02-11 2:12 ` Benjamin Herrenschmidt
2015-02-11 2:16 ` Jeremy Kerr
2015-02-11 2:20 ` Benjamin Herrenschmidt
2015-02-10 12:15 ` Jeremy Kerr [this message]
2015-02-11 2:11 ` [PATCH 3/4] powerpc/boot: Fix stack corruption in epapr entry point Benjamin Herrenschmidt
2015-02-10 12:15 ` [PATCH 4/4] powerpc/boot: don't clobber r6 and r7 in epapr boot Jeremy Kerr
2015-02-11 2:09 ` Benjamin Herrenschmidt
2015-02-11 4:27 ` Jeremy Kerr
2015-02-11 4:50 ` Benjamin Herrenschmidt
2015-02-11 2:11 ` [PATCH 1/4] powerpc/boot/fdt: Add little-endian support to libfdt wrappers Benjamin Herrenschmidt
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