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.h | 20 +++++++++++++++++--- 1 file changed, 17 insertions(+), 3 deletions(-) (limited to 'arch/powerpc/net/bpf_jit.h') diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index 6beacaec63d3..4c26912c2e3c 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h @@ -51,8 +51,16 @@ EMIT(PPC_INST_BRANCH_COND | (((cond) & 0x3ff) << 16) | (offset & 0xfffc)); \ } while (0) -/* Sign-extended 32-bit immediate load */ +/* + * Sign-extended 32-bit immediate load + * + * If this is a dummy pass (!image), account for + * maximum possible instructions. + */ #define PPC_LI32(d, i) do { \ + if (!image) \ + ctx->idx += 2; \ + else { \ if ((int)(uintptr_t)(i) >= -32768 && \ (int)(uintptr_t)(i) < 32768) \ EMIT(PPC_RAW_LI(d, i)); \ @@ -60,10 +68,15 @@ EMIT(PPC_RAW_LIS(d, IMM_H(i))); \ if (IMM_L(i)) \ EMIT(PPC_RAW_ORI(d, d, IMM_L(i))); \ - } } while(0) + } \ + } } while (0) #ifdef CONFIG_PPC64 +/* If dummy pass (!image), account for maximum possible instructions */ #define PPC_LI64(d, i) do { \ + if (!image) \ + ctx->idx += 5; \ + else { \ if ((long)(i) >= -2147483648 && \ (long)(i) < 2147483648) \ PPC_LI32(d, i); \ @@ -84,7 +97,8 @@ if ((uintptr_t)(i) & 0x000000000000ffffULL) \ EMIT(PPC_RAW_ORI(d, d, (uintptr_t)(i) & \ 0xffff)); \ - } } while (0) + } \ + } } while (0) #define PPC_LI_ADDR PPC_LI64 #ifndef CONFIG_PPC_KERNEL_PCREL -- cgit v1.2.3