The following commit has been merged into the x86/cpu branch of tip:
Commit-ID: a734d9d653faf3ddfbe09ef30f31e8977418515c
Gitweb: https://git.kernel.org/tip/a734d9d653faf3ddfbe09ef30f31e8977418515c
Author: Sohil Mehta <sohil.mehta@xxxxxxxxx>
AuthorDate: Thu, 07 Nov 2024 23:30:00
Committer: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
CommitterDate: Wed, 04 Dec 2024 12:27:13 -08:00
x86/cpufeatures: Free up unused feature bits
Linux defined feature bits X86_FEATURE_P3 and X86_FEATURE_P4 are not
used anywhere. Commit f31d731e4467 ("x86: use X86_FEATURE_NOPL in
alternatives") got rid of the last usage in 2008. Remove the related
mappings and code.
Just like all X86_FEATURE bits, the raw bit numbers can be exposed to
userspace via MODULE_DEVICE_TABLE(). There is a very small theoretical
chance of userspace getting confused if these bits got reassigned and
changed logical meaning. But these bits were never used for a device
table, so it's highly unlikely this will ever happen in practice.
[ dhansen: clarify userspace visibility of these bits ]
Signed-off-by: Sohil Mehta <sohil.mehta@xxxxxxxxx>
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/all/20241107233000.2742619-1-sohil.mehta%40intel.com
---
arch/x86/include/asm/cpufeatures.h | 4 ++--
arch/x86/kernel/cpu/intel.c | 5 -----
2 files changed, 2 insertions(+), 7 deletions(-)
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 05e985c..de3f299 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -83,8 +83,8 @@
#define X86_FEATURE_CENTAUR_MCR ( 3*32+ 3) /* "centaur_mcr" Centaur MCRs (= MTRRs) */
#define X86_FEATURE_K8 ( 3*32+ 4) /* Opteron, Athlon64 */
#define X86_FEATURE_ZEN5 ( 3*32+ 5) /* CPU based on Zen5 microarchitecture */
-#define X86_FEATURE_P3 ( 3*32+ 6) /* P3 */
-#define X86_FEATURE_P4 ( 3*32+ 7) /* P4 */
+/* Free ( 3*32+ 6) */
+/* Free ( 3*32+ 7) */
#define X86_FEATURE_CONSTANT_TSC ( 3*32+ 8) /* "constant_tsc" TSC ticks at a constant rate */
#define X86_FEATURE_UP ( 3*32+ 9) /* "up" SMP kernel running on UP */
#define X86_FEATURE_ART ( 3*32+10) /* "art" Always running timer (ART) */
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c
index e7656cb..1c892eb 100644
--- a/arch/x86/kernel/cpu/intel.c
+++ b/arch/x86/kernel/cpu/intel.c
@@ -628,11 +628,6 @@ static void init_intel(struct cpuinfo_x86 *c)
if (p)
strcpy(c->x86_model_id, p);
}
-
- if (c->x86 == 15)
- set_cpu_cap(c, X86_FEATURE_P4);
- if (c->x86 == 6)
- set_cpu_cap(c, X86_FEATURE_P3);
#endif
/* Work around errata */
|