[PATCH] x86: Kill some chicken bits

From: Borislav Petkov
Date: Tue Oct 20 2015 - 12:33:38 EST


From: Borislav Petkov <bp@xxxxxxx>

Those were added as, well, chicken bits in case some of those features
are b0rked and as a way for us to "chicken" out and disable them. Remove
those chicken bits now, as they're not needed anymore.

Requested-by: "H. Peter Anvin" <hpa@xxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
---
Documentation/kernel-parameters.txt | 10 ----------
arch/x86/kernel/cpu/common.c | 22 ----------------------
2 files changed, 32 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 22a4b687ea5b..0448d63e3269 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2362,8 +2362,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.

nocache [ARM]

- noclflush [BUGS=X86] Don't use the CLFLUSH instruction
-
nodelayacct [KNL] Disable per-task delay accounting

nodisconnect [HW,SCSI,M68K] Disables SCSI disconnects.
@@ -2379,14 +2377,6 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
noexec=on: enable non-executable mappings (default)
noexec=off: disable non-executable mappings

- nosmap [X86]
- Disable SMAP (Supervisor Mode Access Prevention)
- even if it is supported by processor.
-
- nosmep [X86]
- Disable SMEP (Supervisor Mode Execution Prevention)
- even if it is supported by processor.
-
noexec32 [X86-64]
This affects only 32-bit executables.
noexec32=on: enable non-executable mappings (default)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index de22ea7ff82f..610c84379d87 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -251,26 +251,12 @@ static inline void squash_the_stupid_serial_number(struct cpuinfo_x86 *c)
}
#endif

-static __init int setup_disable_smep(char *arg)
-{
- setup_clear_cpu_cap(X86_FEATURE_SMEP);
- return 1;
-}
-__setup("nosmep", setup_disable_smep);
-
static __always_inline void setup_smep(struct cpuinfo_x86 *c)
{
if (cpu_has(c, X86_FEATURE_SMEP))
cr4_set_bits(X86_CR4_SMEP);
}

-static __init int setup_disable_smap(char *arg)
-{
- setup_clear_cpu_cap(X86_FEATURE_SMAP);
- return 1;
-}
-__setup("nosmap", setup_disable_smap);
-
static __always_inline void setup_smap(struct cpuinfo_x86 *c)
{
unsigned long eflags;
@@ -1083,14 +1069,6 @@ static __init int setup_show_msr(char *arg)
}
__setup("show_msr=", setup_show_msr);

-static __init int setup_noclflush(char *arg)
-{
- setup_clear_cpu_cap(X86_FEATURE_CLFLUSH);
- setup_clear_cpu_cap(X86_FEATURE_CLFLUSHOPT);
- return 1;
-}
-__setup("noclflush", setup_noclflush);
-
void print_cpu_info(struct cpuinfo_x86 *c)
{
const char *vendor = NULL;
--
2.3.5

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