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From: Andrii Nakryiko <andrii@kernel.org>
To: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
	martin.lau@kernel.org
Cc: andrii@kernel.org, kernel-team@meta.com,
	kernel test robot <lkp@intel.com>
Subject: [PATCH bpf-next] bpf: handle CONFIG_SMP=n configuration in x86 BPF JIT
Date: Wed,  3 Apr 2024 20:47:26 -0700	[thread overview]
Message-ID: <20240404034726.2766740-1-andrii@kernel.org> (raw)

On non-SMP systems, there is no "per-CPU" data, it's just global data.
So in such case just don't do this_cpu_off-based per-CPU address adjustment.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202404040951.d4CUx5S6-lkp@intel.com/
Fixes: 7bdbf7446305 ("bpf: add special internal-only MOV instruction to resolve per-CPU addrs")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
---
 arch/x86/net/bpf_jit_comp.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index af89dd117dce..964e8154da66 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -1383,15 +1383,14 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, u8 *rw_image
 				EMIT3(0x0F, 0x44, add_2reg(0xC0, AUX_REG, dst_reg));
 				break;
 			} else if (insn_is_mov_percpu_addr(insn)) {
-				u32 off = (u32)(unsigned long)&this_cpu_off;
-
 				/* mov <dst>, <src> (if necessary) */
 				EMIT_mov(dst_reg, src_reg);
-
+#ifdef CONFIG_SMP
 				/* add <dst>, gs:[<off>] */
 				EMIT2(0x65, add_1mod(0x48, dst_reg));
 				EMIT3(0x03, add_1reg(0x04, dst_reg), 0x25);
-				EMIT(off, 4);
+				EMIT((u32)(unsigned long)&this_cpu_off, 4);
+#endif
 				break;
 			}
 			fallthrough;
-- 
2.43.0


             reply	other threads:[~2024-04-04  3:47 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-04  3:47 Andrii Nakryiko [this message]
2024-04-04  4:40 ` [PATCH bpf-next] bpf: handle CONFIG_SMP=n configuration in x86 BPF JIT patchwork-bot+netdevbpf

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