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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2021-07-07 11:12:01 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2021-07-07 11:12:01 -0700 |
| commit | 1423e2660cf134a8f21f2451865a04792013e49e (patch) | |
| tree | 8dd93d1e767af1907929b650e1e0d1243865eafc /arch/x86/kernel/cpu/common.c | |
| parent | 4ea90317956718e0648e1f87e56530db809a5a04 (diff) | |
| parent | 93c2cdc975aab53c222472c5b96c2d41dbeb350c (diff) | |
Merge tag 'x86-fpu-2021-07-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fpu updates from Thomas Gleixner:
"Fixes and improvements for FPU handling on x86:
- Prevent sigaltstack out of bounds writes.
The kernel unconditionally writes the FPU state to the alternate
stack without checking whether the stack is large enough to
accomodate it.
Check the alternate stack size before doing so and in case it's too
small force a SIGSEGV instead of silently corrupting user space
data.
- MINSIGSTKZ and SIGSTKSZ are constants in signal.h and have never
been updated despite the fact that the FPU state which is stored on
the signal stack has grown over time which causes trouble in the
field when AVX512 is available on a CPU. The kernel does not expose
the minimum requirements for the alternate stack size depending on
the available and enabled CPU features.
ARM already added an aux vector AT_MINSIGSTKSZ for the same reason.
Add it to x86 as well.
- A major cleanup of the x86 FPU code. The recent discoveries of
XSTATE related issues unearthed quite some inconsistencies,
duplicated code and other issues.
The fine granular overhaul addresses this, makes the code more
robust and maintainable, which allows to integrate upcoming XSTATE
related features in sane ways"
* tag 'x86-fpu-2021-07-07' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (74 commits)
x86/fpu/xstate: Clear xstate header in copy_xstate_to_uabi_buf() again
x86/fpu/signal: Let xrstor handle the features to init
x86/fpu/signal: Handle #PF in the direct restore path
x86/fpu: Return proper error codes from user access functions
x86/fpu/signal: Split out the direct restore code
x86/fpu/signal: Sanitize copy_user_to_fpregs_zeroing()
x86/fpu/signal: Sanitize the xstate check on sigframe
x86/fpu/signal: Remove the legacy alignment check
x86/fpu/signal: Move initial checks into fpu__restore_sig()
x86/fpu: Mark init_fpstate __ro_after_init
x86/pkru: Remove xstate fiddling from write_pkru()
x86/fpu: Don't store PKRU in xstate in fpu_reset_fpstate()
x86/fpu: Remove PKRU handling from switch_fpu_finish()
x86/fpu: Mask PKRU from kernel XRSTOR[S] operations
x86/fpu: Hook up PKRU into ptrace()
x86/fpu: Add PKRU storage outside of task XSAVE buffer
x86/fpu: Dont restore PKRU in fpregs_restore_userspace()
x86/fpu: Rename xfeatures_mask_user() to xfeatures_mask_uabi()
x86/fpu: Move FXSAVE_LEAK quirk info __copy_kernel_to_fpregs()
x86/fpu: Rename __fpregs_load_activate() to fpregs_restore_userregs()
...
Diffstat (limited to 'arch/x86/kernel/cpu/common.c')
| -rw-r--r-- | arch/x86/kernel/cpu/common.c | 37 |
1 files changed, 17 insertions, 20 deletions
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index a99d00393206..64b805bd6a54 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -58,6 +58,7 @@ #include <asm/intel-family.h> #include <asm/cpu_device_id.h> #include <asm/uv/uv.h> +#include <asm/sigframe.h> #include "cpu.h" @@ -465,27 +466,22 @@ static bool pku_disabled; static __always_inline void setup_pku(struct cpuinfo_x86 *c) { - struct pkru_state *pk; + if (c == &boot_cpu_data) { + if (pku_disabled || !cpu_feature_enabled(X86_FEATURE_PKU)) + return; + /* + * Setting CR4.PKE will cause the X86_FEATURE_OSPKE cpuid + * bit to be set. Enforce it. + */ + setup_force_cpu_cap(X86_FEATURE_OSPKE); - /* check the boot processor, plus compile options for PKU: */ - if (!cpu_feature_enabled(X86_FEATURE_PKU)) - return; - /* checks the actual processor's cpuid bits: */ - if (!cpu_has(c, X86_FEATURE_PKU)) - return; - if (pku_disabled) + } else if (!cpu_feature_enabled(X86_FEATURE_OSPKE)) { return; + } cr4_set_bits(X86_CR4_PKE); - pk = get_xsave_addr(&init_fpstate.xsave, XFEATURE_PKRU); - if (pk) - pk->pkru = init_pkru_value; - /* - * Setting X86_CR4_PKE will cause the X86_FEATURE_OSPKE - * cpuid bit to be set. We need to ensure that we - * update that bit in this CPU's "cpu_info". - */ - set_cpu_cap(c, X86_FEATURE_OSPKE); + /* Load the default PKRU value */ + pkru_write_default(); } #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS @@ -1332,6 +1328,8 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c) fpu__init_system(c); + init_sigframe_size(); + #ifdef CONFIG_X86_32 /* * Regardless of whether PCID is enumerated, the SDM says @@ -1717,9 +1715,8 @@ void print_cpu_info(struct cpuinfo_x86 *c) } /* - * clearcpuid= was already parsed in fpu__init_parse_early_param. - * But we need to keep a dummy __setup around otherwise it would - * show up as an environment variable for init. + * clearcpuid= was already parsed in cpu_parse_early_param(). This dummy + * function prevents it from becoming an environment variable for init. */ static __init int setup_clearcpuid(char *arg) { |