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riscv: avoid kernel hangs when trapped in BUG()

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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>
This commit is contained in:
Vincent Chen 2019-09-23 08:45:14 +08:00 committed by Paul Walmsley
parent da0c9ea146
commit 8b04825ed2
1 changed files with 3 additions and 3 deletions
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6
arch/riscv/kernel/traps.c
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@ -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));
} }