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authorWill Deacon <will.deacon@arm.com>2015-08-04 18:52:09 +0100
committerWill Deacon <will.deacon@arm.com>2015-08-04 18:52:09 +0100
commit04b8637be92f284409651088f3856f4290a931d8 (patch)
treeaee6f9d734c0893139664f38d6438e3897dd568b
parent7f08a414f29e7daea661d03231998625257ed3f1 (diff)
downloadlinux-04b8637be92f284409651088f3856f4290a931d8.tar.bz2
arm64: alternatives: ensure secondary CPUs execute ISB after patching
In order to guarantee that the patched instruction stream is visible to a CPU, that CPU must execute an isb instruction after any related cache maintenance has completed. The instruction patching routines in kernel/insn.c get this right for things like jump labels and ftrace, but the alternatives patching omits it entirely leaving secondary cores in a potential limbo between the old and the new code. This patch adds an isb following the secondary polling loop in the altenatives patching. Signed-off-by: Will Deacon <will.deacon@arm.com>
-rw-r--r--arch/arm64/kernel/alternative.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
index fa1d575ab2c2..ab9db0e9818c 100644
--- a/arch/arm64/kernel/alternative.c
+++ b/arch/arm64/kernel/alternative.c
@@ -132,6 +132,7 @@ static int __apply_alternatives_multi_stop(void *unused)
if (smp_processor_id()) {
while (!READ_ONCE(patched))
cpu_relax();
+ isb();
} else {
BUG_ON(patched);
__apply_alternatives(&region);