6.6-stable review patch. If anyone has any objections, please let me know.
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From: Tiezhu Yang yangtiezhu@loongson.cn
[ Upstream commit cc73cc6bcdb5f959670e3ff9abdc62461452ddff ]
Currently, interrupts need to be disabled before single-step mode is set, it requires that CSR_PRMD_PIE be cleared in save_local_irqflag() which is called by setup_singlestep(), this is reasonable.
But in the first kprobe breakpoint exception, if the irq is enabled at the beginning of do_bp(), it will not be disabled at the end of do_bp() due to the CSR_PRMD_PIE has been cleared in save_local_irqflag(). So for this case, it may corrupt exception context when restoring the exception after do_bp() in handle_bp(), this is not reasonable.
In order to restore exception safely in handle_bp(), it needs to ensure the irq is disabled at the end of do_bp(), so just add a local variable to record the original interrupt status in the parent context, then use it as the check condition to enable and disable irq in do_bp().
While at it, do the similar thing for other do_xyz() exception handlers to make them more robust.
Fixes: 6d4cc40fb5f5 ("LoongArch: Add kprobes support") Suggested-by: Jinyang He hejinyang@loongson.cn Suggested-by: Huacai Chen chenhuacai@loongson.cn Co-developed-by: Tianyang Zhang zhangtianyang@loongson.cn Signed-off-by: Tianyang Zhang zhangtianyang@loongson.cn Signed-off-by: Tiezhu Yang yangtiezhu@loongson.cn Signed-off-by: Huacai Chen chenhuacai@loongson.cn Signed-off-by: Sasha Levin sashal@kernel.org --- arch/loongarch/kernel/traps.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c index d59052c03d9b7..2b4b99b4e6c94 100644 --- a/arch/loongarch/kernel/traps.c +++ b/arch/loongarch/kernel/traps.c @@ -527,9 +527,10 @@ asmlinkage void noinstr do_ale(struct pt_regs *regs) die_if_kernel("Kernel ale access", regs); force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)regs->csr_badvaddr); #else + bool pie = regs_irqs_disabled(regs); unsigned int *pc;
- if (regs->csr_prmd & CSR_PRMD_PIE) + if (!pie) local_irq_enable();
perf_sw_event(PERF_COUNT_SW_ALIGNMENT_FAULTS, 1, regs, regs->csr_badvaddr); @@ -556,7 +557,7 @@ asmlinkage void noinstr do_ale(struct pt_regs *regs) die_if_kernel("Kernel ale access", regs); force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *)regs->csr_badvaddr); out: - if (regs->csr_prmd & CSR_PRMD_PIE) + if (!pie) local_irq_disable(); #endif irqentry_exit(regs, state); @@ -588,12 +589,13 @@ static void bug_handler(struct pt_regs *regs) asmlinkage void noinstr do_bce(struct pt_regs *regs) { bool user = user_mode(regs); + bool pie = regs_irqs_disabled(regs); unsigned long era = exception_era(regs); u64 badv = 0, lower = 0, upper = ULONG_MAX; union loongarch_instruction insn; irqentry_state_t state = irqentry_enter(regs);
- if (regs->csr_prmd & CSR_PRMD_PIE) + if (!pie) local_irq_enable();
current->thread.trap_nr = read_csr_excode(); @@ -659,7 +661,7 @@ asmlinkage void noinstr do_bce(struct pt_regs *regs) force_sig_bnderr((void __user *)badv, (void __user *)lower, (void __user *)upper);
out: - if (regs->csr_prmd & CSR_PRMD_PIE) + if (!pie) local_irq_disable();
irqentry_exit(regs, state); @@ -677,11 +679,12 @@ asmlinkage void noinstr do_bce(struct pt_regs *regs) asmlinkage void noinstr do_bp(struct pt_regs *regs) { bool user = user_mode(regs); + bool pie = regs_irqs_disabled(regs); unsigned int opcode, bcode; unsigned long era = exception_era(regs); irqentry_state_t state = irqentry_enter(regs);
- if (regs->csr_prmd & CSR_PRMD_PIE) + if (!pie) local_irq_enable();
if (__get_inst(&opcode, (u32 *)era, user)) @@ -747,7 +750,7 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs) }
out: - if (regs->csr_prmd & CSR_PRMD_PIE) + if (!pie) local_irq_disable();
irqentry_exit(regs, state); @@ -982,6 +985,7 @@ static void init_restore_lbt(void)
asmlinkage void noinstr do_lbt(struct pt_regs *regs) { + bool pie = regs_irqs_disabled(regs); irqentry_state_t state = irqentry_enter(regs);
/* @@ -991,7 +995,7 @@ asmlinkage void noinstr do_lbt(struct pt_regs *regs) * (including the user using 'MOVGR2GCSR' to turn on TM, which * will not trigger the BTE), we need to check PRMD first. */ - if (regs->csr_prmd & CSR_PRMD_PIE) + if (!pie) local_irq_enable();
if (!cpu_has_lbt) { @@ -1005,7 +1009,7 @@ asmlinkage void noinstr do_lbt(struct pt_regs *regs) preempt_enable();
out: - if (regs->csr_prmd & CSR_PRMD_PIE) + if (!pie) local_irq_disable();
irqentry_exit(regs, state);