kernel.git/arch/riscv/kernel/cpu_ops_spinwait.c, branch linux-6.15.y

riscv: prevent pt_regs corruption for secondary idle threads

2024-05-30T16:42:51Z

Top of the kernel thread stack should be reserved for pt_regs. However this is not the case for the idle threads of the secondary boot harts. Their stacks overlap with their pt_regs, so both may get corrupted. Similar issue has been fixed for the primary hart, see c7cdd96eca28 ("riscv: prevent stack corruption by reserving task_pt_regs(p) early"). However that fix was not propagated to the secondary harts. The problem has been noticed in some CPU hotplug tests with V enabled. The function smp_callin stored several registers on stack, corrupting top of pt_regs structure including status field. As a result, kernel attempted to save or restore inexistent V context. Fixes: 9a2451f18663 ("RISC-V: Avoid using per cpu array for ordered booting") Fixes: 2875fe056156 ("RISC-V: Add cpu_ops and modify default booting method") Signed-off-by: Sergey Matyukevich Reviewed-by: Alexandre Ghiti Link: https://lore.kernel.org/r/20240523084327.2013211-1-geomatsi@gmail.com Signed-off-by: Palmer Dabbelt

riscv: Remove unused members from struct cpu_operations

2024-01-04T23:03:06Z

name is not used anywhere at all. cpu_prepare and cpu_disable do nothing and always return 0 if implemented. Signed-off-by: Samuel Holland Reviewed-by: Conor Dooley Link: https://lore.kernel.org/r/20231121234736.3489608-3-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt

RISC-V: cpu_ops_spinwait.c should include head.h

2022-08-11T20:24:16Z

Running sparse shows cpu_ops_spinwait.c is missing two definitions found in head.h, so include it to stop the following warnings: arch/riscv/kernel/cpu_ops_spinwait.c:15:6: warning: symbol '__cpu_spinwait_stack_pointer' was not declared. Should it be static? arch/riscv/kernel/cpu_ops_spinwait.c:16:6: warning: symbol '__cpu_spinwait_task_pointer' was not declared. Should it be static? Signed-off-by: Ben Dooks Link: https://lore.kernel.org/r/20220713215306.94675-1-ben.dooks@sifive.com Fixes: c78f94f35cf6 ("RISC-V: Use __cpu_up_stack/task_pointer only for spinwait method") Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt

riscv: spinwait: Fix hartid variable type

2022-07-19T23:39:03Z

The hartid variable is of type int but compared with ULONG_MAX(INVALID_HARTID). This issue is fixed by changing the hartid variable type to unsigned long. Fixes: c78f94f35cf6 ("RISC-V: Use __cpu_up_stack/task_pointer only for spinwait method") Signed-off-by: Sunil V L Reviewed-by: Atish Patra Link: https://lore.kernel.org/r/20220527051743.2829940-3-sunilvl@ventanamicro.com Signed-off-by: Palmer Dabbelt

RISC-V: Use __cpu_up_stack/task_pointer only for spinwait method

2022-01-20T17:27:08Z

The __cpu_up_stack/task_pointer array is only used for spinwait method now. The per cpu array based lookup is also fragile for platforms with discontiguous/sparse hartids. The spinwait method is only used for M-mode Linux or older firmwares without SBI HSM extension. For general Linux systems, ordered booting method is preferred anyways to support cpu hotplug and kexec. Make sure that __cpu_up_stack/task_pointer is only used for spinwait method. Take this opportunity to rename it to __cpu_spinwait_stack/task_pointer to emphasize the purpose as well. Reviewed-by: Anup Patel Signed-off-by: Atish Patra Signed-off-by: Palmer Dabbelt

RISC-V: Add cpu_ops and modify default booting method

2020-03-31T18:25:56Z

Currently, all non-booting harts start booting after the booting hart updates the per-hart stack pointer. This is done in a way that, it's difficult to implement any other booting method without breaking the backward compatibility. Define a cpu_ops method that allows to introduce other booting methods in future. Modify the current booting method to be compatible with cpu_ops. Signed-off-by: Atish Patra Reviewed-by: Anup Patel Signed-off-by: Palmer Dabbelt