diff options
Diffstat (limited to 'arch/arm64/mm/fault.c')
| -rw-r--r-- | arch/arm64/mm/fault.c | 92 |
1 files changed, 74 insertions, 18 deletions
diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 4c1a118c1d09..a13babf7daac 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -29,7 +29,9 @@ #include <linux/sched.h> #include <linux/highmem.h> #include <linux/perf_event.h> +#include <linux/preempt.h> +#include <asm/bug.h> #include <asm/cpufeature.h> #include <asm/exception.h> #include <asm/debug-monitors.h> @@ -64,21 +66,21 @@ void show_pte(struct mm_struct *mm, unsigned long addr) break; pud = pud_offset(pgd, addr); - printk(", *pud=%016llx", pud_val(*pud)); + pr_cont(", *pud=%016llx", pud_val(*pud)); if (pud_none(*pud) || pud_bad(*pud)) break; pmd = pmd_offset(pud, addr); - printk(", *pmd=%016llx", pmd_val(*pmd)); + pr_cont(", *pmd=%016llx", pmd_val(*pmd)); if (pmd_none(*pmd) || pmd_bad(*pmd)) break; pte = pte_offset_map(pmd, addr); - printk(", *pte=%016llx", pte_val(*pte)); + pr_cont(", *pte=%016llx", pte_val(*pte)); pte_unmap(pte); } while(0); - printk("\n"); + pr_cont("\n"); } #ifdef CONFIG_ARM64_HW_AFDBM @@ -131,6 +133,11 @@ int ptep_set_access_flags(struct vm_area_struct *vma, } #endif +static bool is_el1_instruction_abort(unsigned int esr) +{ + return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR; +} + /* * The kernel tried to access some page that wasn't present. */ @@ -139,8 +146,9 @@ static void __do_kernel_fault(struct mm_struct *mm, unsigned long addr, { /* * Are we prepared to handle this kernel fault? + * We are almost certainly not prepared to handle instruction faults. */ - if (fixup_exception(regs)) + if (!is_el1_instruction_abort(esr) && fixup_exception(regs)) return; /* @@ -202,8 +210,6 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re #define VM_FAULT_BADMAP 0x010000 #define VM_FAULT_BADACCESS 0x020000 -#define ESR_LNX_EXEC (1 << 24) - static int __do_page_fault(struct mm_struct *mm, unsigned long addr, unsigned int mm_flags, unsigned long vm_flags, struct task_struct *tsk) @@ -242,6 +248,26 @@ out: return fault; } +static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs) +{ + unsigned int ec = ESR_ELx_EC(esr); + unsigned int fsc_type = esr & ESR_ELx_FSC_TYPE; + + if (ec != ESR_ELx_EC_DABT_CUR && ec != ESR_ELx_EC_IABT_CUR) + return false; + + if (system_uses_ttbr0_pan()) + return fsc_type == ESR_ELx_FSC_FAULT && + (regs->pstate & PSR_PAN_BIT); + else + return fsc_type == ESR_ELx_FSC_PERM; +} + +static bool is_el0_instruction_abort(unsigned int esr) +{ + return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_LOW; +} + static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, struct pt_regs *regs) { @@ -268,19 +294,24 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, if (user_mode(regs)) mm_flags |= FAULT_FLAG_USER; - if (esr & ESR_LNX_EXEC) { + if (is_el0_instruction_abort(esr)) { vm_flags = VM_EXEC; } else if ((esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM)) { vm_flags = VM_WRITE; mm_flags |= FAULT_FLAG_WRITE; } - /* - * PAN bit set implies the fault happened in kernel space, but not - * in the arch's user access functions. - */ - if (IS_ENABLED(CONFIG_ARM64_PAN) && (regs->pstate & PSR_PAN_BIT)) - goto no_context; + if (addr < USER_DS && is_permission_fault(esr, regs)) { + /* regs->orig_addr_limit may be 0 if we entered from EL0 */ + if (regs->orig_addr_limit == KERNEL_DS) + die("Accessing user space memory with fs=KERNEL_DS", regs, esr); + + if (is_el1_instruction_abort(esr)) + die("Attempting to execute userspace memory", regs, esr); + + if (!search_exception_tables(regs->pc)) + die("Accessing user space memory outside uaccess.h routines", regs, esr); + } /* * As per x86, we may deadlock here. However, since the kernel only @@ -311,8 +342,11 @@ retry: * signal first. We do not need to release the mmap_sem because it * would already be released in __lock_page_or_retry in mm/filemap.c. */ - if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) + if ((fault & VM_FAULT_RETRY) && fatal_signal_pending(current)) { + if (!user_mode(regs)) + goto no_context; return 0; + } /* * Major/minor page fault accounting is only done on the initial @@ -429,7 +463,7 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs) return 1; } -static struct fault_info { +static const struct fault_info { int (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs); int sig; int code; @@ -442,7 +476,7 @@ static struct fault_info { { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 0 translation fault" }, { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 1 translation fault" }, { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 2 translation fault" }, - { do_page_fault, SIGSEGV, SEGV_MAPERR, "level 3 translation fault" }, + { do_translation_fault, SIGSEGV, SEGV_MAPERR, "level 3 translation fault" }, { do_bad, SIGBUS, 0, "unknown 8" }, { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 1 access flag fault" }, { do_page_fault, SIGSEGV, SEGV_ACCERR, "level 2 access flag fault" }, @@ -606,8 +640,30 @@ asmlinkage int __exception do_debug_exception(unsigned long addr, } #ifdef CONFIG_ARM64_PAN -void cpu_enable_pan(void *__unused) +int cpu_enable_pan(void *__unused) { + /* + * We modify PSTATE. This won't work from irq context as the PSTATE + * is discarded once we return from the exception. + */ + WARN_ON_ONCE(in_interrupt()); + config_sctlr_el1(SCTLR_EL1_SPAN, 0); + asm(SET_PSTATE_PAN(1)); + return 0; } #endif /* CONFIG_ARM64_PAN */ + +#ifdef CONFIG_ARM64_UAO +/* + * Kernel threads have fs=KERNEL_DS by default, and don't need to call + * set_fs(), devtmpfs in particular relies on this behaviour. + * We need to enable the feature at runtime (instead of adding it to + * PSR_MODE_EL1h) as the feature may not be implemented by the cpu. + */ +int cpu_enable_uao(void *__unused) +{ + asm(SET_PSTATE_UAO(1)); + return 0; +} +#endif /* CONFIG_ARM64_UAO */ |