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authorPeter Zijlstra <peterz@infradead.org>2022-03-08 18:30:56 +0300
committerPeter Zijlstra <peterz@infradead.org>2022-03-15 12:32:47 +0300
commited53a0d971926e484d86cce617ec02a7ee85c3fe (patch)
tree1423484f3912113c56c0b77fa5b0397113040828 /arch/um
parent89bc853eae4ad125030ef99f207ba76c2f00a26e (diff)
downloadlinux-ed53a0d971926e484d86cce617ec02a7ee85c3fe.tar.xz
x86/alternative: Use .ibt_endbr_seal to seal indirect calls
Objtool's --ibt option generates .ibt_endbr_seal which lists superfluous ENDBR instructions. That is those instructions for which the function is never indirectly called. Overwrite these ENDBR instructions with a NOP4 such that these function can never be indirect called, reducing the number of viable ENDBR targets in the kernel. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lore.kernel.org/r/20220308154319.822545231@infradead.org
Diffstat (limited to 'arch/um')
-rw-r--r--arch/um/kernel/um_arch.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/um/kernel/um_arch.c b/arch/um/kernel/um_arch.c
index abceeabe29b9..0760e24f2eba 100644
--- a/arch/um/kernel/um_arch.c
+++ b/arch/um/kernel/um_arch.c
@@ -424,6 +424,10 @@ void __init check_bugs(void)
os_check_bugs();
}
+void apply_ibt_endbr(s32 *start, s32 *end)
+{
+}
+
void apply_retpolines(s32 *start, s32 *end)
{
}