From: Sergey Matyukevich sergey.matyukevich@syntacore.com
stable inclusion from stable-v6.6.33 commit 3090c06d50eaa91317f84bf3eac4c265e6cb8d44 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IAD6H2
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...
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commit a638b0461b58aa3205cd9d5f14d6f703d795b4af upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Wang Hai wanghai38@huawei.com --- arch/riscv/kernel/cpu_ops_sbi.c | 2 +- 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 efa0f0816634..93cbc38d1805 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 d98d19226b5f..691e0c5366d2 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); }