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authorMichael Ellerman <mpe@ellerman.id.au>2018-04-16 23:25:19 +1000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-04-24 09:34:17 +0200
commit22578e220a870d7e677839eab207185faec3144a (patch)
parent73de98fb50b077934776563c97b75d6f764a2066 (diff)
powerpc/lib: Fix off-by-one in alternate feature patching
commit b8858581febb050688e276b956796bc4a78299ed upstream. When we patch an alternate feature section, we have to adjust any relative branches that branch out of the alternate section. But currently we have a bug if we have a branch that points to past the last instruction of the alternate section, eg: FTR_SECTION_ELSE 1: b 2f or 6,6,6 2: ALT_FTR_SECTION_END(...) nop This will result in a relative branch at 1 with a target that equals the end of the alternate section. That branch does not need adjusting when it's moved to the non-else location. Currently we do adjust it, resulting in a branch that goes off into the link-time location of the else section, which is junk. The fix is to not patch branches that have a target == end of the alternate section. Fixes: d20fe50a7b3c ("KVM: PPC: Book3S HV: Branch inside feature section") Fixes: 9b1a735de64c ("powerpc: Add logic to patch alternative feature sections") Cc: stable@vger.kernel.org # v2.6.27+ Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index e86bfa111f3c..46c8338a61bc 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -55,7 +55,7 @@ static int patch_alt_instruction(unsigned int *src, unsigned int *dest,
unsigned int *target = (unsigned int *)branch_target(src);
/* Branch within the section doesn't need translating */
- if (target < alt_start || target >= alt_end) {
+ if (target < alt_start || target > alt_end) {
instr = translate_branch(dest, src);
if (!instr)
return 1;