diff options
Diffstat (limited to 'arch/x86/kernel/traps.c')
| -rw-r--r-- | arch/x86/kernel/traps.c | 35 |
1 files changed, 20 insertions, 15 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 679302c312f8..6223929fc621 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -61,6 +61,7 @@ #include <asm/alternative.h> #include <asm/fpu/xstate.h> #include <asm/trace/mpx.h> +#include <asm/nospec-branch.h> #include <asm/mpx.h> #include <asm/vm86.h> @@ -166,7 +167,7 @@ void ist_begin_non_atomic(struct pt_regs *regs) * from double_fault. */ BUG_ON((unsigned long)(current_top_of_stack() - - current_stack_pointer()) >= THREAD_SIZE); + current_stack_pointer) >= THREAD_SIZE); preempt_enable_no_resched(); } @@ -337,6 +338,13 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) regs->ip = (unsigned long)general_protection; regs->sp = (unsigned long)&normal_regs->orig_ax; + /* + * This situation can be triggered by userspace via + * modify_ldt(2) and the return does not take the regular + * user space exit, so a CPU buffer clear is required when + * MDS mitigation is enabled. + */ + mds_user_clear_cpu_buffers(); return; } #endif @@ -480,7 +488,6 @@ do_general_protection(struct pt_regs *regs, long error_code) } NOKPROBE_SYMBOL(do_general_protection); -/* May run on IST stack. */ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code) { #ifdef CONFIG_DYNAMIC_FTRACE @@ -495,7 +502,15 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code) if (poke_int3_handler(regs)) return; + /* + * Use ist_enter despite the fact that we don't use an IST stack. + * We can be called from a kprobe in non-CONTEXT_KERNEL kernel + * mode or even during context tracking state changes. + * + * This means that we can't schedule. That's okay. + */ ist_enter(regs); + RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP if (kgdb_ll_trap(DIE_INT3, "int3", regs, error_code, X86_TRAP_BP, @@ -512,15 +527,9 @@ dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code) SIGTRAP) == NOTIFY_STOP) goto exit; - /* - * Let others (NMI) know that the debug stack is in use - * as we may switch to the interrupt stack. - */ - debug_stack_usage_inc(); preempt_conditional_sti(regs); do_trap(X86_TRAP_BP, SIGTRAP, "int3", regs, error_code, NULL); preempt_conditional_cli(regs); - debug_stack_usage_dec(); exit: ist_exit(regs); } @@ -750,7 +759,6 @@ dotraplinkage void do_device_not_available(struct pt_regs *regs, long error_code) { RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); - BUG_ON(use_eager_fpu()); #ifdef CONFIG_MATH_EMULATION if (read_cr0() & X86_CR0_EM) { @@ -886,19 +894,16 @@ void __init trap_init(void) cpu_init(); /* - * X86_TRAP_DB and X86_TRAP_BP have been set - * in early_trap_init(). However, ITS works only after - * cpu_init() loads TSS. See comments in early_trap_init(). + * X86_TRAP_DB was installed in early_trap_init(). However, + * IST 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 memcpy(&debug_idt_table, &idt_table, IDT_ENTRIES * 16); set_nmi_gate(X86_TRAP_DB, &debug); - set_nmi_gate(X86_TRAP_BP, &int3); #endif } |