tree: https://github.com/ammarfaizi2/linux-block bp/bp/rc0+
head: 2d784fc7295963360594f3de64446aa32841c694
commit: c3b9dcd01973935375ca9d0c67044bea7333d4ef [6/11] x86/cpu: Allow feature bit names from /proc/cpuinfo in clearcpuid=
config: i386-tinyconfig (https://download.01.org/0day-ci/archive/20220329/[email protected]/config)
compiler: gcc-9 (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0
reproduce (this is a W=1 build):
# https://github.com/ammarfaizi2/linux-block/commit/c3b9dcd01973935375ca9d0c67044bea7333d4ef
git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
git fetch --no-tags ammarfaizi2-block bp/bp/rc0+
git checkout c3b9dcd01973935375ca9d0c67044bea7333d4ef
# save the config file to linux build tree
mkdir build_dir
make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash arch/x86/kernel/cpu/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All errors (new ones prefixed by >>):
arch/x86/kernel/cpu/common.c: In function 'cpu_parse_early_param':
>> arch/x86/kernel/cpu/common.c:1415:10: error: 'x86_cap_flags' undeclared (first use in this function); did you mean 'x86_cap_flag'?
1415 | if (!x86_cap_flags[bit])
| ^~~~~~~~~~~~~
| x86_cap_flag
arch/x86/kernel/cpu/common.c:1415:10: note: each undeclared identifier is reported only once for each function it appears in
vim +1415 arch/x86/kernel/cpu/common.c
1385
1386 if (cmdline_find_option_bool(boot_command_line, "noxsave"))
1387 setup_clear_cpu_cap(X86_FEATURE_XSAVE);
1388
1389 if (cmdline_find_option_bool(boot_command_line, "noxsaveopt"))
1390 setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT);
1391
1392 if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
1393 setup_clear_cpu_cap(X86_FEATURE_XSAVES);
1394
1395 arglen = cmdline_find_option(boot_command_line, "clearcpuid", arg, sizeof(arg));
1396 if (arglen <= 0)
1397 return;
1398
1399 pr_info("Clearing CPUID bits:");
1400
1401 while (argptr) {
1402 bool found __maybe_unused = false;
1403 unsigned int bit;
1404
1405 opt = strsep(&argptr, ",");
1406
1407 /*
1408 * Handle naked numbers first for feature flags which don't
1409 * have names.
1410 */
1411 if (!kstrtouint(opt, 10, &bit)) {
1412 if (bit < NCAPINTS * 32) {
1413
1414 /* empty-string, i.e., ""-defined feature flags */
> 1415 if (!x86_cap_flags[bit])
1416 pr_cont(" " X86_CAP_FMT_NUM, x86_cap_flag_num(bit));
1417 else
1418 pr_cont(" " X86_CAP_FMT, x86_cap_flag(bit));
1419
1420 setup_clear_cpu_cap(bit);
1421 taint++;
1422 }
1423 /*
1424 * The assumption is that there are no feature names with only
1425 * numbers in the name thus go to the next argument.
1426 */
1427 continue;
1428 }
1429
--
0-DAY CI Kernel Test Service
https://01.org/lkp
On Tue, Mar 29, 2022 at 10:23:07PM +0800, kernel test robot wrote:
> tree: https://github.com/ammarfaizi2/linux-block bp/bp/rc0+
> head: 2d784fc7295963360594f3de64446aa32841c694
> commit: c3b9dcd01973935375ca9d0c67044bea7333d4ef [6/11] x86/cpu: Allow feature bit names from /proc/cpuinfo in clearcpuid=
> config: i386-tinyconfig (https://download.01.org/0day-ci/archive/20220329/[email protected]/config)
> compiler: gcc-9 (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0
> reproduce (this is a W=1 build):
> # https://github.com/ammarfaizi2/linux-block/commit/c3b9dcd01973935375ca9d0c67044bea7333d4ef
> git remote add ammarfaizi2-block https://github.com/ammarfaizi2/linux-block
> git fetch --no-tags ammarfaizi2-block bp/bp/rc0+
> git checkout c3b9dcd01973935375ca9d0c67044bea7333d4ef
> # save the config file to linux build tree
> mkdir build_dir
> make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash arch/x86/kernel/cpu/
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <[email protected]>
Thanks for reporting, fixed:
---
From: Borislav Petkov <[email protected]>
Date: Thu, 27 Jan 2022 12:56:21 +0100
Subject: [PATCH] x86/cpu: Allow feature bit names from /proc/cpuinfo in
clearcpuid=
Having to give the X86_FEATURE array indices in order to disable a
feature bit for testing is not really user-friendly. So accept the
feature bit names too.
Some feature bits don't have names so there the array indices are still
accepted, of course.
Clearing CPUID flags is not something which should be done in production
so taint the kernel too.
An exemplary cmdline would then be something like:
clearcpuid=de,440,smca,succory,bmi1,3dnow
("succory" is wrong on purpose). And it says:
[ ... ] Clearing CPUID bits: de 13:24 smca (unknown: succory) bmi1 3dnow
[ Fix CONFIG_X86_FEATURE_NAMES=n build error as reported by the 0day
robot: https://lore.kernel.org/r/[email protected] ]
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
---
.../admin-guide/kernel-parameters.txt | 11 +++-
arch/x86/include/asm/cpufeature.h | 7 +-
arch/x86/kernel/cpu/common.c | 64 +++++++++++++++----
3 files changed, 65 insertions(+), 17 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b7ccaa2ea867..bdad3dfd6a37 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -631,12 +631,17 @@
Defaults to zero when built as a module and to
10 seconds when built into the kernel.
- clearcpuid=BITNUM[,BITNUM...] [X86]
+ clearcpuid=X[,X...] [X86]
Disable CPUID feature X for the kernel. See
arch/x86/include/asm/cpufeatures.h for the valid bit
- numbers. Note the Linux specific bits are not necessarily
- stable over kernel options, but the vendor specific
+ numbers X. Note the Linux-specific bits are not necessarily
+ stable over kernel options, but the vendor-specific
ones should be.
+ X can also be a string as appearing in the flags: line
+ in /proc/cpuinfo which does not have the above
+ instability issue. However, not all features have names
+ in /proc/cpuinfo.
+ Note that using this option will taint your kernel.
Also note that user programs calling CPUID directly
or using the feature without checking anything
will still see it. This just prevents it from
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h
index 1261842d006c..66d3e3b1d24d 100644
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -34,14 +34,17 @@ enum cpuid_leafs
CPUID_8000_001F_EAX,
};
+#define X86_CAP_FMT_NUM "%d:%d"
+#define x86_cap_flag_num(flag) ((flag) >> 5), ((flag) & 31)
+
#ifdef CONFIG_X86_FEATURE_NAMES
extern const char * const x86_cap_flags[NCAPINTS*32];
extern const char * const x86_power_flags[32];
#define X86_CAP_FMT "%s"
#define x86_cap_flag(flag) x86_cap_flags[flag]
#else
-#define X86_CAP_FMT "%d:%d"
-#define x86_cap_flag(flag) ((flag) >> 5), ((flag) & 31)
+#define X86_CAP_FMT X86_CAP_FMT_NUM
+#define x86_cap_flag x86_cap_flag_num
#endif
/*
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index ed4417500700..69c7ea84b005 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -1368,8 +1368,8 @@ static void detect_nopl(void)
static void __init cpu_parse_early_param(void)
{
char arg[128];
- char *argptr = arg;
- int arglen, res, bit;
+ char *argptr = arg, *opt;
+ int arglen, taint = 0;
#ifdef CONFIG_X86_32
if (cmdline_find_option_bool(boot_command_line, "no387"))
@@ -1397,21 +1397,61 @@ static void __init cpu_parse_early_param(void)
return;
pr_info("Clearing CPUID bits:");
- do {
- res = get_option(&argptr, &bit);
- if (res == 0 || res == 3)
- break;
- /* If the argument was too long, the last bit may be cut off */
- if (res == 1 && arglen >= sizeof(arg))
- break;
+ while (argptr) {
+ bool found __maybe_unused = false;
+ unsigned int bit;
+
+ opt = strsep(&argptr, ",");
+
+ /*
+ * Handle naked numbers first for feature flags which don't
+ * have names.
+ */
+ if (!kstrtouint(opt, 10, &bit)) {
+ if (bit < NCAPINTS * 32) {
+
+#ifdef CONFIG_X86_FEATURE_NAMES
+ /* empty-string, i.e., ""-defined feature flags */
+ if (!x86_cap_flags[bit])
+ pr_cont(" " X86_CAP_FMT_NUM, x86_cap_flag_num(bit));
+ else
+#endif
+ pr_cont(" " X86_CAP_FMT, x86_cap_flag(bit));
+
+ setup_clear_cpu_cap(bit);
+ taint++;
+ }
+ /*
+ * The assumption is that there are no feature names with only
+ * numbers in the name thus go to the next argument.
+ */
+ continue;
+ }
+
+#ifdef CONFIG_X86_FEATURE_NAMES
+ for (bit = 0; bit < 32 * NCAPINTS; bit++) {
+ if (!x86_cap_flag(bit))
+ continue;
- if (bit >= 0 && bit < NCAPINTS * 32) {
- pr_cont(" " X86_CAP_FMT, x86_cap_flag(bit));
+ if (strcmp(x86_cap_flag(bit), opt))
+ continue;
+
+ pr_cont(" %s", opt);
setup_clear_cpu_cap(bit);
+ taint++;
+ found = true;
+ break;
}
- } while (res == 2);
+
+ if (!found)
+ pr_cont(" (unknown: %s)", opt);
+#endif
+ }
pr_cont("\n");
+
+ if (taint)
+ add_taint(TAINT_CPU_OUT_OF_SPEC, LOCKDEP_STILL_OK);
}
/*
--
2.35.1
--
Regards/Gruss,
Boris.
SUSE Software Solutions Germany GmbH, GF: Ivo Totev, HRB 36809, AG Nürnberg