diff options
| author | Andy Chiu <andy.chiu@sifive.com> | 2024-01-15 05:59:29 +0000 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2024-01-16 07:14:02 -0800 |
| commit | 2080ff9493072a94e42b1856d59f5f1bffb761b7 (patch) | |
| tree | 4e79b0581b55d4ce2bff3e05c1d641183e556741 /arch/riscv/kernel/entry.S | |
| parent | bd446f5df5afab212917f6732ba6442a5e8de85e (diff) | |
riscv: vector: allow kernel-mode Vector with preemption
Add kernel_vstate to keep track of kernel-mode Vector registers when
trap introduced context switch happens. Also, provide riscv_v_flags to
let context save/restore routine track context status. Context tracking
happens whenever the core starts its in-kernel Vector executions. An
active (dirty) kernel task's V contexts will be saved to memory whenever
a trap-introduced context switch happens. Or, when a softirq, which
happens to nest on top of it, uses Vector. Context retoring happens when
the execution transfer back to the original Kernel context where it
first enable preempt_v.
Also, provide a config CONFIG_RISCV_ISA_V_PREEMPTIVE to give users an
option to disable preemptible kernel-mode Vector at build time. Users
with constraint memory may want to disable this config as preemptible
kernel-mode Vector needs extra space for tracking of per thread's
kernel-mode V context. Or, users might as well want to disable it if all
kernel-mode Vector code is time sensitive and cannot tolerate context
switch overhead.
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Tested-by: Björn Töpel <bjorn@rivosinc.com>
Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20240115055929.4736-11-andy.chiu@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'arch/riscv/kernel/entry.S')
| -rw-r--r-- | arch/riscv/kernel/entry.S | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 54ca4564a926..9d1a305d5508 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -83,6 +83,10 @@ SYM_CODE_START(handle_exception) /* Load the kernel shadow call stack pointer if coming from userspace */ scs_load_current_if_task_changed s5 +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE + move a0, sp + call riscv_v_context_nesting_start +#endif move a0, sp /* pt_regs */ la ra, ret_from_exception @@ -138,6 +142,10 @@ SYM_CODE_START_NOALIGN(ret_from_exception) */ csrw CSR_SCRATCH, tp 1: +#ifdef CONFIG_RISCV_ISA_V_PREEMPTIVE + move a0, sp + call riscv_v_context_nesting_end +#endif REG_L a0, PT_STATUS(sp) /* * The current load reservation is effectively part of the processor's |