[ammarfaizi2-block:bp/bp/rc0+ 6/11] arch/x86/kernel/cpu/common.c:1415:10: error: 'x86_cap_flags' undeclared; did you mean 'x86_cap_flag'?

[ammarfaizi2-block:bp/bp/rc0+ 6/11] arch/x86/kernel/cpu/common.c:1415:10: error: 'x86_cap_flags' undeclared; did you mean 'x86_cap_flag'?

[kernel test robot]

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/20220329/202203292206.ICsY2RKX-lkp@intel.com/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 <lkp@intel.com>

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

Re: [ammarfaizi2-block:bp/bp/rc0+ 6/11] arch/x86/kernel/cpu/common.c:1415:10: error: 'x86_cap_flags' undeclared; did you mean 'x86_cap_flag'?

[Borislav Petkov]

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/20220329/202203292206.ICsY2RKX-lkp@intel.com/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 <lkp@intel.com>

Thanks for reporting, fixed:

---
From: Borislav Petkov <bp@suse.de>
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/202203292206.ICsY2RKX-lkp@intel.com ]

Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20220127115626.14179-2-bp@alien8.de
---
 .../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