x86/entry: Fix #UD vs WARN more (145a773a) · Commits · 戴 / test

arch/x86/kernel/traps.c

+38 −34

Original line number	Diff line number	Diff line
		@@ -84,17 +84,16 @@ static inline void cond_local_irq_disable(struct pt_regs *regs)
		local_irq_disable();
		}

		int is_valid_bugaddr(unsigned long addr)
		__always_inline int is_valid_bugaddr(unsigned long addr)
		{
		unsigned short ud;

		if (addr < TASK_SIZE_MAX)
		return 0;

		if (probe_kernel_address((unsigned short *)addr, ud))
		return 0;

		return ud == INSN_UD0 \|\| ud == INSN_UD2;
		/*
		* We got #UD, if the text isn't readable we'd have gotten
		* a different exception.
		*/
		return (unsigned short )addr == INSN_UD2;
		}

		static nokprobe_inline int
		@@ -216,40 +215,45 @@ static inline void handle_invalid_op(struct pt_regs *regs)
		ILL_ILLOPN, error_get_trap_addr(regs));
		}

		DEFINE_IDTENTRY_RAW(exc_invalid_op)
		static noinstr bool handle_bug(struct pt_regs *regs)
		{
		bool rcu_exit;
		bool handled = false;

		if (!is_valid_bugaddr(regs->ip))
		return handled;

		/*
		* Handle BUG/WARN like NMIs instead of like normal idtentries:
		* if we bugged/warned in a bad RCU context, for example, the last
		* thing we want is to BUG/WARN again in the idtentry code, ad
		* infinitum.
		* All lies, just get the WARN/BUG out.
		*/
		if (!user_mode(regs) && is_valid_bugaddr(regs->ip)) {
		enum bug_trap_type type;

		nmi_enter();
		instrumentation_begin();
		trace_hardirqs_off_finish();
		type = report_bug(regs->ip, regs);
		/*
		* Since we're emulating a CALL with exceptions, restore the interrupt
		* state to what it was at the exception site.
		*/
		if (regs->flags & X86_EFLAGS_IF)
		trace_hardirqs_on_prepare();
		raw_local_irq_enable();
		if (report_bug(regs->ip, regs) == BUG_TRAP_TYPE_WARN) {
		regs->ip += LEN_UD2;
		handled = true;
		}
		if (regs->flags & X86_EFLAGS_IF)
		raw_local_irq_disable();
		instrumentation_end();
		nmi_exit();

		if (type == BUG_TRAP_TYPE_WARN) {
		/* Skip the ud2. */
		regs->ip += LEN_UD2;
		return;
		return handled;
		}

		DEFINE_IDTENTRY_RAW(exc_invalid_op)
		{
		bool rcu_exit;

		/*
		* Else, if this was a BUG and report_bug returns or if this
		* was just a normal #UD, we want to continue onward and
		* crash.
		* We use UD2 as a short encoding for 'CALL __WARN', as such
		* handle it before exception entry to avoid recursive WARN
		* in case exception entry is the one triggering WARNs.
		*/
		}
		if (!user_mode(regs) && handle_bug(regs))
		return;

		rcu_exit = idtentry_enter_cond_rcu(regs);
		instrumentation_begin();

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