diff --git a/Documentation/arm64/tagged-pointers.txt b/Documentation/arm64/tagged-pointers.txt index d9995f1f51b3..a25a99e82bb1 100644 --- a/Documentation/arm64/tagged-pointers.txt +++ b/Documentation/arm64/tagged-pointers.txt @@ -11,24 +11,56 @@ in AArch64 Linux. The kernel configures the translation tables so that translations made via TTBR0 (i.e. userspace mappings) have the top byte (bits 63:56) of the virtual address ignored by the translation hardware. This frees up -this byte for application use, with the following caveats: +this byte for application use. - (1) The kernel requires that all user addresses passed to EL1 - are tagged with tag 0x00. This means that any syscall - parameters containing user virtual addresses *must* have - their top byte cleared before trapping to the kernel. - (2) Non-zero tags are not preserved when delivering signals. - This means that signal handlers in applications making use - of tags cannot rely on the tag information for user virtual - addresses being maintained for fields inside siginfo_t. - One exception to this rule is for signals raised in response - to watchpoint debug exceptions, where the tag information - will be preserved. +Passing tagged addresses to the kernel +-------------------------------------- - (3) Special care should be taken when using tagged pointers, - since it is likely that C compilers will not hazard two - virtual addresses differing only in the upper byte. +All interpretation of userspace memory addresses by the kernel assumes +an address tag of 0x00. + +This includes, but is not limited to, addresses found in: + + - pointer arguments to system calls, including pointers in structures + passed to system calls, + + - the stack pointer (sp), e.g. when interpreting it to deliver a + signal, + + - the frame pointer (x29) and frame records, e.g. when interpreting + them to generate a backtrace or call graph. + +Using non-zero address tags in any of these locations may result in an +error code being returned, a (fatal) signal being raised, or other modes +of failure. + +For these reasons, passing non-zero address tags to the kernel via +system calls is forbidden, and using a non-zero address tag for sp is +strongly discouraged. + +Programs maintaining a frame pointer and frame records that use non-zero +address tags may suffer impaired or inaccurate debug and profiling +visibility. + + +Preserving tags +--------------- + +Non-zero tags are not preserved when delivering signals. This means that +signal handlers in applications making use of tags cannot rely on the +tag information for user virtual addresses being maintained for fields +inside siginfo_t. One exception to this rule is for signals raised in +response to watchpoint debug exceptions, where the tag information will +be preserved. The architecture prevents the use of a tagged PC, so the upper byte will be set to a sign-extension of bit 55 on exception return. + + +Other considerations +-------------------- + +Special care should be taken when using tagged pointers, since it is +likely that C compilers will not hazard two virtual addresses differing +only in the upper byte. diff --git a/arch/arm/kernel/module.c b/arch/arm/kernel/module.c index 80254b47dc34..3ff571c2c71c 100644 --- a/arch/arm/kernel/module.c +++ b/arch/arm/kernel/module.c @@ -40,8 +40,15 @@ #ifdef CONFIG_MMU void *module_alloc(unsigned long size) { - void *p = __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END, - GFP_KERNEL, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE, + gfp_t gfp_mask = GFP_KERNEL; + void *p; + + /* Silence the initial allocation */ + if (IS_ENABLED(CONFIG_ARM_MODULE_PLTS)) + gfp_mask |= __GFP_NOWARN; + + p = __vmalloc_node_range(size, 1, MODULES_VADDR, MODULES_END, + gfp_mask, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE, __builtin_return_address(0)); if (!IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || p) return p; diff --git a/arch/arm64/include/asm/asm-uaccess.h b/arch/arm64/include/asm/asm-uaccess.h index df411f3e083c..ecd9788cd298 100644 --- a/arch/arm64/include/asm/asm-uaccess.h +++ b/arch/arm64/include/asm/asm-uaccess.h @@ -62,4 +62,13 @@ alternative_if ARM64_ALT_PAN_NOT_UAO alternative_else_nop_endif .endm +/* + * Remove the address tag from a virtual address, if present. + */ + .macro clear_address_tag, dst, addr + tst \addr, #(1 << 55) + bic \dst, \addr, #(0xff << 56) + csel \dst, \dst, \addr, eq + .endm + #endif diff --git a/arch/arm64/include/asm/atomic_lse.h b/arch/arm64/include/asm/atomic_lse.h index 7457ce082b5f..99fa69c9c3cf 100644 --- a/arch/arm64/include/asm/atomic_lse.h +++ b/arch/arm64/include/asm/atomic_lse.h @@ -322,7 +322,7 @@ static inline void atomic64_and(long i, atomic64_t *v) #define ATOMIC64_FETCH_OP_AND(name, mb, cl...) \ static inline long atomic64_fetch_and##name(long i, atomic64_t *v) \ { \ - register long x0 asm ("w0") = i; \ + register long x0 asm ("x0") = i; \ register atomic64_t *x1 asm ("x1") = v; \ \ asm volatile(ARM64_LSE_ATOMIC_INSN( \ @@ -394,7 +394,7 @@ ATOMIC64_OP_SUB_RETURN( , al, "memory") #define ATOMIC64_FETCH_OP_SUB(name, mb, cl...) \ static inline long atomic64_fetch_sub##name(long i, atomic64_t *v) \ { \ - register long x0 asm ("w0") = i; \ + register long x0 asm ("x0") = i; \ register atomic64_t *x1 asm ("x1") = v; \ \ asm volatile(ARM64_LSE_ATOMIC_INSN( \ diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h index 4e0497f581a0..0fe7e43b7fbc 100644 --- a/arch/arm64/include/asm/barrier.h +++ b/arch/arm64/include/asm/barrier.h @@ -42,25 +42,35 @@ #define __smp_rmb() dmb(ishld) #define __smp_wmb() dmb(ishst) -#define __smp_store_release(p, v) \ +#define __smp_store_release(p, v) \ do { \ + union { typeof(*p) __val; char __c[1]; } __u = \ + { .__val = (__force typeof(*p)) (v) }; \ compiletime_assert_atomic_type(*p); \ switch (sizeof(*p)) { \ case 1: \ asm volatile ("stlrb %w1, %0" \ - : "=Q" (*p) : "r" (v) : "memory"); \ + : "=Q" (*p) \ + : "r" (*(__u8 *)__u.__c) \ + : "memory"); \ break; \ case 2: \ asm volatile ("stlrh %w1, %0" \ - : "=Q" (*p) : "r" (v) : "memory"); \ + : "=Q" (*p) \ + : "r" (*(__u16 *)__u.__c) \ + : "memory"); \ break; \ case 4: \ asm volatile ("stlr %w1, %0" \ - : "=Q" (*p) : "r" (v) : "memory"); \ + : "=Q" (*p) \ + : "r" (*(__u32 *)__u.__c) \ + : "memory"); \ break; \ case 8: \ asm volatile ("stlr %1, %0" \ - : "=Q" (*p) : "r" (v) : "memory"); \ + : "=Q" (*p) \ + : "r" (*(__u64 *)__u.__c) \ + : "memory"); \ break; \ } \ } while (0) diff --git a/arch/arm64/include/asm/cmpxchg.h b/arch/arm64/include/asm/cmpxchg.h index 91b26d26af8a..ae852add053d 100644 --- a/arch/arm64/include/asm/cmpxchg.h +++ b/arch/arm64/include/asm/cmpxchg.h @@ -46,7 +46,7 @@ static inline unsigned long __xchg_case_##name(unsigned long x, \ " swp" #acq_lse #rel #sz "\t%" #w "3, %" #w "0, %2\n" \ __nops(3) \ " " #nop_lse) \ - : "=&r" (ret), "=&r" (tmp), "+Q" (*(u8 *)ptr) \ + : "=&r" (ret), "=&r" (tmp), "+Q" (*(unsigned long *)ptr) \ : "r" (x) \ : cl); \ \ diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index ba497172610d..7b8a04789cef 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -69,20 +69,21 @@ static inline void set_fs(mm_segment_t fs) */ #define __range_ok(addr, size) \ ({ \ + unsigned long __addr = (unsigned long __force)(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), \ + : "1" (__addr), "Ir" (size), \ "r" (current_thread_info()->addr_limit) \ : "cc"); \ flag; \ }) /* - * When dealing with data aborts or instruction traps we may end up with - * a tagged userland pointer. Clear the tag to get a sane pointer to pass - * on to access_ok(), for instance. + * When dealing with data aborts, watchpoints, or instruction traps we may end + * up with a tagged userland pointer. Clear the tag to get a sane pointer to + * pass on to access_ok(), for instance. */ #define untagged_addr(addr) sign_extend64(addr, 55) @@ -230,7 +231,7 @@ do { \ (err), ARM64_HAS_UAO); \ break; \ case 8: \ - __get_user_asm("ldr", "ldtr", "%", __gu_val, (ptr), \ + __get_user_asm("ldr", "ldtr", "%x", __gu_val, (ptr), \ (err), ARM64_HAS_UAO); \ break; \ default: \ @@ -297,7 +298,7 @@ do { \ (err), ARM64_HAS_UAO); \ break; \ case 8: \ - __put_user_asm("str", "sttr", "%", __pu_val, (ptr), \ + __put_user_asm("str", "sttr", "%x", __pu_val, (ptr), \ (err), ARM64_HAS_UAO); \ break; \ default: \ diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c index 657977e77ec8..f0e6d717885b 100644 --- a/arch/arm64/kernel/armv8_deprecated.c +++ b/arch/arm64/kernel/armv8_deprecated.c @@ -306,7 +306,8 @@ do { \ _ASM_EXTABLE(0b, 4b) \ _ASM_EXTABLE(1b, 4b) \ : "=&r" (res), "+r" (data), "=&r" (temp), "=&r" (temp2) \ - : "r" (addr), "i" (-EAGAIN), "i" (-EFAULT), \ + : "r" ((unsigned long)addr), "i" (-EAGAIN), \ + "i" (-EFAULT), \ "i" (__SWP_LL_SC_LOOPS) \ : "memory"); \ uaccess_disable(); \ diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 43512d4d7df2..b738880350f9 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -428,12 +428,13 @@ el1_da: /* * Data abort handling */ - mrs x0, far_el1 + mrs x3, far_el1 enable_dbg // re-enable interrupts if they were enabled in the aborted context tbnz x23, #7, 1f // PSR_I_BIT enable_irq 1: + clear_address_tag x0, x3 mov x2, sp // struct pt_regs bl do_mem_abort @@ -594,7 +595,7 @@ el0_da: // enable interrupts before calling the main handler enable_dbg_and_irq ct_user_exit - bic x0, x26, #(0xff << 56) + clear_address_tag x0, x26 mov x1, x25 mov x2, sp bl do_mem_abort diff --git a/arch/arm64/kernel/hw_breakpoint.c b/arch/arm64/kernel/hw_breakpoint.c index 0296e7924240..749f81779420 100644 --- a/arch/arm64/kernel/hw_breakpoint.c +++ b/arch/arm64/kernel/hw_breakpoint.c @@ -36,6 +36,7 @@ #include #include #include +#include /* Breakpoint currently in use for each BRP. */ static DEFINE_PER_CPU(struct perf_event *, bp_on_reg[ARM_MAX_BRP]); @@ -721,6 +722,8 @@ static u64 get_distance_from_watchpoint(unsigned long addr, u64 val, u64 wp_low, wp_high; u32 lens, lene; + addr = untagged_addr(addr); + lens = __ffs(ctrl->len); lene = __fls(ctrl->len); diff --git a/arch/arm64/kernel/module.c b/arch/arm64/kernel/module.c index c9a2ab446dc6..f035ff6fb223 100644 --- a/arch/arm64/kernel/module.c +++ b/arch/arm64/kernel/module.c @@ -32,11 +32,16 @@ void *module_alloc(unsigned long size) { + gfp_t gfp_mask = GFP_KERNEL; void *p; + /* Silence the initial allocation */ + if (IS_ENABLED(CONFIG_ARM64_MODULE_PLTS)) + gfp_mask |= __GFP_NOWARN; + p = __vmalloc_node_range(size, MODULE_ALIGN, module_alloc_base, module_alloc_base + MODULES_VSIZE, - GFP_KERNEL, PAGE_KERNEL_EXEC, 0, + gfp_mask, PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE, __builtin_return_address(0)); if (!p && IS_ENABLED(CONFIG_ARM64_MODULE_PLTS) && diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c index d4d6ae02cd55..0805b44f986a 100644 --- a/arch/arm64/kernel/traps.c +++ b/arch/arm64/kernel/traps.c @@ -443,7 +443,7 @@ int cpu_enable_cache_maint_trap(void *__unused) } #define __user_cache_maint(insn, address, res) \ - if (untagged_addr(address) >= user_addr_max()) { \ + if (address >= user_addr_max()) { \ res = -EFAULT; \ } else { \ uaccess_ttbr0_enable(); \ @@ -469,7 +469,7 @@ static void user_cache_maint_handler(unsigned int esr, struct pt_regs *regs) int crm = (esr & ESR_ELx_SYS64_ISS_CRM_MASK) >> ESR_ELx_SYS64_ISS_CRM_SHIFT; int ret = 0; - address = pt_regs_read_reg(regs, rt); + address = untagged_addr(pt_regs_read_reg(regs, rt)); switch (crm) { case ESR_ELx_SYS64_ISS_CRM_DC_CVAU: /* DC CVAU, gets promoted */ diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 1dda6d8a200a..194c22eccb9d 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -521,7 +521,7 @@ overflow: } } - if (printk_ratelimit()) + if (!(gfp_mask & __GFP_NOWARN) && printk_ratelimit()) pr_warn("vmap allocation for size %lu failed: use vmalloc= to increase size\n", size); kfree(va);