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Merge tag 'mpx-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-mpx

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Pull x86 MPX removal from Dave Hansen:
 "MPX requires recompiling applications, which requires compiler
  support. Unfortunately, GCC 9.1 is expected to be be released without
  support for MPX. This means that there was only a relatively small
  window where folks could have ever used MPX. It failed to gain wide
  adoption in the industry, and Linux was the only mainstream OS to ever
  support it widely.

  Support for the feature may also disappear on future processors.

  This set completes the process that we started during the 5.4 merge
  window when the MPX prctl()s were removed. XSAVE support is left in
  place, which allows MPX-using KVM guests to continue to function"

* tag 'mpx-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-mpx:
  x86/mpx: remove MPX from arch/x86
  mm: remove arch_bprm_mm_init() hook
  x86/mpx: remove bounds exception code
  x86/mpx: remove build infrastructure
  x86/alternatives: add missing insn.h include
This commit is contained in:
Linus Torvalds
2020-01-30 16:11:50 -08:00
parent 35c222fd32 45fc24e89b
commit ccaaaf6fe5
24 changed files with 2 additions and 1697 deletions
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36
arch/x86/kernel/cpu/intel.c
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@@ -31,41 +31,6 @@
#include <asm/apic.h>
#endif
/*
* Just in case our CPU detection goes bad, or you have a weird system,
* allow a way to override the automatic disabling of MPX.
*/
static int forcempx;
static int __init forcempx_setup(char *__unused)
{
forcempx = 1;
return 1;
}
__setup("intel-skd-046-workaround=disable", forcempx_setup);
void check_mpx_erratum(struct cpuinfo_x86 *c)
{
if (forcempx)
return;
/*
* Turn off the MPX feature on CPUs where SMEP is not
* available or disabled.
*
* Works around Intel Erratum SKD046: "Branch Instructions
* May Initialize MPX Bound Registers Incorrectly".
*
* This might falsely disable MPX on systems without
* SMEP, like Atom processors without SMEP. But there
* is no such hardware known at the moment.
*/
if (cpu_has(c, X86_FEATURE_MPX) && !cpu_has(c, X86_FEATURE_SMEP)) {
setup_clear_cpu_cap(X86_FEATURE_MPX);
pr_warn("x86/mpx: Disabling MPX since SMEP not present\n");
}
}
/*
* Processors which have self-snooping capability can handle conflicting
* memory type across CPUs by snooping its own cache. However, there exists
@@ -330,7 +295,6 @@ static void early_init_intel(struct cpuinfo_x86 *c)
c->x86_coreid_bits = get_count_order((ebx >> 16) & 0xff);
}
check_mpx_erratum(c);
check_memory_type_self_snoop_errata(c);
/*