diff options
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/set_memory.h | 42 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/mcheck/mce-internal.h | 15 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/mcheck/mce.c | 38 |
3 files changed, 45 insertions, 50 deletions
diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h index bd090367236c..cf5e9124b45e 100644 --- a/arch/x86/include/asm/set_memory.h +++ b/arch/x86/include/asm/set_memory.h @@ -88,4 +88,46 @@ extern int kernel_set_to_readonly; void set_kernel_text_rw(void); void set_kernel_text_ro(void); +#ifdef CONFIG_X86_64 +static inline int set_mce_nospec(unsigned long pfn) +{ + unsigned long decoy_addr; + int rc; + + /* + * Mark the linear address as UC to make sure we don't log more + * errors because of speculative access to the page. + * We would like to just call: + * set_memory_uc((unsigned long)pfn_to_kaddr(pfn), 1); + * but doing that would radically increase the odds of a + * speculative access to the poison page because we'd have + * the virtual address of the kernel 1:1 mapping sitting + * around in registers. + * Instead we get tricky. We create a non-canonical address + * that looks just like the one we want, but has bit 63 flipped. + * This relies on set_memory_uc() properly sanitizing any __pa() + * results with __PHYSICAL_MASK or PTE_PFN_MASK. + */ + decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63)); + + rc = set_memory_uc(decoy_addr, 1); + if (rc) + pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn); + return rc; +} +#define set_mce_nospec set_mce_nospec + +/* Restore full speculative operation to the pfn. */ +static inline int clear_mce_nospec(unsigned long pfn) +{ + return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1); +} +#define clear_mce_nospec clear_mce_nospec +#else +/* + * Few people would run a 32-bit kernel on a machine that supports + * recoverable errors because they have too much memory to boot 32-bit. + */ +#endif + #endif /* _ASM_X86_SET_MEMORY_H */ diff --git a/arch/x86/kernel/cpu/mcheck/mce-internal.h b/arch/x86/kernel/cpu/mcheck/mce-internal.h index 374d1aa66952..ceb67cd5918f 100644 --- a/arch/x86/kernel/cpu/mcheck/mce-internal.h +++ b/arch/x86/kernel/cpu/mcheck/mce-internal.h @@ -113,21 +113,6 @@ static inline void mce_register_injector_chain(struct notifier_block *nb) { } static inline void mce_unregister_injector_chain(struct notifier_block *nb) { } #endif -#ifndef CONFIG_X86_64 -/* - * On 32-bit systems it would be difficult to safely unmap a poison page - * from the kernel 1:1 map because there are no non-canonical addresses that - * we can use to refer to the address without risking a speculative access. - * However, this isn't much of an issue because: - * 1) Few unmappable pages are in the 1:1 map. Most are in HIGHMEM which - * are only mapped into the kernel as needed - * 2) Few people would run a 32-bit kernel on a machine that supports - * recoverable errors because they have too much memory to boot 32-bit. - */ -static inline void mce_unmap_kpfn(unsigned long pfn) {} -#define mce_unmap_kpfn mce_unmap_kpfn -#endif - struct mca_config { bool dont_log_ce; bool cmci_disabled; diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index c102ad51025e..42a061ce1f5d 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -42,6 +42,7 @@ #include <linux/irq_work.h> #include <linux/export.h> #include <linux/jump_label.h> +#include <linux/set_memory.h> #include <asm/intel-family.h> #include <asm/processor.h> @@ -50,7 +51,6 @@ #include <asm/mce.h> #include <asm/msr.h> #include <asm/reboot.h> -#include <asm/set_memory.h> #include "mce-internal.h" @@ -108,10 +108,6 @@ static struct irq_work mce_irq_work; static void (*quirk_no_way_out)(int bank, struct mce *m, struct pt_regs *regs); -#ifndef mce_unmap_kpfn -static void mce_unmap_kpfn(unsigned long pfn); -#endif - /* * CPU/chipset specific EDAC code can register a notifier call here to print * MCE errors in a human-readable form. @@ -602,7 +598,7 @@ static int srao_decode_notifier(struct notifier_block *nb, unsigned long val, if (mce_usable_address(mce) && (mce->severity == MCE_AO_SEVERITY)) { pfn = mce->addr >> PAGE_SHIFT; if (!memory_failure(pfn, 0)) - mce_unmap_kpfn(pfn); + set_mce_nospec(pfn); } return NOTIFY_OK; @@ -1072,38 +1068,10 @@ static int do_memory_failure(struct mce *m) if (ret) pr_err("Memory error not recovered"); else - mce_unmap_kpfn(m->addr >> PAGE_SHIFT); + set_mce_nospec(m->addr >> PAGE_SHIFT); return ret; } -#ifndef mce_unmap_kpfn -static void mce_unmap_kpfn(unsigned long pfn) -{ - unsigned long decoy_addr; - - /* - * Unmap this page from the kernel 1:1 mappings to make sure - * we don't log more errors because of speculative access to - * the page. - * We would like to just call: - * set_memory_np((unsigned long)pfn_to_kaddr(pfn), 1); - * but doing that would radically increase the odds of a - * speculative access to the poison page because we'd have - * the virtual address of the kernel 1:1 mapping sitting - * around in registers. - * Instead we get tricky. We create a non-canonical address - * that looks just like the one we want, but has bit 63 flipped. - * This relies on set_memory_np() not checking whether we passed - * a legal address. - */ - - decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63)); - - if (set_memory_np(decoy_addr, 1)) - pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn); -} -#endif - /* * The actual machine check handler. This only handles real * exceptions when something got corrupted coming in through int 18. |