Some architectures (powerpc) may not support ftrace locations being nop'ed
out at build time. Introduce CONFIG_HAVE_OBJTOOL_NOP_MCOUNT for objtool, as
a means for architectures to enable nop'ing of ftrace locations. Add --mnop
as an option to objtool --mcount, to indicate support for the same.
Also, make sure that --mnop can be passed as an option to objtool only when
--mcount is passed.
Tested-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
Reviewed-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>
Acked-by: Josh Poimboeuf <jpoim...@kernel.org>
Reviewed-by: Christophe Leroy <christophe.le...@csgroup.eu>
Signed-off-by: Sathvika Vasireddy <s...@linux.ibm.com>
---
Makefile | 4 +++-
arch/x86/Kconfig | 1 +
kernel/trace/Kconfig | 7 +++++++
scripts/Makefile.lib | 3 +++
tools/objtool/builtin-check.c | 14 ++++++++++++++
tools/objtool/check.c | 19 ++++++++++---------
tools/objtool/include/objtool/builtin.h | 1 +
7 files changed, 39 insertions(+), 10 deletions(-)
diff --git a/Makefile b/Makefile
index d148a55bfd0f..53c2b715d0bf 100644
--- a/Makefile
+++ b/Makefile
@@ -933,7 +933,9 @@ ifdef CONFIG_FTRACE_MCOUNT_USE_CC
endif
endif
ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
- CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT
+ ifdef CONFIG_HAVE_OBJTOOL_NOP_MCOUNT
+ CC_FLAGS_USING += -DCC_USING_NOP_MCOUNT
+ endif
endif
ifdef CONFIG_FTRACE_MCOUNT_USE_RECORDMCOUNT
ifdef CONFIG_HAVE_C_RECORDMCOUNT
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 67745ceab0db..4be7c06a5d18 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -195,6 +195,7 @@ config X86
select HAVE_CONTEXT_TRACKING_USER_OFFSTACK if
HAVE_CONTEXT_TRACKING_USER
select HAVE_C_RECORDMCOUNT
select HAVE_OBJTOOL_MCOUNT if HAVE_OBJTOOL
+ select HAVE_OBJTOOL_NOP_MCOUNT if HAVE_OBJTOOL_MCOUNT
select HAVE_BUILDTIME_MCOUNT_SORT
select HAVE_DEBUG_KMEMLEAK
select HAVE_DMA_CONTIGUOUS
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig
index e9e95c790b8e..2b782321376a 100644
--- a/kernel/trace/Kconfig
+++ b/kernel/trace/Kconfig
@@ -82,6 +82,13 @@ config HAVE_OBJTOOL_MCOUNT
help
Arch supports objtool --mcount
+config HAVE_OBJTOOL_NOP_MCOUNT
+ bool
+ help
+ Arch supports the objtool options --mcount with --mnop.
+ An architecture can select this if it wants to enable nop'ing
+ of ftrace locations.
+
config HAVE_C_RECORDMCOUNT
bool
help
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 3aa384cec76b..658f541c2782 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -256,6 +256,9 @@ objtool-args-$(CONFIG_HAVE_JUMP_LABEL_HACK) +=
--hacks=jump_label
objtool-args-$(CONFIG_HAVE_NOINSTR_HACK) += --hacks=noinstr
objtool-args-$(CONFIG_X86_KERNEL_IBT) += --ibt
objtool-args-$(CONFIG_FTRACE_MCOUNT_USE_OBJTOOL) += --mcount
+ifdef CONFIG_FTRACE_MCOUNT_USE_OBJTOOL
+objtool-args-$(CONFIG_HAVE_OBJTOOL_NOP_MCOUNT) += --mnop
+endif
objtool-args-$(CONFIG_UNWINDER_ORC) += --orc
objtool-args-$(CONFIG_RETPOLINE) += --retpoline
objtool-args-$(CONFIG_RETHUNK) += --rethunk
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c
index 24fbe803a0d3..9bd347d3c244 100644
--- a/tools/objtool/builtin-check.c
+++ b/tools/objtool/builtin-check.c
@@ -82,6 +82,7 @@ const struct option check_options[] = {
OPT_BOOLEAN(0, "dry-run", &opts.dryrun, "don't write modifications"),
OPT_BOOLEAN(0, "link", &opts.link, "object is a linked object"),
OPT_BOOLEAN(0, "module", &opts.module, "object is part of a kernel
module"),
+ OPT_BOOLEAN(0, "mnop", &opts.mnop, "nop out mcount call sites"),
OPT_BOOLEAN(0, "no-unreachable", &opts.no_unreachable, "skip
'unreachable instruction' warnings"),
OPT_BOOLEAN(0, "sec-address", &opts.sec_address, "print section
addresses in warnings"),
OPT_BOOLEAN(0, "stats", &opts.stats, "print statistics"),
@@ -150,6 +151,16 @@ static bool opts_valid(void)
return false;
}
+static bool mnop_opts_valid(void)
+{
+ if (opts.mnop && !opts.mcount) {
+ ERROR("--mnop requires --mcount");
+ return false;
+ }
+
+ return true;
+}
+
static bool link_opts_valid(struct objtool_file *file)
{
if (opts.link)
@@ -198,6 +209,9 @@ int objtool_run(int argc, const char **argv)
if (!file)
return 1;
+ if (!mnop_opts_valid())
+ return 1;
+
if (!link_opts_valid(file))
return 1;
diff --git a/tools/objtool/check.c b/tools/objtool/check.c
index b64518c7c7b4..71cf4b4ba1da 100644
--- a/tools/objtool/check.c
+++ b/tools/objtool/check.c
@@ -1256,17 +1256,18 @@ static void annotate_call_site(struct objtool_file
*file,
if (opts.mcount && sym->fentry) {
if (sibling)
WARN_FUNC("Tail call to __fentry__ !?!?", insn->sec,
insn->offset);
+ if (opts.mnop) {
+ if (reloc) {
+ reloc->type = R_NONE;
+ elf_write_reloc(file->elf, reloc);
+ }
- 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));
+ elf_write_insn(file->elf, insn->sec,
+ insn->offset, insn->len,
+ arch_nop_insn(insn->len));
- insn->type = INSN_NOP;
+ insn->type = INSN_NOP;
+ }
list_add_tail(&insn->call_node, &file->mcount_loc_list);
return;
diff --git a/tools/objtool/include/objtool/builtin.h
b/tools/objtool/include/objtool/builtin.h
index 42a52f1a0add..0785707c5a92 100644
--- a/tools/objtool/include/objtool/builtin.h
+++ b/tools/objtool/include/objtool/builtin.h
@@ -31,6 +31,7 @@ struct opts {
bool backup;
bool dryrun;
bool link;
+ bool mnop;
bool module;
bool no_unreachable;
bool sec_address;
--
2.31.1
