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authorMichael Ellerman <mpe@ellerman.id.au>2018-04-16 15:25:19 +0200
committerMichael Ellerman <mpe@ellerman.id.au>2018-04-16 16:37:48 +0200
commitb8858581febb050688e276b956796bc4a78299ed (patch)
tree987871ef037230c31ade099c076e903a060fac93 /arch/powerpc
parentLinux 4.17-rc1 (diff)
downloadlinux-b8858581febb050688e276b956796bc4a78299ed.tar.xz
linux-b8858581febb050688e276b956796bc4a78299ed.zip
powerpc/lib: Fix off-by-one in alternate feature patching
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>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/lib/feature-fixups.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index 35f80ab7cbd8..288fe4f0db4e 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;