The following commit has been merged into the x86/entry branch of tip: Commit-ID: 8449e768dcb85b4d8db51482d8c9260bb05ccabc Gitweb: https://git.kernel.org/tip/8449e768dcb85b4d8db51482d8c9260bb05ccabc Author: Peter Zijlstra <pet...@infradead.org> AuthorDate: Fri, 29 May 2020 23:27:37 +02:00 Committer: Thomas Gleixner <t...@linutronix.de> CommitterDate: Sat, 30 May 2020 10:00:09 +02:00
x86/entry: Remove debug IDT frobbing This is all unused now. Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Link: https://lkml.kernel.org/r/20200529213321.245019...@infradead.org --- arch/x86/include/asm/debugreg.h | 19 +------------------ arch/x86/include/asm/desc.h | 34 +-------------------------------- arch/x86/kernel/cpu/common.c | 17 +---------------- arch/x86/kernel/idt.c | 30 +---------------------------- arch/x86/kernel/traps.c | 9 +-------- 5 files changed, 1 insertion(+), 108 deletions(-) diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h index 3e1c502..42fc35d 100644 --- a/arch/x86/include/asm/debugreg.h +++ b/arch/x86/include/asm/debugreg.h @@ -94,25 +94,6 @@ extern void aout_dump_debugregs(struct user *dump); extern void hw_breakpoint_restore(void); -#ifdef CONFIG_X86_64 -DECLARE_PER_CPU(int, debug_stack_usage); -static inline void debug_stack_usage_inc(void) -{ - __this_cpu_inc(debug_stack_usage); -} -static inline void debug_stack_usage_dec(void) -{ - __this_cpu_dec(debug_stack_usage); -} -void debug_stack_set_zero(void); -void debug_stack_reset(void); -#else /* !X86_64 */ -static inline void debug_stack_set_zero(void) { } -static inline void debug_stack_reset(void) { } -static inline void debug_stack_usage_inc(void) { } -static inline void debug_stack_usage_dec(void) { } -#endif /* X86_64 */ - static __always_inline unsigned long local_db_save(void) { unsigned long dr7; diff --git a/arch/x86/include/asm/desc.h b/arch/x86/include/asm/desc.h index d6c3d34..07632f3 100644 --- a/arch/x86/include/asm/desc.h +++ b/arch/x86/include/asm/desc.h @@ -42,8 +42,6 @@ static inline void fill_ldt(struct desc_struct *desc, const struct user_desc *in extern struct desc_ptr idt_descr; extern gate_desc idt_table[]; -extern const struct desc_ptr debug_idt_descr; -extern gate_desc debug_idt_table[]; struct gdt_page { struct desc_struct gdt[GDT_ENTRIES]; @@ -390,31 +388,6 @@ void alloc_intr_gate(unsigned int n, const void *addr); extern unsigned long system_vectors[]; -#ifdef CONFIG_X86_64 -DECLARE_PER_CPU(u32, debug_idt_ctr); -static __always_inline bool is_debug_idt_enabled(void) -{ - if (this_cpu_read(debug_idt_ctr)) - return true; - - return false; -} - -static __always_inline void load_debug_idt(void) -{ - load_idt((const struct desc_ptr *)&debug_idt_descr); -} -#else -static inline bool is_debug_idt_enabled(void) -{ - return false; -} - -static inline void load_debug_idt(void) -{ -} -#endif - /* * The load_current_idt() must be called with interrupts disabled * to avoid races. That way the IDT will always be set back to the expected @@ -424,10 +397,7 @@ static inline void load_debug_idt(void) */ static __always_inline void load_current_idt(void) { - if (is_debug_idt_enabled()) - load_debug_idt(); - else - load_idt((const struct desc_ptr *)&idt_descr); + load_idt((const struct desc_ptr *)&idt_descr); } extern void idt_setup_early_handler(void); @@ -438,11 +408,9 @@ extern void idt_setup_apic_and_irq_gates(void); #ifdef CONFIG_X86_64 extern void idt_setup_early_pf(void); extern void idt_setup_ist_traps(void); -extern void idt_setup_debugidt_traps(void); #else static inline void idt_setup_early_pf(void) { } static inline void idt_setup_ist_traps(void) { } -static inline void idt_setup_debugidt_traps(void) { } #endif extern void idt_invalidate(void *addr); diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 6751b81..c55be3b 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1689,23 +1689,6 @@ void syscall_init(void) X86_EFLAGS_IOPL|X86_EFLAGS_AC|X86_EFLAGS_NT); } -DEFINE_PER_CPU(int, debug_stack_usage); -DEFINE_PER_CPU(u32, debug_idt_ctr); - -noinstr void debug_stack_set_zero(void) -{ - this_cpu_inc(debug_idt_ctr); - load_current_idt(); -} - -noinstr void debug_stack_reset(void) -{ - if (WARN_ON(!this_cpu_read(debug_idt_ctr))) - return; - if (this_cpu_dec_return(debug_idt_ctr) == 0) - load_current_idt(); -} - #else /* CONFIG_X86_64 */ DEFINE_PER_CPU(struct task_struct *, current_task) = &init_task; diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c index bc9b0d1..226c992 100644 --- a/arch/x86/kernel/idt.c +++ b/arch/x86/kernel/idt.c @@ -158,14 +158,6 @@ static const __initconst struct idt_data apic_idts[] = { static const __initconst struct idt_data early_pf_idts[] = { INTG(X86_TRAP_PF, asm_exc_page_fault), }; - -/* - * Override for the debug_idt. Same as the default, but with interrupt - * stack set to DEFAULT_STACK (0). Required for NMI trap handling. - */ -static const __initconst struct idt_data dbg_idts[] = { - INTG(X86_TRAP_DB, asm_exc_debug), -}; #endif /* Must be page-aligned because the real IDT is used in a fixmap. */ @@ -177,9 +169,6 @@ struct desc_ptr idt_descr __ro_after_init = { }; #ifdef CONFIG_X86_64 -/* No need to be aligned, but done to keep all IDTs defined the same way. */ -gate_desc debug_idt_table[IDT_ENTRIES] __page_aligned_bss; - /* * The exceptions which use Interrupt stacks. They are setup after * cpu_init() when the TSS has been initialized. @@ -192,15 +181,6 @@ static const __initconst struct idt_data ist_idts[] = { ISTG(X86_TRAP_MC, asm_exc_machine_check, IST_INDEX_MCE), #endif }; - -/* - * Override for the debug_idt. Same as the default, but with interrupt - * stack set to DEFAULT_STACK (0). Required for NMI trap handling. - */ -const struct desc_ptr debug_idt_descr = { - .size = IDT_ENTRIES * 16 - 1, - .address = (unsigned long) debug_idt_table, -}; #endif static inline void idt_init_desc(gate_desc *gate, const struct idt_data *d) @@ -292,16 +272,6 @@ void __init idt_setup_ist_traps(void) { idt_setup_from_table(idt_table, ist_idts, ARRAY_SIZE(ist_idts), true); } - -/** - * idt_setup_debugidt_traps - Initialize the debug idt table with debug traps - */ -void __init idt_setup_debugidt_traps(void) -{ - memcpy(&debug_idt_table, &idt_table, IDT_ENTRIES * 16); - - idt_setup_from_table(debug_idt_table, dbg_idts, ARRAY_SIZE(dbg_idts), false); -} #endif /** diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index bcb9dd9..6f887be 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -798,12 +798,6 @@ static void noinstr handle_debug(struct pt_regs *regs, unsigned long dr6, return; } - /* - * Let others (NMI) know that the debug stack is in use - * as we may switch to the interrupt stack. - */ - debug_stack_usage_inc(); - /* It's safe to allow irq's after DR6 has been saved */ cond_local_irq_enable(regs); @@ -831,7 +825,6 @@ static void noinstr handle_debug(struct pt_regs *regs, unsigned long dr6, out: cond_local_irq_disable(regs); - debug_stack_usage_dec(); instrumentation_end(); } @@ -1077,6 +1070,4 @@ void __init trap_init(void) cpu_init(); idt_setup_ist_traps(); - - idt_setup_debugidt_traps(); }
