From 7833deb95e05bec146414b3a2feb24f025ca27c0 Mon Sep 17 00:00:00 2001 From: Hari Bathini Date: Tue, 22 Apr 2025 13:56:09 +0530 Subject: powerpc/bpf: fix JIT code size calculation of bpf trampoline commit 59ba025948be2a92e8bc9ae1cbdaf197660bd508 upstream. arch_bpf_trampoline_size() provides JIT size of the BPF trampoline before the buffer for JIT'ing it is allocated. The total number of instructions emitted for BPF trampoline JIT code depends on where the final image is located. So, the size arrived at with the dummy pass in arch_bpf_trampoline_size() can vary from the actual size needed in arch_prepare_bpf_trampoline(). When the instructions accounted in arch_bpf_trampoline_size() is less than the number of instructions emitted during the actual JIT compile of the trampoline, the below warning is produced: WARNING: CPU: 8 PID: 204190 at arch/powerpc/net/bpf_jit_comp.c:981 __arch_prepare_bpf_trampoline.isra.0+0xd2c/0xdcc which is: /* Make sure the trampoline generation logic doesn't overflow */ if (image && WARN_ON_ONCE(&image[ctx->idx] > (u32 *)rw_image_end - BPF_INSN_SAFETY)) { So, during the dummy pass, instead of providing some arbitrary image location, account for maximum possible instructions if and when there is a dependency with image location for JIT'ing. Fixes: d243b62b7bd3 ("powerpc64/bpf: Add support for bpf trampolines") Reported-by: Venkat Rao Bagalkote Closes: https://lore.kernel.org/all/6168bfc8-659f-4b5a-a6fb-90a916dde3b3@linux.ibm.com/ Cc: stable@vger.kernel.org # v6.13+ Acked-by: Naveen N Rao (AMD) Tested-by: Venkat Rao Bagalkote Signed-off-by: Hari Bathini Signed-off-by: Madhavan Srinivasan Link: https://patch.msgid.link/20250422082609.949301-1-hbathini@linux.ibm.com Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/net/bpf_jit_comp32.c | 6 ------ 1 file changed, 6 deletions(-) (limited to 'arch/powerpc/net/bpf_jit_comp32.c') diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index c4db278dae36..0aace304dfe1 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c @@ -313,7 +313,6 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code u64 func_addr; u32 true_cond; u32 tmp_idx; - int j; if (i && (BPF_CLASS(code) == BPF_ALU64 || BPF_CLASS(code) == BPF_ALU) && (BPF_CLASS(prevcode) == BPF_ALU64 || BPF_CLASS(prevcode) == BPF_ALU) && @@ -1099,13 +1098,8 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code * 16 byte instruction that uses two 'struct bpf_insn' */ case BPF_LD | BPF_IMM | BPF_DW: /* dst = (u64) imm */ - tmp_idx = ctx->idx; PPC_LI32(dst_reg_h, (u32)insn[i + 1].imm); PPC_LI32(dst_reg, (u32)insn[i].imm); - /* padding to allow full 4 instructions for later patching */ - if (!image) - for (j = ctx->idx - tmp_idx; j < 4; j++) - EMIT(PPC_RAW_NOP()); /* Adjust for two bpf instructions */ addrs[++i] = ctx->idx * 4; break; -- cgit v1.2.3