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LoongArch: BPF: Fix check condition to call lu32id in move_imm() 

commit 4eece7e6de upstream.

As the code comment says, the initial aim is to reduce one instruction
in some corner cases, if bit[51:31] is all 0 or all 1, no need to call
lu32id. That is to say, it should call lu32id only if bit[51:31] is not
all 0 and not all 1. The current code always call lu32id, the result is
right but the logic is unexpected and wrong, fix it.

Cc: stable@vger.kernel.org # 6.1
Fixes: 5dc615520c ("LoongArch: Add BPF JIT support")
Reported-by: Colin King (gmail) <colin.i.king@gmail.com>
Closes: https://lore.kernel.org/all/bcf97046-e336-712a-ac68-7fd194f2953e@gmail.com/
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Tiezhu Yang 2023-07-28 10:30:42 +08:00 committed by Greg Kroah-Hartman
parent 024ed3b9b8
commit 8a5e0c1f71
1 changed files with 1 additions and 1 deletions
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2
arch/loongarch/net/bpf_jit.h
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@ -148,7 +148,7 @@ static inline void move_imm(struct jit_ctx *ctx, enum loongarch_gpr rd, long imm
* no need to call lu32id to do a new filled operation.
*/
imm_51_31 = (imm >> 31) & 0x1fffff;
if (imm_51_31 != 0 || imm_51_31 != 0x1fffff) {
if (imm_51_31 != 0 && imm_51_31 != 0x1fffff) {
/* lu32id rd, imm_51_32 */
imm_51_32 = (imm >> 32) & 0xfffff;
emit_insn(ctx, lu32id, rd, imm_51_32);