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AJvYcCXlj0i7697del9wtd9yteKGltTEn44PP/ziK/vLd0b9SzAIgIq/JbMikciA1yO/3Bm/5IbXo3/xIjE6Q+E0R0H+Dg72WUCLeIsop6n3 X-Gm-Message-State: AOJu0Yw6KjXAJT7wvjyoDImMBjDp0ZBuF1KBsn9ktv6ktc+5eGLTxXoF aI0El/GRXy/OD2eSDEufqGssRs1LNAaZIf8Sg7rv1jYNtFdNmxGSBWSdP9i3twc= X-Received: by 2002:a05:6358:7627:b0:17b:304f:b2b with SMTP id r39-20020a056358762700b0017b304f0b2bmr7270243rwg.26.1708940987303; Mon, 26 Feb 2024 01:49:47 -0800 (PST) Received: from C02CV19DML87.bytedance.net ([203.208.189.12]) by smtp.gmail.com with ESMTPSA id x19-20020a17090ab01300b002990d91d31dsm5934779pjq.15.2024.02.26.01.49.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Feb 2024 01:49:46 -0800 (PST) From: Rui Qi To: bp@alien8.de, mingo@redhat.com, tglx@linutronix.de, hpa@zytor.com, jpoimboe@redhat.com, peterz@infradead.org, mbenes@suse.cz, gregkh@linuxfoundation.org, stable@vger.kernel.org, alexandre.chartre@oracle.com Cc: x86@kernel.org, linux-kernel@vger.kernel.org, Rui Qi Subject: [PATCH 2/3] objtool: Add support for intra-function calls Date: Mon, 26 Feb 2024 17:49:24 +0800 Message-Id: <20240226094925.95835-3-qirui.001@bytedance.com> X-Mailer: git-send-email 2.39.2 (Apple Git-143) In-Reply-To: <20240226094925.95835-1-qirui.001@bytedance.com> References: <20240226094925.95835-1-qirui.001@bytedance.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Alexandre Chartre commit 8aa8eb2a8f5b3305a95f39957dd2b715fa668e21 upstream. Change objtool to support intra-function calls. On x86, an intra-function call is represented in objtool as a push onto the stack (of the return address), and a jump to the destination address. That way the stack information is correctly updated and the call flow is still accurate. Signed-off-by: Alexandre Chartre Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Miroslav Benes Acked-by: Josh Poimboeuf Link: https://lkml.kernel.org/r/20200414103618.12657-4-alexandre.chartre@oracle.com Signed-off-by: Rui Qi --- include/linux/frame.h | 11 ++++ .../Documentation/stack-validation.txt | 8 +++ tools/objtool/arch/x86/decode.c | 6 ++ tools/objtool/check.c | 62 +++++++++++++++++-- 4 files changed, 83 insertions(+), 4 deletions(-) diff --git a/include/linux/frame.h b/include/linux/frame.h index 02d3ca2d9598..303cda600e56 100644 --- a/include/linux/frame.h +++ b/include/linux/frame.h @@ -15,9 +15,20 @@ static void __used __section(.discard.func_stack_frame_non_standard) \ *__func_stack_frame_non_standard_##func = func +/* + * This macro indicates that the following intra-function call is valid. + * Any non-annotated intra-function call will cause objtool to issue a warning. + */ +#define ANNOTATE_INTRA_FUNCTION_CALL \ + 999: \ + .pushsection .discard.intra_function_calls; \ + .long 999b; \ + .popsection; + #else /* !CONFIG_STACK_VALIDATION */ #define STACK_FRAME_NON_STANDARD(func) +#define ANNOTATE_INTRA_FUNCTION_CALL #endif /* CONFIG_STACK_VALIDATION */ diff --git a/tools/objtool/Documentation/stack-validation.txt b/tools/objtool/Documentation/stack-validation.txt index de094670050b..ee26bb382b70 100644 --- a/tools/objtool/Documentation/stack-validation.txt +++ b/tools/objtool/Documentation/stack-validation.txt @@ -290,6 +290,14 @@ they mean, and suggestions for how to fix them. https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70646 +11. file.o: warning: unannotated intra-function call + + This warning means that a direct call is done to a destination which + is not at the beginning of a function. If this is a legit call, you + can remove this warning by putting the ANNOTATE_INTRA_FUNCTION_CALL + directive right before the call. + + If the error doesn't seem to make sense, it could be a bug in objtool. Feel free to ask the objtool maintainer for help. diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index a62e032863a8..c3ff62c085c8 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -437,6 +437,12 @@ int arch_decode_instruction(struct elf *elf, struct section *sec, case 0xe8: *type = INSN_CALL; + /* + * For the impact on the stack, a CALL behaves like + * a PUSH of an immediate value (the return address). + */ + op->src.type = OP_SRC_CONST; + op->dest.type = OP_DEST_PUSH; break; case 0xfc: diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 71a24fd46dbd..0fa414869f45 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -645,6 +645,7 @@ static int add_jump_destinations(struct objtool_file *file) return 0; } + /* * Find the destination instructions for all calls. */ @@ -666,10 +667,7 @@ static int add_call_destinations(struct objtool_file *file) dest_off); if (!insn->call_dest && !insn->ignore) { - WARN_FUNC("unsupported intra-function call", - insn->sec, insn->offset); - if (retpoline) - WARN("If this is a retpoline, please patch it in with alternatives and annotate it with ANNOTATE_NOSPEC_ALTERNATIVE."); + WARN_FUNC("unannotated intra-function call", insn->sec, insn->offset); return -1; } @@ -1291,6 +1289,58 @@ static int read_retpoline_hints(struct objtool_file *file) return 0; } + +static int read_intra_function_calls(struct objtool_file *file) +{ + struct instruction *insn; + struct section *sec; + struct rela *rela; + + sec = find_section_by_name(file->elf, ".rela.discard.intra_function_calls"); + if (!sec) + return 0; + + list_for_each_entry(rela, &sec->rela_list, list) { + unsigned long dest_off; + + if (rela->sym->type != STT_SECTION) { + WARN("unexpected relocation symbol type in %s", + sec->name); + return -1; + } + + insn = find_insn(file, rela->sym->sec, rela->addend); + if (!insn) { + WARN("bad .discard.intra_function_call entry"); + return -1; + } + + if (insn->type != INSN_CALL) { + WARN_FUNC("intra_function_call not a direct call", + insn->sec, insn->offset); + return -1; + } + + /* + * Treat intra-function CALLs as JMPs, but with a stack_op. + * See add_call_destinations(), which strips stack_ops from + * normal CALLs. + */ + insn->type = INSN_JUMP_UNCONDITIONAL; + + dest_off = insn->offset + insn->len + insn->immediate; + insn->jump_dest = find_insn(file, insn->sec, dest_off); + if (!insn->jump_dest) { + WARN_FUNC("can't find call dest at %s+0x%lx", + insn->sec, insn->offset, + insn->sec->name, dest_off); + return -1; + } + } + + return 0; +} + static void mark_rodata(struct objtool_file *file) { struct section *sec; @@ -1346,6 +1396,10 @@ static int decode_sections(struct objtool_file *file) if (ret) return ret; + ret = read_intra_function_calls(file); + if (ret) + return ret; + ret = add_call_destinations(file); if (ret) return ret; -- 2.39.2 (Apple Git-143)