[PATCH AUTOSEL 5.5 06/28] kconfig: introduce m32-flag and m64-flag

[PATCH AUTOSEL 5.5 06/28] kconfig: introduce m32-flag and m64-flag

[Sasha Levin]

From: Masahiro Yamada <masahiroy@kernel.org>

[ Upstream commit 8cc4fd73501d9f1370c3eebb70cfe8cc9e24062b ]

When a compiler supports multiple architectures, some compiler features
can be dependent on the target architecture.

This is typical for Clang, which supports multiple LLVM backends.
Even for GCC, we need to take care of biarch compiler cases.

It is not a problem when we evaluate cc-option in Makefiles because
cc-option is tested against the flag in question + $(KBUILD_CFLAGS).

The cc-option in Kconfig, on the other hand, does not accumulate
tested flags. Due to this simplification, it could potentially test
cc-option against a different target.

At first, Kconfig always evaluated cc-option against the host
architecture.

Since commit e8de12fb7cde ("kbuild: Check for unknown options with
cc-option usage in Kconfig and clang"), in case of cross-compiling
with Clang, the target triple is correctly passed to Kconfig.

The case with biarch GCC (and native build with Clang) is still not
handled properly. We need to pass some flags to specify the target
machine bit.

Due to the design, all the macros in Kconfig are expanded in the
parse stage, where we do not know the target bit size yet.

For example, arch/x86/Kconfig allows a user to toggle CONFIG_64BIT.
If a compiler flag -foo depends on the machine bit, it must be tested
twice, one with -m32 and the other with -m64.

However, -m32/-m64 are not always recognized. So, this commits adds
m64-flag and m32-flag macros. They expand to -m32, -m64, respectively
if supported. Or, they expand to an empty string if unsupported.

The typical usage is like this:

  config FOO
          bool
          default $(cc-option,$(m64-flag) -foo) if 64BIT
          default $(cc-option,$(m32-flag) -foo)

This is clumsy, but there is no elegant way to handle this in the
current static macro expansion.

There was discussion for static functions vs dynamic functions.
The consensus was to go as far as possible with the static functions.
(https://lkml.org/lkml/2018/3/2/22)

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Tested-by: George Spelvin <lkml@sdf.org>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 scripts/Kconfig.include | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/scripts/Kconfig.include b/scripts/Kconfig.include
index bfb44b265a948..77a69ba9cd198 100644
--- a/scripts/Kconfig.include
+++ b/scripts/Kconfig.include
@@ -40,3 +40,10 @@ $(error-if,$(success, $(LD) -v | grep -q gold), gold linker '$(LD)' not supporte
 
 # gcc version including patch level
 gcc-version := $(shell,$(srctree)/scripts/gcc-version.sh $(CC))
+
+# machine bit flags
+#  $(m32-flag): -m32 if the compiler supports it, or an empty string otherwise.
+#  $(m64-flag): -m64 if the compiler supports it, or an empty string otherwise.
+cc-option-bit = $(if-success,$(CC) -Werror $(1) -E -x c /dev/null -o /dev/null,$(1))
+m32-flag := $(cc-option-bit,-m32)
+m64-flag := $(cc-option-bit,-m64)
-- 
2.20.1

[PATCH AUTOSEL 5.5 16/28] modpost: Get proper section index by get_secindex() instead of st_shndx

[Sasha Levin]

From: Xiao Yang <yangx.jy@cn.fujitsu.com>

[ Upstream commit 4b8a5cfb5fd375cf4c7502a18f0096ed2881be27 ]

(uint16_t) st_shndx is limited to 65535(i.e. SHN_XINDEX) so sym_get_data() gets
wrong section index by st_shndx if requested symbol contains extended section
index that is more than 65535.  In this case, we need to get proper section index
by .symtab_shndx section.

Module.symvers generated by building kernel with "-ffunction-sections -fdata-sections"
shows the issue.

Fixes: 56067812d5b0 ("kbuild: modversions: add infrastructure for emitting relative CRCs")
Fixes: e84f9fbbece1 ("modpost: refactor namespace_from_kstrtabns() to not hard-code section name")
Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 scripts/mod/modpost.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 6e892c93d104a..90aaf29c61a0f 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -307,7 +307,8 @@ static const char *sec_name(struct elf_info *elf, int secindex)
 
 static void *sym_get_data(const struct elf_info *info, const Elf_Sym *sym)
 {
-	Elf_Shdr *sechdr = &info->sechdrs[sym->st_shndx];
+	unsigned int secindex = get_secindex(info, sym);
+	Elf_Shdr *sechdr = &info->sechdrs[secindex];
 	unsigned long offset;
 
 	offset = sym->st_value;
-- 
2.20.1

[PATCH AUTOSEL 5.5 23/28] kconfig: Add yes2modconfig and mod2yesconfig targets.

[Sasha Levin]

From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>

[ Upstream commit 89b9060987d988333de59dd218c9666bd7ee95a5 ]

Since kernel configs provided by syzbot are close to "make allyesconfig",
it takes long time to rebuild. This is especially waste of time when we
need to rebuild for many times (e.g. doing manual printk() inspection,
bisect operations).

We can save time if we can exclude modules which are irrelevant to each
problem. But "make localmodconfig" cannot exclude modules which are built
into vmlinux because /sbin/lsmod output is used as the source of modules.

Therefore, this patch adds "make yes2modconfig" which converts from =y
to =m if possible. After confirming that the interested problem is still
reproducible, we can try "make localmodconfig" (and/or manually tune
based on "Modules linked in:" line) in order to exclude modules which are
irrelevant to the interested problem. While we are at it, this patch also
adds "make mod2yesconfig" which converts from =m to =y in case someone
wants to convert from =m to =y after "make localmodconfig".

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 scripts/kconfig/Makefile   |  4 +++-
 scripts/kconfig/conf.c     | 16 ++++++++++++++++
 scripts/kconfig/confdata.c | 16 ++++++++++++++++
 scripts/kconfig/lkc.h      |  3 +++
 4 files changed, 38 insertions(+), 1 deletion(-)

diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
index 2f1a59fa51694..811fb930b93bc 100644
--- a/scripts/kconfig/Makefile
+++ b/scripts/kconfig/Makefile
@@ -67,7 +67,7 @@ localyesconfig localmodconfig: $(obj)/conf
 #  deprecated for external use
 simple-targets := oldconfig allnoconfig allyesconfig allmodconfig \
 	alldefconfig randconfig listnewconfig olddefconfig syncconfig \
-	helpnewconfig
+	helpnewconfig yes2modconfig mod2yesconfig
 
 PHONY += $(simple-targets)
 
@@ -135,6 +135,8 @@ help:
 	@echo  '  allmodconfig	  - New config selecting modules when possible'
 	@echo  '  alldefconfig    - New config with all symbols set to default'
 	@echo  '  randconfig	  - New config with random answer to all options'
+	@echo  '  yes2modconfig	  - Change answers from yes to mod if possible'
+	@echo  '  mod2yesconfig	  - Change answers from mod to yes if possible'
 	@echo  '  listnewconfig   - List new options'
 	@echo  '  helpnewconfig   - List new options and help text'
 	@echo  '  olddefconfig	  - Same as oldconfig but sets new symbols to their'
diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
index 1f89bf1558ce2..f6e548b8f7955 100644
--- a/scripts/kconfig/conf.c
+++ b/scripts/kconfig/conf.c
@@ -34,6 +34,8 @@ enum input_mode {
 	listnewconfig,
 	helpnewconfig,
 	olddefconfig,
+	yes2modconfig,
+	mod2yesconfig,
 };
 static enum input_mode input_mode = oldaskconfig;
 
@@ -467,6 +469,8 @@ static struct option long_opts[] = {
 	{"listnewconfig",   no_argument,       NULL, listnewconfig},
 	{"helpnewconfig",   no_argument,       NULL, helpnewconfig},
 	{"olddefconfig",    no_argument,       NULL, olddefconfig},
+	{"yes2modconfig",   no_argument,       NULL, yes2modconfig},
+	{"mod2yesconfig",   no_argument,       NULL, mod2yesconfig},
 	{NULL, 0, NULL, 0}
 };
 
@@ -489,6 +493,8 @@ static void conf_usage(const char *progname)
 	printf("  --allmodconfig          New config where all options are answered with mod\n");
 	printf("  --alldefconfig          New config with all symbols set to default\n");
 	printf("  --randconfig            New config with random answer to all options\n");
+	printf("  --yes2modconfig         Change answers from yes to mod if possible\n");
+	printf("  --mod2yesconfig         Change answers from mod to yes if possible\n");
 }
 
 int main(int ac, char **av)
@@ -553,6 +559,8 @@ int main(int ac, char **av)
 		case listnewconfig:
 		case helpnewconfig:
 		case olddefconfig:
+		case yes2modconfig:
+		case mod2yesconfig:
 			break;
 		case '?':
 			conf_usage(progname);
@@ -587,6 +595,8 @@ int main(int ac, char **av)
 	case listnewconfig:
 	case helpnewconfig:
 	case olddefconfig:
+	case yes2modconfig:
+	case mod2yesconfig:
 		conf_read(NULL);
 		break;
 	case allnoconfig:
@@ -660,6 +670,12 @@ int main(int ac, char **av)
 		break;
 	case savedefconfig:
 		break;
+	case yes2modconfig:
+		conf_rewrite_mod_or_yes(def_y2m);
+		break;
+	case mod2yesconfig:
+		conf_rewrite_mod_or_yes(def_m2y);
+		break;
 	case oldaskconfig:
 		rootEntry = &rootmenu;
 		conf(&rootmenu);
diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index 17298239e3633..eb1efa3abdee6 100644
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -1362,3 +1362,19 @@ bool conf_set_all_new_symbols(enum conf_def_mode mode)
 
 	return has_changed;
 }
+
+void conf_rewrite_mod_or_yes(enum conf_def_mode mode)
+{
+	struct symbol *sym;
+	int i;
+	tristate old_val = (mode == def_y2m) ? yes : mod;
+	tristate new_val = (mode == def_y2m) ? mod : yes;
+
+	for_all_symbols(i, sym) {
+		if (sym_get_type(sym) == S_TRISTATE &&
+		    sym->def[S_DEF_USER].tri == old_val) {
+			sym->def[S_DEF_USER].tri = new_val;
+			sym_add_change_count(1);
+		}
+	}
+}
diff --git a/scripts/kconfig/lkc.h b/scripts/kconfig/lkc.h
index 4fb16f3166268..2bcc7bde6a338 100644
--- a/scripts/kconfig/lkc.h
+++ b/scripts/kconfig/lkc.h
@@ -34,6 +34,8 @@ enum conf_def_mode {
 	def_default,
 	def_yes,
 	def_mod,
+	def_y2m,
+	def_m2y,
 	def_no,
 	def_random
 };
@@ -52,6 +54,7 @@ const char *conf_get_configname(void);
 void sym_set_change_count(int count);
 void sym_add_change_count(int count);
 bool conf_set_all_new_symbols(enum conf_def_mode mode);
+void conf_rewrite_mod_or_yes(enum conf_def_mode mode);
 void set_all_choice_values(struct symbol *csym);
 
 /* confdata.c and expr.c */
-- 
2.20.1

Re: [PATCH AUTOSEL 5.5 23/28] kconfig: Add yes2modconfig and mod2yesconfig targets.

[Tetsuo Handa]

Hello.

I'm fine with backporting this patch. But if you want to backport this patch, please also
backport 089b7d890f972f6b ("kconfig: Invalidate all symbols after changing to y or m.")
which actually makes this patch functional.

On 2020/03/27 8:23, Sasha Levin wrote:
> From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
> 
> [ Upstream commit 89b9060987d988333de59dd218c9666bd7ee95a5 ]
> 
> Since kernel configs provided by syzbot are close to "make allyesconfig",
> it takes long time to rebuild. This is especially waste of time when we
> need to rebuild for many times (e.g. doing manual printk() inspection,
> bisect operations).
> 
> We can save time if we can exclude modules which are irrelevant to each
> problem. But "make localmodconfig" cannot exclude modules which are built
> into vmlinux because /sbin/lsmod output is used as the source of modules.
> 
> Therefore, this patch adds "make yes2modconfig" which converts from =y
> to =m if possible. After confirming that the interested problem is still
> reproducible, we can try "make localmodconfig" (and/or manually tune
> based on "Modules linked in:" line) in order to exclude modules which are
> irrelevant to the interested problem. While we are at it, this patch also
> adds "make mod2yesconfig" which converts from =m to =y in case someone
> wants to convert from =m to =y after "make localmodconfig".
> 
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> Signed-off-by: Sasha Levin <sashal@kernel.org>

Re: [PATCH AUTOSEL 5.5 23/28] kconfig: Add yes2modconfig and mod2yesconfig targets.

[Greg KH]

On Thu, Mar 26, 2020 at 07:23:52PM -0400, Sasha Levin wrote:
> From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
> 
> [ Upstream commit 89b9060987d988333de59dd218c9666bd7ee95a5 ]
> 
> Since kernel configs provided by syzbot are close to "make allyesconfig",
> it takes long time to rebuild. This is especially waste of time when we
> need to rebuild for many times (e.g. doing manual printk() inspection,
> bisect operations).
> 
> We can save time if we can exclude modules which are irrelevant to each
> problem. But "make localmodconfig" cannot exclude modules which are built
> into vmlinux because /sbin/lsmod output is used as the source of modules.
> 
> Therefore, this patch adds "make yes2modconfig" which converts from =y
> to =m if possible. After confirming that the interested problem is still
> reproducible, we can try "make localmodconfig" (and/or manually tune
> based on "Modules linked in:" line) in order to exclude modules which are
> irrelevant to the interested problem. While we are at it, this patch also
> adds "make mod2yesconfig" which converts from =m to =y in case someone
> wants to convert from =m to =y after "make localmodconfig".
> 
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Cc: Dmitry Vyukov <dvyukov@google.com>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
>  scripts/kconfig/Makefile   |  4 +++-
>  scripts/kconfig/conf.c     | 16 ++++++++++++++++
>  scripts/kconfig/confdata.c | 16 ++++++++++++++++
>  scripts/kconfig/lkc.h      |  3 +++
>  4 files changed, 38 insertions(+), 1 deletion(-)

Why did this patch get picked up by the autobot?  Because it referenced
syzbot?

It adds a new feature, that isn't really needed by any stable things, so
it should be dropped from your queues for all trees.

thanks,

greg k-h