[RFC PATCH v2 09/20] objtool: arm64: Implement command to invoke the decoder

madvenka
2022-05-24T00:17:53Z

Implement a built-in command called cmd_fpv() that can be invoked as
follows:

objtool fpv generate file.o

The built-in command invokes decode_instructions() to walk each function
and decode the instructions of the function.

Signed-off-by: Madhavan T. Venkataraman <madvenka@linux.microsoft.com>
---
tools/objtool/Build | 5 ++
tools/objtool/Makefile | 6 ++-
tools/objtool/builtin-fpv.c | 71 +++++++++++++++++++++++++
tools/objtool/fpv.c | 19 +++++++
tools/objtool/include/objtool/builtin.h | 1 +
tools/objtool/include/objtool/objtool.h | 1 +
tools/objtool/objtool.c | 12 ++++-
tools/objtool/weak.c | 5 ++
8 files changed, 117 insertions(+), 3 deletions(-)
create mode 100644 tools/objtool/builtin-fpv.c
create mode 100644 tools/objtool/fpv.c

diff --git a/tools/objtool/Build b/tools/objtool/Build
index 9c2a332f61f3..a491f51c40b4 100644
--- a/tools/objtool/Build
+++ b/tools/objtool/Build
@@ -15,9 +15,14 @@ objtool-$(SUBCMD_ORC) += decode.o
objtool-$(SUBCMD_ORC) += unwind_hints.o
objtool-$(SUBCMD_ORC) += orc_gen.o
objtool-$(SUBCMD_ORC) += orc_dump.o
+objtool-$(SUBCMD_FPV) += fpv.o
+objtool-$(SUBCMD_FPV) += cfi.o
+objtool-$(SUBCMD_FPV) += insn.o
+objtool-$(SUBCMD_FPV) += decode.o

objtool-y += builtin-check.o
objtool-y += builtin-orc.o
+objtool-y += builtin-fpv.o
objtool-y += elf.o
objtool-y += objtool.o

diff --git a/tools/objtool/Makefile b/tools/objtool/Makefile
index 0dbd397f319d..2511053245bc 100644
--- a/tools/objtool/Makefile
+++ b/tools/objtool/Makefile
@@ -47,7 +47,11 @@ ifeq ($(SRCARCH),x86)
SUBCMD_ORC := y
endif

-export SUBCMD_CHECK SUBCMD_ORC
+ifeq ($(SRCARCH),arm64)
+ SUBCMD_FPV := y
+endif
+
+export SUBCMD_CHECK SUBCMD_ORC SUBCMD_FPV
export srctree OUTPUT CFLAGS SRCARCH AWK
include $(srctree)/tools/build/Makefile.include

diff --git a/tools/objtool/builtin-fpv.c b/tools/objtool/builtin-fpv.c
new file mode 100644
index 000000000000..ff57dde39587
--- /dev/null
+++ b/tools/objtool/builtin-fpv.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Author: Madhavan T. Venkataraman (madvenka@linux.microsoft.com)
+ *
+ * Copyright (C) 2022 Microsoft Corporation
+ */
+
+/*
+ * objtool fp validation:
+ *
+ * This command analyzes a .o file and adds .orc_unwind and .orc_unwind_ip
+ * sections to it. The sections are used by the frame pointer-based in-kernel
+ * unwinder to validate the frame pointer.
+ */
+
+#include <string.h>
+#include <objtool/builtin.h>
+#include <objtool/objtool.h>
+
+static const char * const fpv_usage[] = {
+ "objtool fpv generate file.o",
+ NULL,
+};
+
+const struct option fpv_options[] = {
+ OPT_END(),
+};
+
+int cmd_fpv(int argc, const char **argv)
+{
+ const char *objname;
+ struct objtool_file *file;
+ int ret;
+
+ argc--; argv++;
+ if (argc <= 0)
+ usage_with_options(fpv_usage, fpv_options);
+
+ objname = argv[1];
+
+ file = objtool_open_read(objname);
+ if (!file)
+ return 1;
+
+ /* Supported architectures. */
+ switch (file->elf->ehdr.e_machine) {
+ case EM_AARCH64:
+ break;
+
+ default:
+ return 1;
+ }
+
+ if (!strncmp(argv[0], "gen", 3)) {
+ ret = fpv_decode(file);
+ if (ret)
+ return ret;
+
+ if (list_empty(&file->insn_list))
+ return 0;
+
+ if (!file->elf->changed)
+ return 0;
+
+ return elf_write(file->elf);
+ }
+
+ usage_with_options(fpv_usage, fpv_options);
+
+ return 0;
+}
diff --git a/tools/objtool/fpv.c b/tools/objtool/fpv.c
new file mode 100644
index 000000000000..76f0f2e611a8
--- /dev/null
+++ b/tools/objtool/fpv.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Author: Madhavan T. Venkataraman (madvenka@linux.microsoft.com)
+ *
+ * Copyright (C) 2022 Microsoft Corporation
+ */
+
+#include <string.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+
+#include <objtool/builtin.h>
+#include <objtool/insn.h>
+#include <objtool/warn.h>
+
+int fpv_decode(struct objtool_file *file)
+{
+ return decode_instructions(file);
+}
diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h
index c39dbfaef6dc..bfd99e08c33b 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -16,5 +16,6 @@ extern int cmd_parse_options(int argc, const char **argv, const char * const usa

extern int cmd_check(int argc, const char **argv);
extern int cmd_orc(int argc, const char **argv);
+extern int cmd_fpv(int argc, const char **argv);

#endif /* _BUILTIN_H */
diff --git a/tools/objtool/include/objtool/objtool.h b/tools/objtool/include/objtool/objtool.h
index 7a5c13a78f87..e00c8dcc6885 100644
--- a/tools/objtool/include/objtool/objtool.h
+++ b/tools/objtool/include/objtool/objtool.h
@@ -45,5 +45,6 @@ void objtool_pv_add(struct objtool_file *file, int idx, struct symbol *func);
int check(struct objtool_file *file);
int orc_dump(const char *objname);
int orc_create(struct objtool_file *file);
+int fpv_decode(struct objtool_file *file);

#endif /* _OBJTOOL_H */
diff --git a/tools/objtool/objtool.c b/tools/objtool/objtool.c
index b09946f4e1d6..974a9bc384e8 100644
--- a/tools/objtool/objtool.c
+++ b/tools/objtool/objtool.c
@@ -35,9 +35,17 @@ struct cmd_struct {
static const char objtool_usage_string[] =
"objtool COMMAND [ARGS]";

+static const char check_help[] =
+ "Perform stack metadata validation on an object file";
+static const char orc_help[] =
+ "Generate in-place ORC unwind tables for an object file";
+static const char fpv_help[] =
+ "Generate in-place FP validation tables for an object file";
+
static struct cmd_struct objtool_cmds[] = {
- {"check", cmd_check, "Perform stack metadata validation on an object file" },
- {"orc", cmd_orc, "Generate in-place ORC unwind tables for an object file" },
+ {"check", cmd_check, check_help },
+ {"orc", cmd_orc, orc_help },
+ {"fpv", cmd_fpv, fpv_help },
};

bool help;
diff --git a/tools/objtool/weak.c b/tools/objtool/weak.c
index 8314e824db4a..5e56ad5fe0fe 100644
--- a/tools/objtool/weak.c
+++ b/tools/objtool/weak.c
@@ -29,3 +29,8 @@ int __weak orc_create(struct objtool_file *file)
{
UNSUPPORTED("orc");
}
+
+int __weak fpv_decode(struct objtool_file *file)
+{
+ UNSUPPORTED("fpv");
+}
--
2.25.1