diff options
| author | Andy Chiu <andy.chiu@sifive.com> | 2025-04-08 02:08:31 +0800 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@dabbelt.com> | 2025-06-05 11:09:27 -0700 |
| commit | d1049fc0de81bca3abbb35e8d4b8794170498b78 (patch) | |
| tree | e02e3e470c90a1b785db85bcbc08669acb21bcfe /arch/riscv/include/asm/processor.h | |
| parent | 5aa4ef95588456df5a5563dd23892827f97fb14f (diff) | |
riscv: vector: Support calling schedule() for preemptible Vector
Each function entry implies a call to ftrace infrastructure. And it may
call into schedule in some cases. So, it is possible for preemptible
kernel-mode Vector to implicitly call into schedule. Since all V-regs
are caller-saved, it is possible to drop all V context when a thread
voluntarily call schedule(). Besides, we currently don't pass argument
through vector register, so we don't have to save/restore V-regs in
ftrace trampoline.
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Link: https://lore.kernel.org/r/20250407180838.42877-7-andybnac@gmail.com
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Palmer Dabbelt <palmer@dabbelt.com>
Diffstat (limited to 'arch/riscv/include/asm/processor.h')
| -rw-r--r-- | arch/riscv/include/asm/processor.h | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h index 5f56eb9d114a..9c1cc716b891 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -79,6 +79,10 @@ struct pt_regs; * Thus, the task does not own preempt_v. Any use of Vector will have to * save preempt_v, if dirty, and fallback to non-preemptible kernel-mode * Vector. + * - bit 29: The thread voluntarily calls schedule() while holding an active + * preempt_v. All preempt_v context should be dropped in such case because + * V-regs are caller-saved. Only sstatus.VS=ON is persisted across a + * schedule() call. * - bit 30: The in-kernel preempt_v context is saved, and requries to be * restored when returning to the context that owns the preempt_v. * - bit 31: The in-kernel preempt_v context is dirty, as signaled by the @@ -93,6 +97,7 @@ struct pt_regs; #define RISCV_PREEMPT_V 0x00000100 #define RISCV_PREEMPT_V_DIRTY 0x80000000 #define RISCV_PREEMPT_V_NEED_RESTORE 0x40000000 +#define RISCV_PREEMPT_V_IN_SCHEDULE 0x20000000 /* CPU-specific state of a task */ struct thread_struct { |