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x86/entry: Fix #UD vs WARN more
vmlinux.o: warning: objtool: exc_invalid_op()+0x47: call to probe_kernel_read() leaves .noinstr.text section
Since we use UD2 as a short-cut for 'CALL __WARN', treat it as such.
Have the bare exception handler do the report_bug() thing.
Fixes: 15a416e8aa
("x86/entry: Treat BUG/WARN as NMI-like entries")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Andy Lutomirski <luto@kernel.org>
Link: https://lkml.kernel.org/r/20200622114713.GE577403@hirez.programming.kicks-ass.net
This commit is contained in:
parent
c7aadc0932
commit
145a773aef
1 changed files with 39 additions and 35 deletions
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@ -84,17 +84,16 @@ static inline void cond_local_irq_disable(struct pt_regs *regs)
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local_irq_disable();
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}
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int is_valid_bugaddr(unsigned long addr)
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__always_inline int is_valid_bugaddr(unsigned long addr)
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{
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unsigned short ud;
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if (addr < TASK_SIZE_MAX)
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return 0;
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if (probe_kernel_address((unsigned short *)addr, ud))
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return 0;
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return ud == INSN_UD0 || ud == INSN_UD2;
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/*
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* We got #UD, if the text isn't readable we'd have gotten
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* a different exception.
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*/
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return *(unsigned short *)addr == INSN_UD2;
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}
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static nokprobe_inline int
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@ -216,40 +215,45 @@ static inline void handle_invalid_op(struct pt_regs *regs)
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ILL_ILLOPN, error_get_trap_addr(regs));
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}
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static noinstr bool handle_bug(struct pt_regs *regs)
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{
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bool handled = false;
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if (!is_valid_bugaddr(regs->ip))
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return handled;
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/*
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* All lies, just get the WARN/BUG out.
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*/
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instrumentation_begin();
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/*
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* Since we're emulating a CALL with exceptions, restore the interrupt
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* state to what it was at the exception site.
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*/
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if (regs->flags & X86_EFLAGS_IF)
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raw_local_irq_enable();
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if (report_bug(regs->ip, regs) == BUG_TRAP_TYPE_WARN) {
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regs->ip += LEN_UD2;
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handled = true;
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}
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if (regs->flags & X86_EFLAGS_IF)
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raw_local_irq_disable();
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instrumentation_end();
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return handled;
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}
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DEFINE_IDTENTRY_RAW(exc_invalid_op)
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{
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bool rcu_exit;
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/*
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* Handle BUG/WARN like NMIs instead of like normal idtentries:
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* if we bugged/warned in a bad RCU context, for example, the last
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* thing we want is to BUG/WARN again in the idtentry code, ad
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* infinitum.
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* We use UD2 as a short encoding for 'CALL __WARN', as such
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* handle it before exception entry to avoid recursive WARN
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* in case exception entry is the one triggering WARNs.
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*/
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if (!user_mode(regs) && is_valid_bugaddr(regs->ip)) {
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enum bug_trap_type type;
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nmi_enter();
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instrumentation_begin();
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trace_hardirqs_off_finish();
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type = report_bug(regs->ip, regs);
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if (regs->flags & X86_EFLAGS_IF)
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trace_hardirqs_on_prepare();
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instrumentation_end();
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nmi_exit();
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if (type == BUG_TRAP_TYPE_WARN) {
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/* Skip the ud2. */
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regs->ip += LEN_UD2;
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return;
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}
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/*
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* Else, if this was a BUG and report_bug returns or if this
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* was just a normal #UD, we want to continue onward and
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* crash.
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*/
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}
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if (!user_mode(regs) && handle_bug(regs))
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return;
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rcu_exit = idtentry_enter_cond_rcu(regs);
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instrumentation_begin();
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