x86/traps: Enable DEBUG_STACK after cpu_init() for TRAP_DB/BP (b4d83270) · Commits · 戴 / test

Before this patch early_trap_init() installs DEBUG_STACK for X86_TRAP_BP and X86_TRAP_DB. However, DEBUG_STACK doesn't work correctly until cpu_init() <-- trap_init(). This patch passes 0 to set_intr_gate_ist() and set_system_intr_gate_ist() instead of DEBUG_STACK to let it use same stack as kernel, and installs DEBUG_STACK for them in trap_init(). As core runs at ring 0 between early_trap_init() and trap_init(), there is no chance to get a bad stack before trap_init(). As NMI is also enabled in trap_init(), we don't need to care about is_debug_stack() and related things used in arch/x86/kernel/nmi.c. Signed-off-by:

Wang Nan <wangnan0@huawei.com> Reviewed-by:

Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Acked-by:

Steven Rostedt <rostedt@goodmis.org> Cc: <dave.hansen@linux.intel.com> Cc: <lizefan@huawei.com> Cc: <luto@amacapital.net> Cc: <oleg@redhat.com> Link: http://lkml.kernel.org/r/1424929779-13174-1-git-send-email-wangnan0@huawei.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/traps.c

+19 −2

Original line number	Diff line number	Diff line
		@@ -925,9 +925,17 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code)
		/* Set of traps needed for early debugging. */
		void __init early_trap_init(void)
		{
		set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
		/*
		* Don't set ist to DEBUG_STACK as it doesn't work until TSS is
		* ready in cpu_init() <-- trap_init(). Before trap_init(), CPU
		* runs at ring 0 so it is impossible to hit an invalid stack.
		* Using the original stack works well enough at this early
		* stage. DEBUG_STACK will be equipped after cpu_init() in
		* trap_init().
		*/
		set_intr_gate_ist(X86_TRAP_DB, &debug, 0);
		/* int3 can be called from all */
		set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);
		set_system_intr_gate_ist(X86_TRAP_BP, &int3, 0);
		#ifdef CONFIG_X86_32
		set_intr_gate(X86_TRAP_PF, page_fault);
		#endif
		@@ -1005,6 +1013,15 @@ void __init trap_init(void)
		*/
		cpu_init();

		/*
		* X86_TRAP_DB and X86_TRAP_BP have been set
		* in early_trap_init(). However, DEBUG_STACK works only after
		* cpu_init() loads TSS. See comments in early_trap_init().
		*/
		set_intr_gate_ist(X86_TRAP_DB, &debug, DEBUG_STACK);
		/* int3 can be called from all */
		set_system_intr_gate_ist(X86_TRAP_BP, &int3, DEBUG_STACK);

		x86_init.irqs.trap_init();

		#ifdef CONFIG_X86_64

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