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authorLinus Torvalds <torvalds@linux-foundation.org>2022-05-20 08:09:00 -1000
committerLinus Torvalds <torvalds@linux-foundation.org>2022-05-20 08:09:00 -1000
commita956f4e281fe548a541a4970a6e8a0ec283b0d6d (patch)
tree8d282eeba32305c2492dc8fba16b64cad6c87404 /arch/arm64
parent3d7285a335edaf23b699e87c528cf0b0070e3293 (diff)
parent1d0cb4c8864addc362bae98e8ffa5500c87e1227 (diff)
Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fixes from Will Deacon: "Three arm64 fixes for -rc8/final. The MTE and stolen time fixes have been doing the rounds for a little while, but review and testing feedback was ongoing until earlier this week. The kexec fix showed up on Monday and addresses a failure observed under Qemu. Summary: - Add missing write barrier to publish MTE tags before a pte update - Fix kexec relocation clobbering its own data structures - Fix stolen time crash if a timer IRQ fires during CPU hotplug" * tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: arm64: mte: Ensure the cleared tags are visible before setting the PTE arm64: kexec: load from kimage prior to clobbering arm64: paravirt: Use RCU read locks to guard stolen_time
Diffstat (limited to 'arch/arm64')
-rw-r--r--arch/arm64/kernel/mte.c3
-rw-r--r--arch/arm64/kernel/paravirt.c29
-rw-r--r--arch/arm64/kernel/relocate_kernel.S22
3 files changed, 39 insertions, 15 deletions
diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c
index 78b3e0f8e997..d502703e8373 100644
--- a/arch/arm64/kernel/mte.c
+++ b/arch/arm64/kernel/mte.c
@@ -76,6 +76,9 @@ void mte_sync_tags(pte_t old_pte, pte_t pte)
mte_sync_page_tags(page, old_pte, check_swap,
pte_is_tagged);
}
+
+ /* ensure the tags are visible before the PTE is set */
+ smp_wmb();
}
int memcmp_pages(struct page *page1, struct page *page2)
diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
index 75fed4460407..57c7c211f8c7 100644
--- a/arch/arm64/kernel/paravirt.c
+++ b/arch/arm64/kernel/paravirt.c
@@ -35,7 +35,7 @@ static u64 native_steal_clock(int cpu)
DEFINE_STATIC_CALL(pv_steal_clock, native_steal_clock);
struct pv_time_stolen_time_region {
- struct pvclock_vcpu_stolen_time *kaddr;
+ struct pvclock_vcpu_stolen_time __rcu *kaddr;
};
static DEFINE_PER_CPU(struct pv_time_stolen_time_region, stolen_time_region);
@@ -52,7 +52,9 @@ early_param("no-steal-acc", parse_no_stealacc);
/* return stolen time in ns by asking the hypervisor */
static u64 para_steal_clock(int cpu)
{
+ struct pvclock_vcpu_stolen_time *kaddr = NULL;
struct pv_time_stolen_time_region *reg;
+ u64 ret = 0;
reg = per_cpu_ptr(&stolen_time_region, cpu);
@@ -61,28 +63,37 @@ static u64 para_steal_clock(int cpu)
* online notification callback runs. Until the callback
* has run we just return zero.
*/
- if (!reg->kaddr)
+ rcu_read_lock();
+ kaddr = rcu_dereference(reg->kaddr);
+ if (!kaddr) {
+ rcu_read_unlock();
return 0;
+ }
- return le64_to_cpu(READ_ONCE(reg->kaddr->stolen_time));
+ ret = le64_to_cpu(READ_ONCE(kaddr->stolen_time));
+ rcu_read_unlock();
+ return ret;
}
static int stolen_time_cpu_down_prepare(unsigned int cpu)
{
+ struct pvclock_vcpu_stolen_time *kaddr = NULL;
struct pv_time_stolen_time_region *reg;
reg = this_cpu_ptr(&stolen_time_region);
if (!reg->kaddr)
return 0;
- memunmap(reg->kaddr);
- memset(reg, 0, sizeof(*reg));
+ kaddr = rcu_replace_pointer(reg->kaddr, NULL, true);
+ synchronize_rcu();
+ memunmap(kaddr);
return 0;
}
static int stolen_time_cpu_online(unsigned int cpu)
{
+ struct pvclock_vcpu_stolen_time *kaddr = NULL;
struct pv_time_stolen_time_region *reg;
struct arm_smccc_res res;
@@ -93,17 +104,19 @@ static int stolen_time_cpu_online(unsigned int cpu)
if (res.a0 == SMCCC_RET_NOT_SUPPORTED)
return -EINVAL;
- reg->kaddr = memremap(res.a0,
+ kaddr = memremap(res.a0,
sizeof(struct pvclock_vcpu_stolen_time),
MEMREMAP_WB);
+ rcu_assign_pointer(reg->kaddr, kaddr);
+
if (!reg->kaddr) {
pr_warn("Failed to map stolen time data structure\n");
return -ENOMEM;
}
- if (le32_to_cpu(reg->kaddr->revision) != 0 ||
- le32_to_cpu(reg->kaddr->attributes) != 0) {
+ if (le32_to_cpu(kaddr->revision) != 0 ||
+ le32_to_cpu(kaddr->attributes) != 0) {
pr_warn_once("Unexpected revision or attributes in stolen time data\n");
return -ENXIO;
}
diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
index f0a3df9e18a3..413f899e4ac6 100644
--- a/arch/arm64/kernel/relocate_kernel.S
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -37,6 +37,15 @@
* safe memory that has been set up to be preserved during the copy operation.
*/
SYM_CODE_START(arm64_relocate_new_kernel)
+ /*
+ * The kimage structure isn't allocated specially and may be clobbered
+ * during relocation. We must load any values we need from it prior to
+ * any relocation occurring.
+ */
+ ldr x28, [x0, #KIMAGE_START]
+ ldr x27, [x0, #KIMAGE_ARCH_EL2_VECTORS]
+ ldr x26, [x0, #KIMAGE_ARCH_DTB_MEM]
+
/* Setup the list loop variables. */
ldr x18, [x0, #KIMAGE_ARCH_ZERO_PAGE] /* x18 = zero page for BBM */
ldr x17, [x0, #KIMAGE_ARCH_TTBR1] /* x17 = linear map copy */
@@ -72,21 +81,20 @@ SYM_CODE_START(arm64_relocate_new_kernel)
ic iallu
dsb nsh
isb
- ldr x4, [x0, #KIMAGE_START] /* relocation start */
- ldr x1, [x0, #KIMAGE_ARCH_EL2_VECTORS] /* relocation start */
- ldr x0, [x0, #KIMAGE_ARCH_DTB_MEM] /* dtb address */
turn_off_mmu x12, x13
/* Start new image. */
- cbz x1, .Lel1
- mov x1, x4 /* relocation start */
- mov x2, x0 /* dtb address */
+ cbz x27, .Lel1
+ mov x1, x28 /* kernel entry point */
+ mov x2, x26 /* dtb address */
mov x3, xzr
mov x4, xzr
mov x0, #HVC_SOFT_RESTART
hvc #0 /* Jumps from el2 */
.Lel1:
+ mov x0, x26 /* dtb address */
+ mov x1, xzr
mov x2, xzr
mov x3, xzr
- br x4 /* Jumps from el1 */
+ br x28 /* Jumps from el1 */
SYM_CODE_END(arm64_relocate_new_kernel)