From: Sami Tolvanen <samitolvanen@google.com>
To: Masahiro Yamada <masahiroy@kernel.org>,
Will Deacon <will@kernel.org>,
Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Paul E. McKenney" <paulmck@kernel.org>,
Kees Cook <keescook@chromium.org>,
Nick Desaulniers <ndesaulniers@google.com>,
clang-built-linux@googlegroups.com,
kernel-hardening@lists.openwall.com, linux-arch@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-pci@vger.kernel.org, x86@kernel.org,
Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v4 04/29] objtool: Add a pass for generating __mcount_loc
Date: Tue, 29 Sep 2020 14:46:06 -0700 [thread overview]
Message-ID: <20200929214631.3516445-5-samitolvanen@google.com> (raw)
In-Reply-To: <20200929214631.3516445-1-samitolvanen@google.com>
From: Peter Zijlstra <peterz@infradead.org>
Add the --mcount option for generating __mcount_loc sections
needed for dynamic ftrace. Using this pass requires the kernel to
be compiled with -mfentry and CC_USING_NOP_MCOUNT to be defined
in Makefile.
Link: https://lore.kernel.org/lkml/20200625200235.GQ4781@hirez.programming.kicks-ass.net/
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
[Sami: rebased to mainline, dropped config changes, fixed to actually use
--mcount, and wrote a commit message.]
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
---
tools/objtool/builtin-check.c | 3 +-
tools/objtool/builtin.h | 2 +-
tools/objtool/check.c | 83 +++++++++++++++++++++++++++++++++++
tools/objtool/check.h | 1 +
tools/objtool/objtool.h | 1 +
5 files changed, 88 insertions(+), 2 deletions(-)
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 7a44174967b5..71595cf4946d 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -18,7 +18,7 @@
#include "builtin.h"
#include "objtool.h"
-bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats, validate_dup, vmlinux;
+bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats, validate_dup, vmlinux, mcount;
static const char * const check_usage[] = {
"objtool check [<options>] file.o",
@@ -35,6 +35,7 @@ const struct option check_options[] = {
OPT_BOOLEAN('s', "stats", &stats, "print statistics"),
OPT_BOOLEAN('d', "duplicate", &validate_dup, "duplicate validation for vmlinux.o"),
OPT_BOOLEAN('l', "vmlinux", &vmlinux, "vmlinux.o validation"),
+ OPT_BOOLEAN('M', "mcount", &mcount, "generate __mcount_loc"),
OPT_END(),
};
diff --git a/tools/objtool/builtin.h b/tools/objtool/builtin.h
index 85c979caa367..94565a72b701 100644
--- a/tools/objtool/builtin.h
+++ b/tools/objtool/builtin.h
@@ -8,7 +8,7 @@
#include <subcmd/parse-options.h>
extern const struct option check_options[];
-extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats, validate_dup, vmlinux;
+extern bool no_fp, no_unreachable, retpoline, module, backtrace, uaccess, stats, validate_dup, vmlinux, mcount;
extern int cmd_check(int argc, const char **argv);
extern int cmd_orc(int argc, const char **argv);
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index 90a66891441a..ff0cd4d27d40 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -433,6 +433,65 @@ static int add_dead_ends(struct objtool_file *file)
return 0;
}
+static int create_mcount_loc_sections(struct objtool_file *file)
+{
+ struct section *sec, *reloc_sec;
+ struct reloc *reloc;
+ unsigned long *loc;
+ struct instruction *insn;
+ int idx;
+
+ sec = find_section_by_name(file->elf, "__mcount_loc");
+ if (sec) {
+ INIT_LIST_HEAD(&file->mcount_loc_list);
+ WARN("file already has __mcount_loc section, skipping");
+ return 0;
+ }
+
+ if (list_empty(&file->mcount_loc_list))
+ return 0;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->mcount_loc_list, mcount_loc_node)
+ idx++;
+
+ sec = elf_create_section(file->elf, "__mcount_loc", sizeof(unsigned long), idx);
+ if (!sec)
+ return -1;
+
+ reloc_sec = elf_create_reloc_section(file->elf, sec, SHT_RELA);
+ if (!reloc_sec)
+ return -1;
+
+ idx = 0;
+ list_for_each_entry(insn, &file->mcount_loc_list, mcount_loc_node) {
+
+ loc = (unsigned long *)sec->data->d_buf + idx;
+ memset(loc, 0, sizeof(unsigned long));
+
+ reloc = malloc(sizeof(*reloc));
+ if (!reloc) {
+ perror("malloc");
+ return -1;
+ }
+ memset(reloc, 0, sizeof(*reloc));
+
+ reloc->sym = insn->sec->sym;
+ reloc->addend = insn->offset;
+ reloc->type = R_X86_64_64;
+ reloc->offset = idx * sizeof(unsigned long);
+ reloc->sec = reloc_sec;
+ elf_add_reloc(file->elf, reloc);
+
+ idx++;
+ }
+
+ if (elf_rebuild_reloc_section(file->elf, reloc_sec))
+ return -1;
+
+ return 0;
+}
+
/*
* Warnings shouldn't be reported for ignored functions.
*/
@@ -784,6 +843,22 @@ static int add_call_destinations(struct objtool_file *file)
insn->type = INSN_NOP;
}
+ if (mcount && !strcmp(insn->call_dest->name, "__fentry__")) {
+ if (reloc) {
+ reloc->type = R_NONE;
+ elf_write_reloc(file->elf, reloc);
+ }
+
+ elf_write_insn(file->elf, insn->sec,
+ insn->offset, insn->len,
+ arch_nop_insn(insn->len));
+
+ insn->type = INSN_NOP;
+
+ list_add_tail(&insn->mcount_loc_node,
+ &file->mcount_loc_list);
+ }
+
/*
* Whatever stack impact regular CALLs have, should be undone
* by the RETURN of the called function.
@@ -2791,6 +2866,7 @@ int check(const char *_objname, bool orc)
INIT_LIST_HEAD(&file.insn_list);
hash_init(file.insn_hash);
+ INIT_LIST_HEAD(&file.mcount_loc_list);
file.c_file = !vmlinux && find_section_by_name(file.elf, ".comment");
file.ignore_unreachables = no_unreachable;
file.hints = false;
@@ -2838,6 +2914,13 @@ int check(const char *_objname, bool orc)
warnings += ret;
}
+ if (mcount) {
+ ret = create_mcount_loc_sections(&file);
+ if (ret < 0)
+ goto out;
+ warnings += ret;
+ }
+
if (orc) {
ret = create_orc(&file);
if (ret < 0)
diff --git a/tools/objtool/check.h b/tools/objtool/check.h
index 061aa96e15d3..b62afd3d970b 100644
--- a/tools/objtool/check.h
+++ b/tools/objtool/check.h
@@ -22,6 +22,7 @@ struct insn_state {
struct instruction {
struct list_head list;
struct hlist_node hash;
+ struct list_head mcount_loc_node;
struct section *sec;
unsigned long offset;
unsigned int len;
diff --git a/tools/objtool/objtool.h b/tools/objtool/objtool.h
index 528028a66816..427806079540 100644
--- a/tools/objtool/objtool.h
+++ b/tools/objtool/objtool.h
@@ -16,6 +16,7 @@ struct objtool_file {
struct elf *elf;
struct list_head insn_list;
DECLARE_HASHTABLE(insn_hash, 20);
+ struct list_head mcount_loc_list;
bool ignore_unreachables, c_file, hints, rodata;
};
--
2.28.0.709.gb0816b6eb0-goog
next prev parent reply other threads:[~2020-09-29 21:46 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-29 21:46 [PATCH v4 00/29] Add support for Clang LTO Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 01/29] RAS/CEC: Fix cec_init() prototype Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 02/29] x86/asm: Replace __force_order with memory clobber Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 03/29] kbuild: preprocess module linker script Sami Tolvanen
2020-09-29 21:46 ` Sami Tolvanen [this message]
2020-10-01 13:17 ` [PATCH v4 04/29] objtool: Add a pass for generating __mcount_loc Miroslav Benes
2020-10-01 13:36 ` Peter Zijlstra
2020-10-02 14:13 ` Josh Poimboeuf
2020-10-05 7:10 ` Miroslav Benes
2020-09-29 21:46 ` [PATCH v4 05/29] objtool: Don't autodetect vmlinux.o Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 06/29] tracing: move function tracer options to Kconfig Sami Tolvanen
2020-09-30 0:12 ` Steven Rostedt
2020-09-30 16:05 ` Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 07/29] tracing: add support for objtool mcount Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 08/29] x86, build: use " Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 09/29] arm64: disable recordmcount with DYNAMIC_FTRACE_WITH_REGS Sami Tolvanen
2020-09-30 9:58 ` Mark Rutland
2020-09-30 17:10 ` Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 10/29] treewide: remove DISABLE_LTO Sami Tolvanen
2020-09-30 20:45 ` Kees Cook
2020-09-29 21:46 ` [PATCH v4 11/29] kbuild: add support for Clang LTO Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 12/29] kbuild: lto: fix module versioning Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 13/29] kbuild: lto: postpone objtool Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 14/29] kbuild: lto: limit inlining Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 15/29] kbuild: lto: merge module sections Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 16/29] kbuild: lto: remove duplicate dependencies from .mod files Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 17/29] init: lto: ensure initcall ordering Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 18/29] init: lto: fix PREL32 relocations Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 19/29] PCI: Fix PREL32 relocations for LTO Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 20/29] modpost: lto: strip .lto from module names Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 21/29] scripts/mod: disable LTO for empty.c Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 22/29] efi/libstub: disable LTO Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 23/29] drivers/misc/lkdtm: disable LTO for rodata.o Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 24/29] arm64: vdso: disable LTO Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 25/29] KVM: arm64: disable LTO for the nVHE directory Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 26/29] arm64: allow LTO_CLANG and THINLTO to be selected Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 27/29] x86, vdso: disable LTO only for vDSO Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 28/29] x86, cpu: disable LTO for cpu.c Sami Tolvanen
2020-09-29 21:46 ` [PATCH v4 29/29] x86, build: allow LTO_CLANG and THINLTO to be selected Sami Tolvanen
2020-09-30 21:10 ` [PATCH v4 00/29] Add support for Clang LTO Kees Cook
2020-09-30 21:58 ` Nick Desaulniers
2020-09-30 22:12 ` Sami Tolvanen
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