riscv: avoid kernel hangs when trapped in BUG() (8b04825e) · Commits · 戴 / test

When the CONFIG_GENERIC_BUG is disabled by disabling CONFIG_BUG, if a kernel thread is trapped by BUG(), the whole system will be in the loop that infinitely handles the ebreak exception instead of entering the die function. To fix this problem, the do_trap_break() will always call the die() to deal with the break exception as the type of break is BUG_TRAP_TYPE_BUG. Signed-off-by:

Vincent Chen <vincent.chen@sifive.com> Reviewed-by:

Christoph Hellwig <hch@lst.de> Signed-off-by:

Paul Walmsley <paul.walmsley@sifive.com>

arch/riscv/kernel/traps.c

+3 −3

Original line number	Original line	Diff line number	Diff line
	@@ -124,23 +124,23 @@ static inline unsigned long get_break_insn_length(unsigned long pc)

	asmlinkage void do_trap_break(struct pt_regs *regs)		asmlinkage void do_trap_break(struct pt_regs *regs)
	{		{
	#ifdef CONFIG_GENERIC_BUG
	if (!user_mode(regs)) {		if (!user_mode(regs)) {
	enum bug_trap_type type;		enum bug_trap_type type;

	type = report_bug(regs->sepc, regs);		type = report_bug(regs->sepc, regs);
	switch (type) {		switch (type) {
			#ifdef CONFIG_GENERIC_BUG
	case BUG_TRAP_TYPE_NONE:		case BUG_TRAP_TYPE_NONE:
	break;		break;
	case BUG_TRAP_TYPE_WARN:		case BUG_TRAP_TYPE_WARN:
	regs->sepc += get_break_insn_length(regs->sepc);		regs->sepc += get_break_insn_length(regs->sepc);
	break;		break;
	case BUG_TRAP_TYPE_BUG:		case BUG_TRAP_TYPE_BUG:
			#endif /* CONFIG_GENERIC_BUG */
			default:
	die(regs, "Kernel BUG");		die(regs, "Kernel BUG");
	}		}
	}		}
	#endif /* CONFIG_GENERIC_BUG */

	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)(regs->sepc));		force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)(regs->sepc));
	}		}

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