diff options
| -rw-r--r-- | arch/arm64/include/asm/processor.h | 3 | ||||
| -rw-r--r-- | arch/arm64/include/asm/uaccess.h | 45 | ||||
| -rw-r--r-- | arch/arm64/kernel/entry.S | 4 | ||||
| -rw-r--r-- | arch/arm64/mm/fault.c | 4 |
4 files changed, 33 insertions, 23 deletions
diff --git a/arch/arm64/include/asm/processor.h b/arch/arm64/include/asm/processor.h index cee4ae25a5d1..dfefbf3fd9e3 100644 --- a/arch/arm64/include/asm/processor.h +++ b/arch/arm64/include/asm/processor.h @@ -21,6 +21,9 @@ #define TASK_SIZE_64 (UL(1) << VA_BITS) +#define KERNEL_DS UL(-1) +#define USER_DS (TASK_SIZE_64 - 1) + #ifndef __ASSEMBLY__ /* diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index 59fda5292936..f2fc026cffb4 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -35,10 +35,7 @@ #include <asm/compiler.h> #include <asm/extable.h> -#define KERNEL_DS (-1UL) #define get_ds() (KERNEL_DS) - -#define USER_DS TASK_SIZE_64 #define get_fs() (current_thread_info()->addr_limit) static inline void set_fs(mm_segment_t fs) @@ -66,22 +63,32 @@ static inline void set_fs(mm_segment_t fs) * Returns 1 if the range is valid, 0 otherwise. * * This is equivalent to the following test: - * (u65)addr + (u65)size <= current->addr_limit - * - * This needs 65-bit arithmetic. + * (u65)addr + (u65)size <= (u65)current->addr_limit + 1 */ -#define __range_ok(addr, size) \ -({ \ - unsigned long __addr = (unsigned long)(addr); \ - unsigned long flag, roksum; \ - __chk_user_ptr(addr); \ - asm("adds %1, %1, %3; ccmp %1, %4, #2, cc; cset %0, ls" \ - : "=&r" (flag), "=&r" (roksum) \ - : "1" (__addr), "Ir" (size), \ - "r" (current_thread_info()->addr_limit) \ - : "cc"); \ - flag; \ -}) +static inline unsigned long __range_ok(unsigned long addr, unsigned long size) +{ + unsigned long limit = current_thread_info()->addr_limit; + + __chk_user_ptr(addr); + asm volatile( + // A + B <= C + 1 for all A,B,C, in four easy steps: + // 1: X = A + B; X' = X % 2^64 + " adds %0, %0, %2\n" + // 2: Set C = 0 if X > 2^64, to guarantee X' > C in step 4 + " csel %1, xzr, %1, hi\n" + // 3: Set X' = ~0 if X >= 2^64. For X == 2^64, this decrements X' + // to compensate for the carry flag being set in step 4. For + // X > 2^64, X' merely has to remain nonzero, which it does. + " csinv %0, %0, xzr, cc\n" + // 4: For X < 2^64, this gives us X' - C - 1 <= 0, where the -1 + // comes from the carry in being clear. Otherwise, we are + // testing X' - C == 0, subject to the previous adjustments. + " sbcs xzr, %0, %1\n" + " cset %0, ls\n" + : "+r" (addr), "+r" (limit) : "Ir" (size) : "cc"); + + return addr; +} /* * When dealing with data aborts, watchpoints, or instruction traps we may end @@ -90,7 +97,7 @@ static inline void set_fs(mm_segment_t fs) */ #define untagged_addr(addr) sign_extend64(addr, 55) -#define access_ok(type, addr, size) __range_ok(addr, size) +#define access_ok(type, addr, size) __range_ok((unsigned long)(addr), size) #define user_addr_max get_fs #define _ASM_EXTABLE(from, to) \ diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 9b8635d9d7ae..17c15f741780 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -167,10 +167,10 @@ alternative_else_nop_endif .else add x21, sp, #S_FRAME_SIZE get_thread_info tsk - /* Save the task's original addr_limit and set USER_DS (TASK_SIZE_64) */ + /* Save the task's original addr_limit and set USER_DS */ ldr x20, [tsk, #TSK_TI_ADDR_LIMIT] str x20, [sp, #S_ORIG_ADDR_LIMIT] - mov x20, #TASK_SIZE_64 + mov x20, #USER_DS str x20, [tsk, #TSK_TI_ADDR_LIMIT] /* No need to reset PSTATE.UAO, hardware's already set it to 0 for us */ .endif /* \el == 0 */ diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 0e671ddf4855..af530eb9f2ed 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -240,7 +240,7 @@ static inline bool is_permission_fault(unsigned int esr, struct pt_regs *regs, if (fsc_type == ESR_ELx_FSC_PERM) return true; - if (addr < USER_DS && system_uses_ttbr0_pan()) + if (addr < TASK_SIZE && system_uses_ttbr0_pan()) return fsc_type == ESR_ELx_FSC_FAULT && (regs->pstate & PSR_PAN_BIT); @@ -414,7 +414,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, mm_flags |= FAULT_FLAG_WRITE; } - if (addr < USER_DS && is_permission_fault(esr, regs, addr)) { + if (addr < TASK_SIZE && is_permission_fault(esr, regs, addr)) { /* 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); |