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authorArcher Yan <ayan@wavecomp.com>2019-03-08 03:29:19 +0000
committerPaul Burton <paul.burton@mips.com>2019-03-11 11:11:11 -0700
commit47c25036b60f27b86ab44b66a8861bcf81cde39b (patch)
treea8f62bb0230208c170bfc3bad53506aa82a266e6
parent3f0a53bc6482fb09770982a8447981260ea258dc (diff)
MIPS: Fix kernel crash for R6 in jump label branch function
Insert Branch instruction instead of NOP to make sure assembler don't patch code in forbidden slot. In jump label function, it might be possible to patch Control Transfer Instructions(CTIs) into forbidden slot, which will generate Reserved Instruction exception in MIPS release 6. Signed-off-by: Archer Yan <ayan@wavecomp.com> Reviewed-by: Paul Burton <paul.burton@mips.com> [paul.burton@mips.com: - Add MIPS prefix to subject. - Mark for stable from v4.0, which introduced r6 support, onwards.] Signed-off-by: Paul Burton <paul.burton@mips.com> Cc: linux-mips@vger.kernel.org Cc: stable@vger.kernel.org # v4.0+
-rw-r--r--arch/mips/include/asm/jump_label.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
index e77672539e8e..e4456e450f94 100644
--- a/arch/mips/include/asm/jump_label.h
+++ b/arch/mips/include/asm/jump_label.h
@@ -21,15 +21,15 @@
#endif
#ifdef CONFIG_CPU_MICROMIPS
-#define NOP_INSN "nop32"
+#define B_INSN "b32"
#else
-#define NOP_INSN "nop"
+#define B_INSN "b"
#endif
static __always_inline bool arch_static_branch(struct static_key *key, bool branch)
{
- asm_volatile_goto("1:\t" NOP_INSN "\n\t"
- "nop\n\t"
+ asm_volatile_goto("1:\t" B_INSN " 2f\n\t"
+ "2:\tnop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
WORD_INSN " 1b, %l[l_yes], %0\n\t"
".popsection\n\t"