Merge tag 'spi-nor/for-5.5' into mtd/next

SPI NOR core changes:
- introduce 'struct spi_nor_controller_ops',
- clean the Register Operations methods,
- use dev_dbg insted of dev_err for low level info,
- fix retlen handling in sst_write(),
- fix silent truncations in spi_nor_read and spi_nor_read_raw(),
- fix the clearing of QE bit on lock()/unlock(),
- rework the disabling of the block write protection,
- rework the Quad Enable methods,
- make sure nor->spimem and nor->controller_ops are mutually exclusive,
- set default Quad Enable method for ISSI flashes,
- add support for few flashes.

SPI NOR controller drivers changes:
- intel-spi:
	- support chips without software sequencer,
	- add support for Intel Cannon Lake and Intel Comet Lake-H flashes.

1 files changed, 33 insertions, 17 deletions

diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c
index a47462def04b..71f788cd2b18 100644
--- a/arch/arm64/kernel/process.c
+++ b/arch/arm64/kernel/process.c
@@ -17,6 +17,7 @@
 #include <linux/sched/task.h>
 #include <linux/sched/task_stack.h>
 #include <linux/kernel.h>
+#include <linux/lockdep.h>
 #include <linux/mm.h>
 #include <linux/stddef.h>
 #include <linux/sysctl.h>
@@ -44,6 +45,7 @@
 #include <asm/alternative.h>
 #include <asm/arch_gicv3.h>
 #include <asm/compat.h>
+#include <asm/cpufeature.h>
 #include <asm/cacheflush.h>
 #include <asm/exec.h>
 #include <asm/fpsimd.h>
@@ -332,22 +334,27 @@ void arch_release_task_struct(struct task_struct *tsk)
 	fpsimd_release_task(tsk);
 }
 
-/*
- * src and dst may temporarily have aliased sve_state after task_struct
- * is copied.  We cannot fix this properly here, because src may have
- * live SVE state and dst's thread_info may not exist yet, so tweaking
- * either src's or dst's TIF_SVE is not safe.
- *
- * The unaliasing is done in copy_thread() instead.  This works because
- * dst is not schedulable or traceable until both of these functions
- * have been called.
- */
 int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 {
 	if (current->mm)
 		fpsimd_preserve_current_state();
 	*dst = *src;
 
+	/* We rely on the above assignment to initialize dst's thread_flags: */
+	BUILD_BUG_ON(!IS_ENABLED(CONFIG_THREAD_INFO_IN_TASK));
+
+	/*
+	 * Detach src's sve_state (if any) from dst so that it does not
+	 * get erroneously used or freed prematurely.  dst's sve_state
+	 * will be allocated on demand later on if dst uses SVE.
+	 * For consistency, also clear TIF_SVE here: this could be done
+	 * later in copy_process(), but to avoid tripping up future
+	 * maintainers it is best not to leave TIF_SVE and sve_state in
+	 * an inconsistent state, even temporarily.
+	 */
+	dst->thread.sve_state = NULL;
+	clear_tsk_thread_flag(dst, TIF_SVE);
+
 	return 0;
 }
 
@@ -361,13 +368,6 @@ int copy_thread(unsigned long clone_flags, unsigned long stack_start,
 	memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));
 
 	/*
-	 * Unalias p->thread.sve_state (if any) from the parent task
-	 * and disable discard SVE state for p:
-	 */
-	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.
@@ -633,3 +633,19 @@ static int __init tagged_addr_init(void)
 
 core_initcall(tagged_addr_init);
 #endif	/* CONFIG_ARM64_TAGGED_ADDR_ABI */
+
+asmlinkage void __sched arm64_preempt_schedule_irq(void)
+{
+	lockdep_assert_irqs_disabled();
+
+	/*
+	 * Preempting a task from an IRQ means we leave copies of PSTATE
+	 * on the stack. cpufeature's enable calls may modify PSTATE, but
+	 * resuming one of these preempted tasks would undo those changes.
+	 *
+	 * Only allow a task to be preempted once cpufeatures have been
+	 * enabled.
+	 */
+	if (static_branch_likely(&arm64_const_caps_ready))
+		preempt_schedule_irq();
+}