riscv: add PREEMPT_LAZY support

riscv has switched to GENERIC_ENTRY, so adding PREEMPT_LAZY is as simple
as adding TIF_NEED_RESCHED_LAZY related definitions and enabling
ARCH_HAS_PREEMPT_LAZY.

[bigeasy: Replace old PREEMPT_AUTO bits with new PREEMPT_LAZY ]

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Palmer Dabbelt <palmer@rivosinc.com>
Link: https://lkml.kernel.org/r/20241021151257.102296-4-bigeasy@linutronix.de

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 62545946ecf432df5b41e235ba66438cd3743c06..3516c584806122eb4441f069282bf461af553248 100644 (file)
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -39,6 +39,7 @@ config RISCV
        select ARCH_HAS_MMIOWB
        select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE
        select ARCH_HAS_PMEM_API
+       select ARCH_HAS_PREEMPT_LAZY
        select ARCH_HAS_PREPARE_SYNC_CORE_CMD
        select ARCH_HAS_PTE_DEVMAP if 64BIT && MMU
        select ARCH_HAS_PTE_SPECIAL

diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h
index 9c10fb180f43899042bf4b293aa72b630599df09..f5916a70879a87d9356bb755ca78b4d2e7f65f6e 100644 (file)
--- a/arch/riscv/include/asm/thread_info.h
+++ b/arch/riscv/include/asm/thread_info.h
@@ -107,9 +107,10 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
  * - pending work-to-be-done flags are in lowest half-word
  * - other flags in upper half-word(s)
  */
-#define TIF_NOTIFY_RESUME      1       /* callback before returning to user */
-#define TIF_SIGPENDING         2       /* signal pending */
-#define TIF_NEED_RESCHED       3       /* rescheduling necessary */
+#define TIF_NEED_RESCHED       0       /* rescheduling necessary */
+#define TIF_NEED_RESCHED_LAZY  1       /* Lazy rescheduling needed */
+#define TIF_NOTIFY_RESUME      2       /* callback before returning to user */
+#define TIF_SIGPENDING         3       /* signal pending */
 #define TIF_RESTORE_SIGMASK    4       /* restore signal mask in do_signal() */
 #define TIF_MEMDIE             5       /* is terminating due to OOM killer */
 #define TIF_NOTIFY_SIGNAL      9       /* signal notifications exist */
@@ -117,9 +118,10 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src);
 #define TIF_32BIT              11      /* compat-mode 32bit process */
 #define TIF_RISCV_V_DEFER_RESTORE      12 /* restore Vector before returing to user */
 
+#define _TIF_NEED_RESCHED      (1 << TIF_NEED_RESCHED)
+#define _TIF_NEED_RESCHED_LAZY (1 << TIF_NEED_RESCHED_LAZY)
 #define _TIF_NOTIFY_RESUME     (1 << TIF_NOTIFY_RESUME)
 #define _TIF_SIGPENDING                (1 << TIF_SIGPENDING)
-#define _TIF_NEED_RESCHED      (1 << TIF_NEED_RESCHED)
 #define _TIF_NOTIFY_SIGNAL     (1 << TIF_NOTIFY_SIGNAL)
 #define _TIF_UPROBE            (1 << TIF_UPROBE)
 #define _TIF_RISCV_V_DEFER_RESTORE     (1 << TIF_RISCV_V_DEFER_RESTORE)