From: Abhishek Dubey <[email protected]> Ensure the dummy trampoline address field present between the OOL stub and the long branch stub is 4/8-byte aligned, for memory compatibility when content loaded to a register.
Reported-by: Hari Bathini <[email protected]> Fixes: d243b62b7bd3 ("powerpc64/bpf: Add support for bpf trampolines") Cc: [email protected] Signed-off-by: Abhishek Dubey <[email protected]> Signed-off-by: Saket Kumar Bhaskar <[email protected]> Tested-by: Yeswanth Krishna Tellakula <[email protected]> --- arch/powerpc/net/bpf_jit.h | 7 +++--- arch/powerpc/net/bpf_jit_comp.c | 38 ++++++++++++++++++++++++++----- arch/powerpc/net/bpf_jit_comp32.c | 7 +++--- arch/powerpc/net/bpf_jit_comp64.c | 7 +++--- 4 files changed, 44 insertions(+), 15 deletions(-) diff --git a/arch/powerpc/net/bpf_jit.h b/arch/powerpc/net/bpf_jit.h index 6d58df361648..4da8bde92e1e 100644 --- a/arch/powerpc/net/bpf_jit.h +++ b/arch/powerpc/net/bpf_jit.h @@ -227,10 +227,11 @@ int bpf_jit_emit_func_call_rel(u32 *image, u32 *fimage, struct codegen_context * int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct codegen_context *ctx, u32 *addrs, int pass, bool extra_pass); void bpf_jit_build_prologue(u32 *image, struct codegen_context *ctx); -void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx); -void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx); +void bpf_jit_build_epilogue(u32 *image, u32 *fimage, struct codegen_context *ctx); +void bpf_jit_build_fentry_stubs(u32 *image, u32 *fimage, struct codegen_context *ctx); void bpf_jit_realloc_regs(struct codegen_context *ctx); -int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr); +int bpf_jit_emit_exit_insn(u32 *image, u32 *fimage, struct codegen_context *ctx, int tmp_reg, + long exit_addr); void prepare_for_fsession_fentry(u32 *image, struct codegen_context *ctx, int cookie_cnt, int cookie_off, int retval_off); void store_func_meta(u32 *image, struct codegen_context *ctx, u64 func_meta, int func_meta_off); diff --git a/arch/powerpc/net/bpf_jit_comp.c b/arch/powerpc/net/bpf_jit_comp.c index 11981d2270a9..8ca36a933c7a 100644 --- a/arch/powerpc/net/bpf_jit_comp.c +++ b/arch/powerpc/net/bpf_jit_comp.c @@ -49,11 +49,35 @@ asm ( " .popsection ;" ); -void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx) +void bpf_jit_build_fentry_stubs(u32 *image, u32 *fimage, struct codegen_context *ctx) { int ool_stub_idx, long_branch_stub_idx; + int ool_stub_sz; /* + * Align the mis-aligned dummy_tramp_addr field in the fimage. + * The alignment NOP must appear before OOL stub, to make + * ool_stub_idx & long_branch_stub_idx constant from end. + * + * The fimage can be non 8-byte aligned, so final alignment depends + * on start of fimage and the stub's instruction count offset. The + * OOL stub size is 4 instructions (with CONFIG_PPC_FTRACE_OUT_OF_LINE) + * or 3 instructions (without) before dummy_tramp_addr. + * + * Emit a NOP here if address is not SZL aligned. + * + * In pass=0 when image==NULL, conservatively account for space + * required to accommodate alignment NOP. In case final pass skips + * emitting alignment NOP, the image buffer have 4 spare bytes and + * jited_len signifies correct program size. + */ + + ool_stub_sz = IS_ENABLED(CONFIG_PPC_FTRACE_OUT_OF_LINE) ? 16 : 12; + if (!image || !IS_ALIGNED((unsigned long)fimage + ctx->idx*4 + ool_stub_sz, SZL)) + EMIT(PPC_RAW_NOP()); + + /* + * nop // optional, for alignment of dummy_tramp_addr * Out-of-line stub: * mflr r0 * [b|bl] tramp @@ -70,7 +94,7 @@ void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx) /* * Long branch stub: - * .long <dummy_tramp_addr> + * .long <dummy_tramp_addr> // 8-byte aligned * mflr r11 * bcl 20,31,$+4 * mflr r12 @@ -81,6 +105,7 @@ void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx) */ if (image) *((unsigned long *)&image[ctx->idx]) = (unsigned long)dummy_tramp; + ctx->idx += SZL / 4; long_branch_stub_idx = ctx->idx; EMIT(PPC_RAW_MFLR(_R11)); @@ -97,7 +122,8 @@ void bpf_jit_build_fentry_stubs(u32 *image, struct codegen_context *ctx) } } -int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, long exit_addr) +int bpf_jit_emit_exit_insn(u32 *image, u32 *fimage, struct codegen_context *ctx, + int tmp_reg, long exit_addr) { if (exit_addr && is_offset_in_branch_range(exit_addr - (long)(ctx->idx * 4))) { PPC_JMP(exit_addr); @@ -106,7 +132,7 @@ int bpf_jit_emit_exit_insn(u32 *image, struct codegen_context *ctx, int tmp_reg, PPC_JMP(ctx->alt_exit_addr); } else { ctx->alt_exit_addr = ctx->idx * 4; - bpf_jit_build_epilogue(image, ctx); + bpf_jit_build_epilogue(image, fimage, ctx); } return 0; @@ -286,7 +312,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_verifier_env *env, struct bpf_pr */ bpf_jit_build_prologue(NULL, &cgctx); addrs[fp->len] = cgctx.idx * 4; - bpf_jit_build_epilogue(NULL, &cgctx); + bpf_jit_build_epilogue(NULL, NULL, &cgctx); fixup_len = fp->aux->num_exentries * BPF_FIXUP_LEN * 4; extable_len = fp->aux->num_exentries * sizeof(struct exception_table_entry); @@ -322,7 +348,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_verifier_env *env, struct bpf_pr goto out_err; } addrs[fp->len] = cgctx.idx * 4; - bpf_jit_build_epilogue(code_base, &cgctx); + bpf_jit_build_epilogue(code_base, fcode_base, &cgctx); proglen = cgctx.idx * 4; diff --git a/arch/powerpc/net/bpf_jit_comp32.c b/arch/powerpc/net/bpf_jit_comp32.c index bfdc50740da8..f5b9441cf46a 100644 --- a/arch/powerpc/net/bpf_jit_comp32.c +++ b/arch/powerpc/net/bpf_jit_comp32.c @@ -229,7 +229,7 @@ static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx } -void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) +void bpf_jit_build_epilogue(u32 *image, u32 *fimage, struct codegen_context *ctx) { EMIT(PPC_RAW_MR(_R3, bpf_to_ppc(BPF_REG_0))); @@ -237,7 +237,7 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) EMIT(PPC_RAW_BLR()); - bpf_jit_build_fentry_stubs(image, ctx); + bpf_jit_build_fentry_stubs(image, fimage, ctx); } /* Relative offset needs to be calculated based on final image location */ @@ -1149,7 +1149,8 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code * we'll just fall through to the epilogue. */ if (i != flen - 1) { - ret = bpf_jit_emit_exit_insn(image, ctx, _R0, exit_addr); + ret = bpf_jit_emit_exit_insn(image, fimage, + ctx, _R0, exit_addr); if (ret) return ret; } diff --git a/arch/powerpc/net/bpf_jit_comp64.c b/arch/powerpc/net/bpf_jit_comp64.c index 59302cabc466..e80312171aa7 100644 --- a/arch/powerpc/net/bpf_jit_comp64.c +++ b/arch/powerpc/net/bpf_jit_comp64.c @@ -398,7 +398,7 @@ static void bpf_jit_emit_common_epilogue(u32 *image, struct codegen_context *ctx } } -void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) +void bpf_jit_build_epilogue(u32 *image, u32 *fimage, struct codegen_context *ctx) { bpf_jit_emit_common_epilogue(image, ctx); @@ -407,7 +407,7 @@ void bpf_jit_build_epilogue(u32 *image, struct codegen_context *ctx) EMIT(PPC_RAW_BLR()); - bpf_jit_build_fentry_stubs(image, ctx); + bpf_jit_build_fentry_stubs(image, fimage, ctx); } /* @@ -1737,7 +1737,8 @@ int bpf_jit_build_body(struct bpf_prog *fp, u32 *image, u32 *fimage, struct code * we'll just fall through to the epilogue. */ if (i != flen - 1) { - ret = bpf_jit_emit_exit_insn(image, ctx, tmp1_reg, exit_addr); + ret = bpf_jit_emit_exit_insn(image, fimage, ctx, + tmp1_reg, exit_addr); if (ret) return ret; } -- 2.55.0
