diff options
Diffstat (limited to 'arch/x86/kernel/traps.c')
| -rw-r--r-- | arch/x86/kernel/traps.c | 159 |
1 files changed, 140 insertions, 19 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 0d0e922fafc1..a9ae20579895 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -60,6 +60,7 @@ #include <asm/fixmap.h> #include <asm/mach_traps.h> #include <asm/alternative.h> +#include <asm/mpx.h> #ifdef CONFIG_X86_64 #include <asm/x86_init.h> @@ -228,37 +229,44 @@ dotraplinkage void do_##name(struct pt_regs *regs, long error_code) \ DO_ERROR(X86_TRAP_DE, SIGFPE, "divide error", divide_error) DO_ERROR(X86_TRAP_OF, SIGSEGV, "overflow", overflow) -DO_ERROR(X86_TRAP_BR, SIGSEGV, "bounds", bounds) DO_ERROR(X86_TRAP_UD, SIGILL, "invalid opcode", invalid_op) DO_ERROR(X86_TRAP_OLD_MF, SIGFPE, "coprocessor segment overrun",coprocessor_segment_overrun) DO_ERROR(X86_TRAP_TS, SIGSEGV, "invalid TSS", invalid_TSS) DO_ERROR(X86_TRAP_NP, SIGBUS, "segment not present", segment_not_present) -#ifdef CONFIG_X86_32 DO_ERROR(X86_TRAP_SS, SIGBUS, "stack segment", stack_segment) -#endif DO_ERROR(X86_TRAP_AC, SIGBUS, "alignment check", alignment_check) #ifdef CONFIG_X86_64 /* Runs on IST stack */ -dotraplinkage void do_stack_segment(struct pt_regs *regs, long error_code) -{ - enum ctx_state prev_state; - - prev_state = exception_enter(); - if (notify_die(DIE_TRAP, "stack segment", regs, error_code, - X86_TRAP_SS, SIGBUS) != NOTIFY_STOP) { - preempt_conditional_sti(regs); - do_trap(X86_TRAP_SS, SIGBUS, "stack segment", regs, error_code, NULL); - preempt_conditional_cli(regs); - } - exception_exit(prev_state); -} - dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) { static const char str[] = "double fault"; struct task_struct *tsk = current; +#ifdef CONFIG_X86_ESPFIX64 + extern unsigned char native_irq_return_iret[]; + + /* + * If IRET takes a non-IST fault on the espfix64 stack, then we + * end up promoting it to a doublefault. In that case, modify + * the stack to make it look like we just entered the #GP + * handler from user space, similar to bad_iret. + */ + if (((long)regs->sp >> PGDIR_SHIFT) == ESPFIX_PGD_ENTRY && + regs->cs == __KERNEL_CS && + regs->ip == (unsigned long)native_irq_return_iret) + { + struct pt_regs *normal_regs = task_pt_regs(current); + + /* Fake a #GP(0) from userspace. */ + memmove(&normal_regs->ip, (void *)regs->sp, 5*8); + normal_regs->orig_ax = 0; /* Missing (lost) #GP error code */ + regs->ip = (unsigned long)general_protection; + regs->sp = (unsigned long)&normal_regs->orig_ax; + return; + } +#endif + exception_enter(); /* Return not checked because double check cannot be ignored */ notify_die(DIE_TRAP, str, regs, error_code, X86_TRAP_DF, SIGSEGV); @@ -278,6 +286,89 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) } #endif +dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) +{ + struct task_struct *tsk = current; + struct xsave_struct *xsave_buf; + enum ctx_state prev_state; + struct bndcsr *bndcsr; + siginfo_t *info; + + prev_state = exception_enter(); + if (notify_die(DIE_TRAP, "bounds", regs, error_code, + X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP) + goto exit; + conditional_sti(regs); + + if (!user_mode(regs)) + die("bounds", regs, error_code); + + if (!cpu_feature_enabled(X86_FEATURE_MPX)) { + /* The exception is not from Intel MPX */ + goto exit_trap; + } + + /* + * We need to look at BNDSTATUS to resolve this exception. + * It is not directly accessible, though, so we need to + * do an xsave and then pull it out of the xsave buffer. + */ + fpu_save_init(&tsk->thread.fpu); + xsave_buf = &(tsk->thread.fpu.state->xsave); + bndcsr = get_xsave_addr(xsave_buf, XSTATE_BNDCSR); + if (!bndcsr) + goto exit_trap; + + /* + * The error code field of the BNDSTATUS register communicates status + * information of a bound range exception #BR or operation involving + * bound directory. + */ + switch (bndcsr->bndstatus & MPX_BNDSTA_ERROR_CODE) { + case 2: /* Bound directory has invalid entry. */ + if (mpx_handle_bd_fault(xsave_buf)) + goto exit_trap; + break; /* Success, it was handled */ + case 1: /* Bound violation. */ + info = mpx_generate_siginfo(regs, xsave_buf); + if (PTR_ERR(info)) { + /* + * We failed to decode the MPX instruction. Act as if + * the exception was not caused by MPX. + */ + goto exit_trap; + } + /* + * Success, we decoded the instruction and retrieved + * an 'info' containing the address being accessed + * which caused the exception. This information + * allows and application to possibly handle the + * #BR exception itself. + */ + do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, info); + kfree(info); + break; + case 0: /* No exception caused by Intel MPX operations. */ + goto exit_trap; + default: + die("bounds", regs, error_code); + } + +exit: + exception_exit(prev_state); + return; +exit_trap: + /* + * This path out is for all the cases where we could not + * handle the exception in some way (like allocating a + * table or telling userspace about it. We will also end + * up here if the kernel has MPX turned off at compile + * time.. + */ + do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, NULL); + exception_exit(prev_state); +} + dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) { @@ -379,7 +470,7 @@ NOKPROBE_SYMBOL(do_int3); * for scheduling or signal handling. The actual stack switch is done in * entry.S */ -asmlinkage __visible struct pt_regs *sync_regs(struct pt_regs *eregs) +asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs) { struct pt_regs *regs = eregs; /* Did already sync */ @@ -399,6 +490,36 @@ asmlinkage __visible struct pt_regs *sync_regs(struct pt_regs *eregs) return regs; } NOKPROBE_SYMBOL(sync_regs); + +struct bad_iret_stack { + void *error_entry_ret; + struct pt_regs regs; +}; + +asmlinkage __visible notrace +struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s) +{ + /* + * This is called from entry_64.S early in handling a fault + * caused by a bad iret to user mode. To handle the fault + * correctly, we want move our stack frame to task_pt_regs + * and we want to pretend that the exception came from the + * iret target. + */ + struct bad_iret_stack *new_stack = + container_of(task_pt_regs(current), + struct bad_iret_stack, regs); + + /* Copy the IRET target to the new stack. */ + memmove(&new_stack->regs.ip, (void *)s->regs.sp, 5*8); + + /* Copy the remainder of the stack from the current stack. */ + memmove(new_stack, s, offsetof(struct bad_iret_stack, regs.ip)); + + BUG_ON(!user_mode_vm(&new_stack->regs)); + return new_stack; +} +NOKPROBE_SYMBOL(fixup_bad_iret); #endif /* @@ -778,7 +899,7 @@ void __init trap_init(void) set_intr_gate(X86_TRAP_OLD_MF, coprocessor_segment_overrun); set_intr_gate(X86_TRAP_TS, invalid_TSS); set_intr_gate(X86_TRAP_NP, segment_not_present); - set_intr_gate_ist(X86_TRAP_SS, &stack_segment, STACKFAULT_STACK); + set_intr_gate(X86_TRAP_SS, stack_segment); set_intr_gate(X86_TRAP_GP, general_protection); set_intr_gate(X86_TRAP_SPURIOUS, spurious_interrupt_bug); set_intr_gate(X86_TRAP_MF, coprocessor_error); |