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| author | Sergey Matyukevich <sergey.matyukevich@syntacore.com> | 2024-05-23 10:43:23 +0200 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2024-05-30 18:42:51 +0200 |
| commit | a638b0461b58aa3205cd9d5f14d6f703d795b4af (patch) | |
| tree | ce68ca8619c3314e4d30c0e2e0449cd474c2310d | |
| parent | Linux 6.10-rc1 (diff) | |
| download | linux-a638b0461b58aa3205cd9d5f14d6f703d795b4af.tar.xz linux-a638b0461b58aa3205cd9d5f14d6f703d795b4af.zip | |
riscv: prevent pt_regs corruption for secondary idle threads
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 <sergey.matyukevich@syntacore.com>
Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20240523084327.2013211-1-geomatsi@gmail.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
| -rw-r--r-- | arch/riscv/kernel/cpu_ops_sbi.c | 2 | ||||
| -rw-r--r-- | arch/riscv/kernel/cpu_ops_spinwait.c | 3 |
2 files changed, 2 insertions, 3 deletions
diff --git a/arch/riscv/kernel/cpu_ops_sbi.c b/arch/riscv/kernel/cpu_ops_sbi.c index 1cc7df740edd..e6fbaaf54956 100644 --- a/arch/riscv/kernel/cpu_ops_sbi.c +++ b/arch/riscv/kernel/cpu_ops_sbi.c @@ -72,7 +72,7 @@ static int sbi_cpu_start(unsigned int cpuid, struct task_struct *tidle) /* Make sure tidle is updated */ smp_mb(); bdata->task_ptr = tidle; - bdata->stack_ptr = task_stack_page(tidle) + THREAD_SIZE; + bdata->stack_ptr = task_pt_regs(tidle); /* Make sure boot data is updated */ smp_mb(); hsm_data = __pa(bdata); diff --git a/arch/riscv/kernel/cpu_ops_spinwait.c b/arch/riscv/kernel/cpu_ops_spinwait.c index 613872b0a21a..24869eb88908 100644 --- a/arch/riscv/kernel/cpu_ops_spinwait.c +++ b/arch/riscv/kernel/cpu_ops_spinwait.c @@ -34,8 +34,7 @@ static void cpu_update_secondary_bootdata(unsigned int cpuid, /* Make sure tidle is updated */ smp_mb(); - WRITE_ONCE(__cpu_spinwait_stack_pointer[hartid], - task_stack_page(tidle) + THREAD_SIZE); + WRITE_ONCE(__cpu_spinwait_stack_pointer[hartid], task_pt_regs(tidle)); WRITE_ONCE(__cpu_spinwait_task_pointer[hartid], tidle); } |