diff options
Diffstat (limited to 'arch/arm64/include/asm/uaccess.h')
| -rw-r--r-- | arch/arm64/include/asm/uaccess.h | 96 |
1 files changed, 23 insertions, 73 deletions
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 2fc9f0861769..14be5000c5a0 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -65,7 +65,6 @@ static inline void __uaccess_ttbr0_disable(void) ttbr &= ~TTBR_ASID_MASK; /* reserved_pg_dir placed before swapper_pg_dir */ write_sysreg(ttbr - RESERVED_SWAPPER_OFFSET, ttbr0_el1); - isb(); /* Set reserved ASID */ write_sysreg(ttbr, ttbr1_el1); isb(); @@ -89,7 +88,6 @@ static inline void __uaccess_ttbr0_enable(void) ttbr1 &= ~TTBR_ASID_MASK; /* safety measure */ ttbr1 |= ttbr0 & TTBR_ASID_MASK; write_sysreg(ttbr1, ttbr1_el1); - isb(); /* Restore user page table */ write_sysreg(ttbr0, ttbr0_el1); @@ -136,55 +134,9 @@ static inline void __uaccess_enable_hw_pan(void) CONFIG_ARM64_PAN)); } -/* - * The Tag Check Flag (TCF) mode for MTE is per EL, hence TCF0 - * affects EL0 and TCF affects EL1 irrespective of which TTBR is - * used. - * The kernel accesses TTBR0 usually with LDTR/STTR instructions - * when UAO is available, so these would act as EL0 accesses using - * TCF0. - * However futex.h code uses exclusives which would be executed as - * EL1, this can potentially cause a tag check fault even if the - * user disables TCF0. - * - * To address the problem we set the PSTATE.TCO bit in uaccess_enable() - * and reset it in uaccess_disable(). - * - * The Tag check override (TCO) bit disables temporarily the tag checking - * preventing the issue. - */ -static inline void __uaccess_disable_tco(void) -{ - asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(0), - ARM64_MTE, CONFIG_KASAN_HW_TAGS)); -} - -static inline void __uaccess_enable_tco(void) -{ - asm volatile(ALTERNATIVE("nop", SET_PSTATE_TCO(1), - ARM64_MTE, CONFIG_KASAN_HW_TAGS)); -} - -/* - * These functions disable tag checking only if in MTE async mode - * since the sync mode generates exceptions synchronously and the - * nofault or load_unaligned_zeropad can handle them. - */ -static inline void __uaccess_disable_tco_async(void) -{ - if (system_uses_mte_async_or_asymm_mode()) - __uaccess_disable_tco(); -} - -static inline void __uaccess_enable_tco_async(void) -{ - if (system_uses_mte_async_or_asymm_mode()) - __uaccess_enable_tco(); -} - static inline void uaccess_disable_privileged(void) { - __uaccess_disable_tco(); + mte_disable_tco(); if (uaccess_ttbr0_disable()) return; @@ -194,7 +146,7 @@ static inline void uaccess_disable_privileged(void) static inline void uaccess_enable_privileged(void) { - __uaccess_enable_tco(); + mte_enable_tco(); if (uaccess_ttbr0_enable()) return; @@ -203,9 +155,11 @@ static inline void uaccess_enable_privileged(void) } /* - * Sanitise a uaccess pointer such that it becomes NULL if above the maximum - * user address. In case the pointer is tagged (has the top byte set), untag - * the pointer before checking. + * Sanitize a uaccess pointer such that it cannot reach any kernel address. + * + * Clearing bit 55 ensures the pointer cannot address any portion of the TTBR1 + * address range (i.e. any kernel address), and either the pointer falls within + * the TTBR0 address range or must cause a fault. */ #define uaccess_mask_ptr(ptr) (__typeof__(ptr))__uaccess_mask_ptr(ptr) static inline void __user *__uaccess_mask_ptr(const void __user *ptr) @@ -213,14 +167,12 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr) void __user *safe_ptr; asm volatile( - " bics xzr, %3, %2\n" - " csel %0, %1, xzr, eq\n" - : "=&r" (safe_ptr) - : "r" (ptr), "r" (TASK_SIZE_MAX - 1), - "r" (untagged_addr(ptr)) - : "cc"); - - csdb(); + " bic %0, %1, %2\n" + : "=r" (safe_ptr) + : "r" (ptr), + "i" (BIT(55)) + ); + return safe_ptr; } @@ -237,7 +189,7 @@ static inline void __user *__uaccess_mask_ptr(const void __user *ptr) "1: " load " " reg "1, [%2]\n" \ "2:\n" \ _ASM_EXTABLE_##type##ACCESS_ERR_ZERO(1b, 2b, %w0, %w1) \ - : "+r" (err), "=&r" (x) \ + : "+r" (err), "=r" (x) \ : "r" (addr)) #define __raw_get_mem(ldr, x, ptr, err, type) \ @@ -302,8 +254,8 @@ do { \ #define get_user __get_user /* - * We must not call into the scheduler between __uaccess_enable_tco_async() and - * __uaccess_disable_tco_async(). As `dst` and `src` may contain blocking + * We must not call into the scheduler between __mte_enable_tco_async() and + * __mte_disable_tco_async(). As `dst` and `src` may contain blocking * functions, we must evaluate these outside of the critical section. */ #define __get_kernel_nofault(dst, src, type, err_label) \ @@ -312,10 +264,10 @@ do { \ __typeof__(src) __gkn_src = (src); \ int __gkn_err = 0; \ \ - __uaccess_enable_tco_async(); \ + __mte_enable_tco_async(); \ __raw_get_mem("ldr", *((type *)(__gkn_dst)), \ (__force type *)(__gkn_src), __gkn_err, K); \ - __uaccess_disable_tco_async(); \ + __mte_disable_tco_async(); \ \ if (unlikely(__gkn_err)) \ goto err_label; \ @@ -327,7 +279,7 @@ do { \ "2:\n" \ _ASM_EXTABLE_##type##ACCESS_ERR(1b, 2b, %w0) \ : "+r" (err) \ - : "r" (x), "r" (addr)) + : "rZ" (x), "r" (addr)) #define __raw_put_mem(str, x, ptr, err, type) \ do { \ @@ -388,8 +340,8 @@ do { \ #define put_user __put_user /* - * We must not call into the scheduler between __uaccess_enable_tco_async() and - * __uaccess_disable_tco_async(). As `dst` and `src` may contain blocking + * We must not call into the scheduler between __mte_enable_tco_async() and + * __mte_disable_tco_async(). As `dst` and `src` may contain blocking * functions, we must evaluate these outside of the critical section. */ #define __put_kernel_nofault(dst, src, type, err_label) \ @@ -398,10 +350,10 @@ do { \ __typeof__(src) __pkn_src = (src); \ int __pkn_err = 0; \ \ - __uaccess_enable_tco_async(); \ + __mte_enable_tco_async(); \ __raw_put_mem("str", *((type *)(__pkn_src)), \ (__force type *)(__pkn_dst), __pkn_err, K); \ - __uaccess_disable_tco_async(); \ + __mte_disable_tco_async(); \ \ if (unlikely(__pkn_err)) \ goto err_label; \ @@ -449,8 +401,6 @@ extern long strncpy_from_user(char *dest, const char __user *src, long count); extern __must_check long strnlen_user(const char __user *str, long n); #ifdef CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE -struct page; -void memcpy_page_flushcache(char *to, struct page *page, size_t offset, size_t len); extern unsigned long __must_check __copy_user_flushcache(void *to, const void __user *from, unsigned long n); static inline int __copy_from_user_flushcache(void *dst, const void __user *src, unsigned size) |