4.4-stable review patch. If anyone has any objections, please let me know.
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From: Archer Yan ayan@wavecomp.com
commit 47c25036b60f27b86ab44b66a8861bcf81cde39b upstream.
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+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- arch/mips/include/asm/jump_label.h | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
--- 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"