linux-kernel - [PATCH AUTOSEL 4.4 14/14] scripts/decodecode: fix trapping instruction formatting

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Message-Id: <20200514185625.21753-14-sashal@kernel.org>
Date:   Thu, 14 May 2020 14:56:25 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Ivan Delalande <colona@...sta.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Borislav Petkov <bp@...e.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 4.4 14/14] scripts/decodecode: fix trapping instruction formatting

From: Ivan Delalande <colona@...sta.com>

[ Upstream commit e08df079b23e2e982df15aa340bfbaf50f297504 ]

If the trapping instruction contains a ':', for a memory access through
segment registers for example, the sed substitution will insert the '*'
marker in the middle of the instruction instead of the line address:

	2b:   65 48 0f c7 0f          cmpxchg16b %gs:*(%rdi)          <-- trapping instruction

I started to think I had forgotten some quirk of the assembly syntax
before noticing that it was actually coming from the script.  Fix it to
add the address marker at the right place for these instructions:

	28:   49 8b 06                mov    (%r14),%rax
	2b:*  65 48 0f c7 0f          cmpxchg16b %gs:(%rdi)           <-- trapping instruction
	30:   0f 94 c0                sete   %al

Fixes: 18ff44b189e2 ("scripts/decodecode: make faulting insn ptr more robust")
Signed-off-by: Ivan Delalande <colona@...sta.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Reviewed-by: Borislav Petkov <bp@...e.de>
Link: http://lkml.kernel.org/r/20200419223653.GA31248@visor
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 scripts/decodecode | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/scripts/decodecode b/scripts/decodecode
index d8824f37acce9..aae7a035242b2 100755
--- a/scripts/decodecode
+++ b/scripts/decodecode
@@ -98,7 +98,7 @@ faultlinenum=$(( $(wc -l $T.oo  | cut -d" " -f1) - \
 faultline=`cat $T.dis | head -1 | cut -d":" -f2-`
 faultline=`echo "$faultline" | sed -e 's/\[/\\\[/g; s/\]/\\\]/g'`
 
-cat $T.oo | sed -e "${faultlinenum}s/^\(.*:\)\(.*\)/\1\*\2\t\t<-- trapping instruction/"
+cat $T.oo | sed -e "${faultlinenum}s/^\([^:]*:\)\(.*\)/\1\*\2\t\t<-- trapping instruction/"
 echo
 cat $T.aa
 cleanup
-- 
2.20.1