6.15-stable review patch. If anyone has any objections, please let me know.
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From: Nam Cao namcao@linutronix.de
[ Upstream commit 969f028bf2c40573ef18061f702ede3ebfe12b42 ]
force_sig_fault() takes a spinlock, which is a sleeping lock with CONFIG_PREEMPT_RT=y. However, exception handling calls force_sig_fault() with interrupt disabled, causing a sleeping in atomic context warning.
This can be reproduced using userspace programs such as: int main() { asm ("ebreak"); } or int main() { asm ("unimp"); }
There is no reason that interrupt must be disabled while handling exceptions from userspace.
Enable interrupt while handling user exceptions. This also has the added benefit of avoiding unnecessary delays in interrupt handling.
Fixes: f0bddf50586d ("riscv: entry: Convert to generic entry") Suggested-by: Sebastian Andrzej Siewior bigeasy@linutronix.de Signed-off-by: Nam Cao namcao@linutronix.de Reviewed-by: Alexandre Ghiti alexghiti@rivosinc.com Link: https://lore.kernel.org/r/20250625085630.3649485-1-namcao@linutronix.de Signed-off-by: Palmer Dabbelt palmer@dabbelt.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/riscv/kernel/traps.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index 9c83848797a78..80230de167def 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -6,6 +6,7 @@ #include <linux/cpu.h> #include <linux/kernel.h> #include <linux/init.h> +#include <linux/irqflags.h> #include <linux/randomize_kstack.h> #include <linux/sched.h> #include <linux/sched/debug.h> @@ -151,7 +152,9 @@ asmlinkage __visible __trap_section void name(struct pt_regs *regs) \ { \ if (user_mode(regs)) { \ irqentry_enter_from_user_mode(regs); \ + local_irq_enable(); \ do_trap_error(regs, signo, code, regs->epc, "Oops - " str); \ + local_irq_disable(); \ irqentry_exit_to_user_mode(regs); \ } else { \ irqentry_state_t state = irqentry_nmi_enter(regs); \ @@ -173,17 +176,14 @@ asmlinkage __visible __trap_section void do_trap_insn_illegal(struct pt_regs *re
if (user_mode(regs)) { irqentry_enter_from_user_mode(regs); - local_irq_enable();
handled = riscv_v_first_use_handler(regs); - - local_irq_disable(); - if (!handled) do_trap_error(regs, SIGILL, ILL_ILLOPC, regs->epc, "Oops - illegal instruction");
+ local_irq_disable(); irqentry_exit_to_user_mode(regs); } else { irqentry_state_t state = irqentry_nmi_enter(regs); @@ -308,9 +308,11 @@ asmlinkage __visible __trap_section void do_trap_break(struct pt_regs *regs) { if (user_mode(regs)) { irqentry_enter_from_user_mode(regs); + local_irq_enable();
handle_break(regs);
+ local_irq_disable(); irqentry_exit_to_user_mode(regs); } else { irqentry_state_t state = irqentry_nmi_enter(regs);