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-rw-r--r--Documentation/arm64/tagged-pointers.txt62
-rw-r--r--arch/arm/kernel/module.c11
-rw-r--r--arch/arm64/include/asm/asm-uaccess.h9
-rw-r--r--arch/arm64/include/asm/atomic_lse.h4
-rw-r--r--arch/arm64/include/asm/barrier.h20
-rw-r--r--arch/arm64/include/asm/cmpxchg.h2
-rw-r--r--arch/arm64/include/asm/uaccess.h13
-rw-r--r--arch/arm64/kernel/armv8_deprecated.c3
-rw-r--r--arch/arm64/kernel/entry.S5
-rw-r--r--arch/arm64/kernel/hw_breakpoint.c3
-rw-r--r--arch/arm64/kernel/module.c7
-rw-r--r--arch/arm64/kernel/traps.c4
-rw-r--r--mm/vmalloc.c2
13 files changed, 107 insertions, 38 deletions
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 <asm/traps.h>
#include <asm/cputype.h>
#include <asm/system_misc.h>
+#include <asm/uaccess.h>
/* 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=<size> to increase size\n",
size);
kfree(va);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-11 23:39:08 +0000