diff --git a/arch/arm64/include/asm/efi.h b/arch/arm64/include/asm/efi.h
index 650344d01124971d98819116b7e657c7fce7c6f4..c4cd5081d78bc4b66e34f3c283d9b1f6ba48518c 100644
--- a/arch/arm64/include/asm/efi.h
+++ b/arch/arm64/include/asm/efi.h
@@ -132,11 +132,9 @@ static inline void efi_set_pgd(struct mm_struct *mm)
* Defer the switch to the current thread's TTBR0_EL1
* until uaccess_enable(). Restore the current
* thread's saved ttbr0 corresponding to its active_mm
- * (if different from init_mm).
*/
cpu_set_reserved_ttbr0();
- if (current->active_mm != &init_mm)
- update_saved_ttbr0(current, current->active_mm);
+ update_saved_ttbr0(current, current->active_mm);
}
}
}
diff --git a/arch/arm64/include/asm/mmu_context.h b/arch/arm64/include/asm/mmu_context.h
index 3257895a9b5e413c7c69c9d3cdb2fa23ec030592..9d155fa9a50791af293916cfdc1ede087f850c6d 100644
--- a/arch/arm64/include/asm/mmu_context.h
+++ b/arch/arm64/include/asm/mmu_context.h
@@ -156,29 +156,21 @@ void check_and_switch_context(struct mm_struct *mm, unsigned int cpu);
#define init_new_context(tsk,mm) ({ atomic64_set(&(mm)->context.id, 0); 0; })
-/*
- * This is called when "tsk" is about to enter lazy TLB mode.
- *
- * mm: describes the currently active mm context
- * tsk: task which is entering lazy tlb
- * cpu: cpu number which is entering lazy tlb
- *
- * tsk->mm will be NULL
- */
-static inline void
-enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
-{
-}
-
#ifdef CONFIG_ARM64_SW_TTBR0_PAN
static inline void update_saved_ttbr0(struct task_struct *tsk,
struct mm_struct *mm)
{
- if (system_uses_ttbr0_pan()) {
- BUG_ON(mm->pgd == swapper_pg_dir);
- task_thread_info(tsk)->ttbr0 =
- virt_to_phys(mm->pgd) | ASID(mm) << 48;
- }
+ u64 ttbr;
+
+ if (!system_uses_ttbr0_pan())
+ return;
+
+ if (mm == &init_mm)
+ ttbr = __pa_symbol(empty_zero_page);
+ else
+ ttbr = virt_to_phys(mm->pgd) | ASID(mm) << 48;
+
+ task_thread_info(tsk)->ttbr0 = ttbr;
}
#else
static inline void update_saved_ttbr0(struct task_struct *tsk,
@@ -187,6 +179,16 @@ static inline void update_saved_ttbr0(struct task_struct *tsk,
}
#endif
+static inline void
+enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk)
+{
+ /*
+ * We don't actually care about the ttbr0 mapping, so point it at the
+ * zero page.
+ */
+ update_saved_ttbr0(tsk, &init_mm);
+}
+
static inline void __switch_mm(struct mm_struct *next)
{
unsigned int cpu = smp_processor_id();
@@ -214,11 +216,9 @@ switch_mm(struct mm_struct *prev, struct mm_struct *next,
* Update the saved TTBR0_EL1 of the scheduled-in task as the previous
* value may have not been initialised yet (activate_mm caller) or the
* ASID has changed since the last run (following the context switch
- * of another thread of the same process). Avoid setting the reserved
- * TTBR0_EL1 to swapper_pg_dir (init_mm; e.g. via idle_task_exit).
+ * of another thread of the same process).
*/
- if (next != &init_mm)
- update_saved_ttbr0(tsk, next);
+ update_saved_ttbr0(tsk, next);
}
#define deactivate_mm(tsk,mm) do { } while (0)
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 5084e699447a4d011742ad964448203c1d93337a..540a1e010eb519a6223e091d5f9f00b716fc2c7b 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -114,7 +114,12 @@
* returned from the 2nd syscall yet, TIF_FOREIGN_FPSTATE is still set so
* whatever is in the FPSIMD registers is not saved to memory, but discarded.
*/
-static DEFINE_PER_CPU(struct fpsimd_state *, fpsimd_last_state);
+struct fpsimd_last_state_struct {
+ struct fpsimd_state *st;
+ bool sve_in_use;
+};
+
+static DEFINE_PER_CPU(struct fpsimd_last_state_struct, fpsimd_last_state);
/* Default VL for tasks that don't set it explicitly: */
static int sve_default_vl = -1;
@@ -905,7 +910,7 @@ void fpsimd_thread_switch(struct task_struct *next)
*/
struct fpsimd_state *st = &next->thread.fpsimd_state;
- if (__this_cpu_read(fpsimd_last_state) == st
+ if (__this_cpu_read(fpsimd_last_state.st) == st
&& st->cpu == smp_processor_id())
clear_tsk_thread_flag(next, TIF_FOREIGN_FPSTATE);
else
@@ -991,6 +996,21 @@ void fpsimd_signal_preserve_current_state(void)
sve_to_fpsimd(current);
}
+/*
+ * Associate current's FPSIMD context with this cpu
+ * Preemption must be disabled when calling this function.
+ */
+static void fpsimd_bind_to_cpu(void)
+{
+ struct fpsimd_last_state_struct *last =
+ this_cpu_ptr(&fpsimd_last_state);
+ struct fpsimd_state *st = ¤t->thread.fpsimd_state;
+
+ last->st = st;
+ last->sve_in_use = test_thread_flag(TIF_SVE);
+ st->cpu = smp_processor_id();
+}
+
/*
* Load the userland FPSIMD state of 'current' from memory, but only if the
* FPSIMD state already held in the registers is /not/ the most recent FPSIMD
@@ -1004,11 +1024,8 @@ void fpsimd_restore_current_state(void)
local_bh_disable();
if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
- struct fpsimd_state *st = ¤t->thread.fpsimd_state;
-
task_fpsimd_load();
- __this_cpu_write(fpsimd_last_state, st);
- st->cpu = smp_processor_id();
+ fpsimd_bind_to_cpu();
}
local_bh_enable();
@@ -1032,12 +1049,8 @@ void fpsimd_update_current_state(struct fpsimd_state *state)
task_fpsimd_load();
- if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
- struct fpsimd_state *st = ¤t->thread.fpsimd_state;
-
- __this_cpu_write(fpsimd_last_state, st);
- st->cpu = smp_processor_id();
- }
+ if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE))
+ fpsimd_bind_to_cpu();
local_bh_enable();
}
@@ -1052,7 +1065,7 @@ void fpsimd_flush_task_state(struct task_struct *t)
static inline void fpsimd_flush_cpu_state(void)
{
- __this_cpu_write(fpsimd_last_state, NULL);
+ __this_cpu_write(fpsimd_last_state.st, NULL);
}
/*
@@ -1065,14 +1078,10 @@ static inline void fpsimd_flush_cpu_state(void)
#ifdef CONFIG_ARM64_SVE
void sve_flush_cpu_state(void)
{
- struct fpsimd_state *const fpstate = __this_cpu_read(fpsimd_last_state);
- struct task_struct *tsk;
-
- if (!fpstate)
- return;
+ struct fpsimd_last_state_struct const *last =
+ this_cpu_ptr(&fpsimd_last_state);
- tsk = container_of(fpstate, struct task_struct, thread.fpsimd_state);
- if (test_tsk_thread_flag(tsk, TIF_SVE))
+ if (last->st && last->sve_in_use)
fpsimd_flush_cpu_state();
}
#endif /* CONFIG_ARM64_SVE */
@@ -1267,7 +1276,7 @@ static inline void fpsimd_pm_init(void) { }
#ifdef CONFIG_HOTPLUG_CPU
static int fpsimd_cpu_dead(unsigned int cpu)
{
- per_cpu(fpsimd_last_state, cpu) = NULL;
+ per_cpu(fpsimd_last_state.st, cpu) = NULL;
return 0;
}
diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index b2adcce7bc18e628c924d009ba38190cb1bff951..6b7dcf4310acf6fc04ff40cca4ccd10e27fabec9 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -314,6 +314,15 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
clear_tsk_thread_flag(p, TIF_SVE);
p->thread.sve_state = NULL;
+ /*
+ * In case p was allocated the same task_struct pointer as some
+ * other recently-exited task, make sure p is disassociated from
+ * any cpu that may have run that now-exited task recently.
+ * Otherwise we could erroneously skip reloading the FPSIMD
+ * registers for p.
+ */
+ fpsimd_flush_task_state(p);
+
if (likely(!(p->flags & PF_KTHREAD))) {
*childregs = *current_pt_regs();
childregs->regs[0] = 0;