diff options
Diffstat (limited to 'arch/riscv/kernel')
| -rw-r--r-- | arch/riscv/kernel/entry.S | 21 | ||||
| -rw-r--r-- | arch/riscv/kernel/traps.c | 14 |
2 files changed, 27 insertions, 8 deletions
diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 9b60878a4469..2a82e0a5af46 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -98,7 +98,26 @@ _save_context: */ .macro RESTORE_ALL REG_L a0, PT_SSTATUS(sp) - REG_L a2, PT_SEPC(sp) + /* + * The current load reservation is effectively part of the processor's + * state, in the sense that load reservations cannot be shared between + * different hart contexts. We can't actually save and restore a load + * reservation, so instead here we clear any existing reservation -- + * it's always legal for implementations to clear load reservations at + * any point (as long as the forward progress guarantee is kept, but + * we'll ignore that here). + * + * Dangling load reservations can be the result of taking a trap in the + * middle of an LR/SC sequence, but can also be the result of a taken + * forward branch around an SC -- which is how we implement CAS. As a + * result we need to clear reservations between the last CAS and the + * jump back to the new context. While it is unlikely the store + * completes, implementations are allowed to expand reservations to be + * arbitrarily large. + */ + REG_L a2, PT_SEPC(sp) + REG_SC x0, a2, PT_SEPC(sp) + csrw CSR_SSTATUS, a0 csrw CSR_SEPC, a2 diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index 424eb72d56b1..93742df9067f 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -124,24 +124,24 @@ static inline unsigned long get_break_insn_length(unsigned long pc) asmlinkage void do_trap_break(struct pt_regs *regs) { -#ifdef CONFIG_GENERIC_BUG if (!user_mode(regs)) { enum bug_trap_type type; type = report_bug(regs->sepc, regs); switch (type) { - case BUG_TRAP_TYPE_NONE: - break; +#ifdef CONFIG_GENERIC_BUG case BUG_TRAP_TYPE_WARN: regs->sepc += get_break_insn_length(regs->sepc); - break; + return; case BUG_TRAP_TYPE_BUG: +#endif /* CONFIG_GENERIC_BUG */ + default: die(regs, "Kernel BUG"); } + } else { + force_sig_fault(SIGTRAP, TRAP_BRKPT, + (void __user *)(regs->sepc)); } -#endif /* CONFIG_GENERIC_BUG */ - - force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)(regs->sepc)); } #ifdef CONFIG_GENERIC_BUG |