diff options
| author | Atish Patra <atish.patra@wdc.com> | 2020-03-17 18:11:43 -0700 |
|---|---|---|
| committer | Palmer Dabbelt <palmerdabbelt@google.com> | 2020-03-31 11:27:50 -0700 |
| commit | cfafe260137418d0265d0df3bb18dc494af2b43e (patch) | |
| tree | 50bde642415f253c2f4bf848fcb5441af43f2c79 /arch/riscv/kernel/head.S | |
| parent | db5a79460315bd12dedee5f964cd72f3a534ecb2 (diff) | |
RISC-V: Add supported for ordered booting method using HSM
Currently, all harts have to jump Linux in RISC-V. This complicates the
multi-stage boot process as every transient stage also has to ensure all
harts enter to that stage and jump to Linux afterwards. It also obstructs
a clean Kexec implementation.
SBI HSM extension provides alternate solutions where only a single hart
need to boot and enter Linux. The booting hart can bring up secondary
harts one by one afterwards.
Add SBI HSM based cpu_ops that implements an ordered booting method in
RISC-V. This change is also backward compatible with older firmware not
implementing HSM extension. If a latest kernel is used with older
firmware, it will continue to use the default spinning booting method.
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Diffstat (limited to 'arch/riscv/kernel/head.S')
| -rw-r--r-- | arch/riscv/kernel/head.S | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S index 173507395a6b..e5115d5e0b3a 100644 --- a/arch/riscv/kernel/head.S +++ b/arch/riscv/kernel/head.S @@ -99,11 +99,37 @@ relocate: ret #endif /* CONFIG_MMU */ #ifdef CONFIG_SMP + .global secondary_start_sbi +secondary_start_sbi: + /* Mask all interrupts */ + csrw CSR_IE, zero + csrw CSR_IP, zero + + /* Load the global pointer */ + .option push + .option norelax + la gp, __global_pointer$ + .option pop + + /* + * Disable FPU to detect illegal usage of + * floating point in kernel space + */ + li t0, SR_FS + csrc CSR_STATUS, t0 + /* Set trap vector to spin forever to help debug */ la a3, .Lsecondary_park csrw CSR_TVEC, a3 slli a3, a0, LGREG + la a4, __cpu_up_stack_pointer + la a5, __cpu_up_task_pointer + add a4, a3, a4 + add a5, a3, a5 + REG_L sp, (a4) + REG_L tp, (a5) + .global secondary_start_common secondary_start_common: |