netdev - [PATCH] powerpc32: don't adjust unmoved stack pointer in csum_partial_copy

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Message-Id: <20201014230209.427011-1-Jason@zx2c4.com>
Date:   Thu, 15 Oct 2020 01:02:09 +0200
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     Al Viro <viro@...iv.linux.org.uk>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        netdev@...r.kernel.org
Cc:     "Jason A. Donenfeld" <Jason@...c4.com>
Subject: [PATCH] powerpc32: don't adjust unmoved stack pointer in csum_partial_copy_generic() epilogue

A recent change to the checksum code removed usage of some extra
arguments, alongside with storage on the stack for those, and the stack
pointer no longer needed to be adjusted in the function prologue. But, a
left over subtraction wasn't removed in the function epilogue, causing
the function to return with the stack pointer moved 16 bytes away from
where it should have. This corrupted local state and lead to weird
crashes. This commit simply removes the leftover instruction from the
epilogue.

Fixes: 70d65cd555c5 ("ppc: propagate the calling conventions change down to csum_partial_copy_generic()")
Cc: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 arch/powerpc/lib/checksum_32.S | 1 -
 1 file changed, 1 deletion(-)

diff --git a/arch/powerpc/lib/checksum_32.S b/arch/powerpc/lib/checksum_32.S
index ec5cd2dede35..27d9070617df 100644
--- a/arch/powerpc/lib/checksum_32.S
+++ b/arch/powerpc/lib/checksum_32.S
@@ -236,7 +236,6 @@ _GLOBAL(csum_partial_copy_generic)
 	slwi	r0,r0,8
 	adde	r12,r12,r0
 66:	addze	r3,r12
-	addi	r1,r1,16
 	beqlr+	cr7
 	rlwinm	r3,r3,8,0,31	/* odd destination address: rotate one byte */
 	blr
-- 
2.28.0