From: Thomas Gleixner tglx@linutronix.de
Commit b3607269ff57fd3c9690cb25962c5e4b91a0fd3b upstream.
This cannot work and it's unclear how that ever made a difference.
init_fpstate.xsave.header.xfeatures is always 0 so get_xsave_addr() will always return a NULL pointer, which will prevent storing the default PKRU value in init_fpstate.
Signed-off-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Borislav Petkov bp@suse.de Reviewed-by: Borislav Petkov bp@suse.de Link: https://lkml.kernel.org/r/20210623121451.451391598@linutronix.de Reported-by: RAJESH DASARI raajeshdasari@gmail.com Signed-off-by: Thadeu Lima de Souza Cascardo cascardo@canonical.com ---
This has been reported to cause a WARNing since the backport of b81fac906a8f ("x86/fpu: Move FPU initialization into arch_cpu_finalize_init()").
a5eff7259790 was part of 5.2 and no older LTS kernels carry it, so not necessary on 4.19 or 4.14.
--- arch/x86/kernel/cpu/common.c | 5 ----- arch/x86/mm/pkeys.c | 6 ------ 2 files changed, 11 deletions(-)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index fcfe891c1e8e..0c0c2cb038ad 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -450,8 +450,6 @@ 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; @@ -462,9 +460,6 @@ 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 c6f84c0b5d7a..ca77af96033b 100644 --- a/arch/x86/mm/pkeys.c +++ b/arch/x86/mm/pkeys.c @@ -10,7 +10,6 @@
#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) { @@ -154,7 +153,6 @@ 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; @@ -177,10 +175,6 @@ 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; }