From f503b5ae53cb557ac351a668fcac1baab1cef0db Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Thu, 20 May 2010 21:04:25 -0500 Subject: x86,kgdb: Add low level debug hook The only way the debugger can handle a trap in inside rcu_lock, notify_die, or atomic_notifier_call_chain without a triple fault is to have a low level "first opportunity handler" in the int3 exception handler. Generally this will be something the vast majority of folks will not need, but for those who need it, it is added as a kernel .config option called KGDB_LOW_LEVEL_TRAP. CC: Ingo Molnar CC: Thomas Gleixner CC: H. Peter Anvin CC: x86@kernel.org Signed-off-by: Jason Wessel --- arch/x86/kernel/traps.c | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'arch/x86/kernel/traps.c') diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 02cfb9b8f5b..7eaad4c5110 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include #include @@ -451,6 +452,11 @@ void restart_nmi(void) /* May run on IST stack. */ dotraplinkage void __kprobes do_int3(struct pt_regs *regs, long error_code) { +#ifdef CONFIG_KGDB_LOW_LEVEL_TRAP + if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP) + == NOTIFY_STOP) + return; +#endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */ #ifdef CONFIG_KPROBES if (notify_die(DIE_INT3, "int3", regs, error_code, 3, SIGTRAP) == NOTIFY_STOP) -- cgit v1.2.3-70-g09d2 From 29c843912a0baa7fa63033fe28e1ca7e796686a5 Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Thu, 20 May 2010 21:04:29 -0500 Subject: x86, kgdb: early trap init for early debug Allow the x86 arch to have early exception processing for the purpose of debugging via the kgdb. Signed-off-by: Jan Kiszka Signed-off-by: Jason Wessel --- arch/x86/include/asm/processor.h | 2 ++ arch/x86/kernel/setup.c | 1 + arch/x86/kernel/traps.c | 14 ++++++++++---- 3 files changed, 13 insertions(+), 4 deletions(-) (limited to 'arch/x86/kernel/traps.c') diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 5a51379dcbe..7e5c6a60b8e 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -789,6 +789,8 @@ static inline void wbinvd_halt(void) extern void enable_sep_cpu(void); extern int sysenter_setup(void); +extern void early_trap_init(void); + /* Defined in head.S */ extern struct desc_ptr early_gdt_descr; diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index c4851eff57b..e8029896309 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -725,6 +725,7 @@ void __init setup_arch(char **cmdline_p) /* VMI may relocate the fixmap; do this before touching ioremap area */ vmi_init(); + early_trap_init(); early_cpu_init(); early_ioremap_init(); diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 7eaad4c5110..142d70c74b0 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -808,6 +808,16 @@ dotraplinkage void do_iret_error(struct pt_regs *regs, long error_code) } #endif +/* Set of traps needed for early debugging. */ +void __init early_trap_init(void) +{ + set_intr_gate_ist(1, &debug, DEBUG_STACK); + /* int3 can be called from all */ + set_system_intr_gate_ist(3, &int3, DEBUG_STACK); + set_intr_gate(14, &page_fault); + load_idt(&idt_descr); +} + void __init trap_init(void) { int i; @@ -821,10 +831,7 @@ void __init trap_init(void) #endif set_intr_gate(0, ÷_error); - set_intr_gate_ist(1, &debug, DEBUG_STACK); set_intr_gate_ist(2, &nmi, NMI_STACK); - /* int3 can be called from all */ - set_system_intr_gate_ist(3, &int3, DEBUG_STACK); /* int4 can be called from all */ set_system_intr_gate(4, &overflow); set_intr_gate(5, &bounds); @@ -840,7 +847,6 @@ void __init trap_init(void) set_intr_gate(11, &segment_not_present); set_intr_gate_ist(12, &stack_segment, STACKFAULT_STACK); set_intr_gate(13, &general_protection); - set_intr_gate(14, &page_fault); set_intr_gate(15, &spurious_interrupt_bug); set_intr_gate(16, &coprocessor_error); set_intr_gate(17, &alignment_check); -- cgit v1.2.3-70-g09d2