Commit-ID: a5eff7259790d5314eff10563d6e59d358cce482 Gitweb: https://git.kernel.org/tip/a5eff7259790d5314eff10563d6e59d358cce482 Author: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> AuthorDate: Wed, 3 Apr 2019 18:41:56 +0200 Committer: Borislav Petkov <bp@xxxxxxx> CommitDate: Fri, 12 Apr 2019 20:21:10 +0200 x86/pkeys: Add PKRU value to init_fpstate The task's initial PKRU value is set partly for fpu__clear()/ copy_init_pkru_to_fpregs(). It is not part of init_fpstate.xsave and instead it is set explicitly. If the user removes the PKRU state from XSAVE in the signal handler then __fpu__restore_sig() will restore the missing bits from `init_fpstate' and initialize the PKRU value to 0. Add the `init_pkru_value' to `init_fpstate' so it is set to the init value in such a case. In theory copy_init_pkru_to_fpregs() could be removed because restoring the PKRU at return-to-userland should be enough. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Reviewed-by: Dave Hansen <dave.hansen@xxxxxxxxx> Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: "Chang S. Bae" <chang.seok.bae@xxxxxxxxx> Cc: Dominik Brodowski <linux@xxxxxxxxxxxxxxxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: "Jason A. Donenfeld" <Jason@xxxxxxxxx> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Cc: kvm ML <kvm@xxxxxxxxxxxxxxx> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Pavel Tatashin <pasha.tatashin@xxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxxx> Cc: x86-ml <x86@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20190403164156.19645-28-bigeasy@xxxxxxxxxxxxx --- arch/x86/kernel/cpu/common.c | 5 +++++ arch/x86/mm/pkeys.c | 6 ++++++ 2 files changed, 11 insertions(+) diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index cb28e98a0659..352fa19e6311 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -372,6 +372,8 @@ static bool pku_disabled; static __always_inline void setup_pku(struct cpuinfo_x86 *c) { + struct pkru_state *pk; + /* check the boot processor, plus compile options for PKU: */ if (!cpu_feature_enabled(X86_FEATURE_PKU)) return; @@ -382,6 +384,9 @@ static __always_inline void setup_pku(struct cpuinfo_x86 *c) return; cr4_set_bits(X86_CR4_PKE); + pk = get_xsave_addr(&init_fpstate.xsave, XFEATURE_PKRU); + if (pk) + pk->pkru = init_pkru_value; /* * Seting X86_CR4_PKE will cause the X86_FEATURE_OSPKE * cpuid bit to be set. We need to ensure that we diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c index 2ecbf4155f98..1dcfc91c8f0c 100644 --- a/arch/x86/mm/pkeys.c +++ b/arch/x86/mm/pkeys.c @@ -18,6 +18,7 @@ #include <asm/cpufeature.h> /* boot_cpu_has, ... */ #include <asm/mmu_context.h> /* vma_pkey() */ +#include <asm/fpu/internal.h> /* init_fpstate */ int __execute_only_pkey(struct mm_struct *mm) { @@ -161,6 +162,7 @@ static ssize_t init_pkru_read_file(struct file *file, char __user *user_buf, static ssize_t init_pkru_write_file(struct file *file, const char __user *user_buf, size_t count, loff_t *ppos) { + struct pkru_state *pk; char buf[32]; ssize_t len; u32 new_init_pkru; @@ -183,6 +185,10 @@ static ssize_t init_pkru_write_file(struct file *file, return -EINVAL; WRITE_ONCE(init_pkru_value, new_init_pkru); + pk = get_xsave_addr(&init_fpstate.xsave, XFEATURE_PKRU); + if (!pk) + return -EINVAL; + pk->pkru = new_init_pkru; return count; }
