diff options
Diffstat (limited to 'arch/x86/kernel/traps.c')
-rw-r--r-- | arch/x86/kernel/traps.c | 177 |
1 files changed, 82 insertions, 95 deletions
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 05da6b5b167b..6ef00eb6fbb9 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -52,10 +52,10 @@ #include <asm/mach_traps.h> #include <asm/alternative.h> #include <asm/fpu/xstate.h> -#include <asm/trace/mpx.h> -#include <asm/mpx.h> #include <asm/vm86.h> #include <asm/umip.h> +#include <asm/insn.h> +#include <asm/insn-eval.h> #ifdef CONFIG_X86_64 #include <asm/x86_init.h> @@ -434,8 +434,6 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code, unsign dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) { - const struct mpx_bndcsr *bndcsr; - RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); if (notify_die(DIE_TRAP, "bounds", regs, error_code, X86_TRAP_BR, SIGSEGV) == NOTIFY_STOP) @@ -445,84 +443,60 @@ dotraplinkage void do_bounds(struct pt_regs *regs, long error_code) 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; - } + do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, 0, NULL); +} - /* - * We need to look at BNDSTATUS to resolve this exception. - * A NULL here might mean that it is in its 'init state', - * which is all zeros which indicates MPX was not - * responsible for the exception. - */ - bndcsr = get_xsave_field_ptr(XFEATURE_BNDCSR); - if (!bndcsr) - goto exit_trap; +enum kernel_gp_hint { + GP_NO_HINT, + GP_NON_CANONICAL, + GP_CANONICAL +}; - trace_bounds_exception_mpx(bndcsr); - /* - * 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()) - goto exit_trap; - break; /* Success, it was handled */ - case 1: /* Bound violation. */ - { - struct task_struct *tsk = current; - struct mpx_fault_info mpx; - - if (mpx_fault_info(&mpx, regs)) { - /* - * 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 'mpx' containing the address being accessed - * which caused the exception. This information - * allows and application to possibly handle the - * #BR exception itself. - */ - if (!do_trap_no_signal(tsk, X86_TRAP_BR, "bounds", regs, - error_code)) - break; +/* + * When an uncaught #GP occurs, try to determine the memory address accessed by + * the instruction and return that address to the caller. Also, try to figure + * out whether any part of the access to that address was non-canonical. + */ +static enum kernel_gp_hint get_kernel_gp_address(struct pt_regs *regs, + unsigned long *addr) +{ + u8 insn_buf[MAX_INSN_SIZE]; + struct insn insn; - show_signal(tsk, SIGSEGV, "trap ", "bounds", regs, error_code); + if (probe_kernel_read(insn_buf, (void *)regs->ip, MAX_INSN_SIZE)) + return GP_NO_HINT; - force_sig_bnderr(mpx.addr, mpx.lower, mpx.upper); - break; - } - case 0: /* No exception caused by Intel MPX operations. */ - goto exit_trap; - default: - die("bounds", regs, error_code); - } + kernel_insn_init(&insn, insn_buf, MAX_INSN_SIZE); + insn_get_modrm(&insn); + insn_get_sib(&insn); - return; + *addr = (unsigned long)insn_get_addr_ref(&insn, regs); + if (*addr == -1UL) + return GP_NO_HINT; -exit_trap: +#ifdef CONFIG_X86_64 /* - * 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.. + * Check that: + * - the operand is not in the kernel half + * - the last byte of the operand is not in the user canonical half */ - do_trap(X86_TRAP_BR, SIGSEGV, "bounds", regs, error_code, 0, NULL); + if (*addr < ~__VIRTUAL_MASK && + *addr + insn.opnd_bytes - 1 > __VIRTUAL_MASK) + return GP_NON_CANONICAL; +#endif + + return GP_CANONICAL; } -dotraplinkage void -do_general_protection(struct pt_regs *regs, long error_code) +#define GPFSTR "general protection fault" + +dotraplinkage void do_general_protection(struct pt_regs *regs, long error_code) { - const char *desc = "general protection fault"; + char desc[sizeof(GPFSTR) + 50 + 2*sizeof(unsigned long) + 1] = GPFSTR; + enum kernel_gp_hint hint = GP_NO_HINT; struct task_struct *tsk; + unsigned long gp_addr; + int ret; RCU_LOCKDEP_WARN(!rcu_is_watching(), "entry code didn't wake RCU"); cond_local_irq_enable(regs); @@ -539,48 +513,61 @@ do_general_protection(struct pt_regs *regs, long error_code) } tsk = current; - if (!user_mode(regs)) { - if (fixup_exception(regs, X86_TRAP_GP, error_code, 0)) - return; + if (user_mode(regs)) { tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_GP; - /* - * To be potentially processing a kprobe fault and to - * trust the result from kprobe_running(), we have to - * be non-preemptible. - */ - if (!preemptible() && kprobe_running() && - kprobe_fault_handler(regs, X86_TRAP_GP)) - return; + show_signal(tsk, SIGSEGV, "", desc, regs, error_code); + force_sig(SIGSEGV); - if (notify_die(DIE_GPF, desc, regs, error_code, - X86_TRAP_GP, SIGSEGV) != NOTIFY_STOP) - die(desc, regs, error_code); return; } + if (fixup_exception(regs, X86_TRAP_GP, error_code, 0)) + return; + tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_GP; - show_signal(tsk, SIGSEGV, "", desc, regs, error_code); + /* + * To be potentially processing a kprobe fault and to trust the result + * from kprobe_running(), we have to be non-preemptible. + */ + if (!preemptible() && + kprobe_running() && + kprobe_fault_handler(regs, X86_TRAP_GP)) + return; + + ret = notify_die(DIE_GPF, desc, regs, error_code, X86_TRAP_GP, SIGSEGV); + if (ret == NOTIFY_STOP) + return; + + if (error_code) + snprintf(desc, sizeof(desc), "segment-related " GPFSTR); + else + hint = get_kernel_gp_address(regs, &gp_addr); + + if (hint != GP_NO_HINT) + snprintf(desc, sizeof(desc), GPFSTR ", %s 0x%lx", + (hint == GP_NON_CANONICAL) ? "probably for non-canonical address" + : "maybe for address", + gp_addr); + + /* + * KASAN is interested only in the non-canonical case, clear it + * otherwise. + */ + if (hint != GP_NON_CANONICAL) + gp_addr = 0; + + die_addr(desc, regs, error_code, gp_addr); - force_sig(SIGSEGV); } NOKPROBE_SYMBOL(do_general_protection); dotraplinkage void notrace do_int3(struct pt_regs *regs, long error_code) { -#ifdef CONFIG_DYNAMIC_FTRACE - /* - * ftrace must be first, everything else may cause a recursive crash. - * See note by declaration of modifying_ftrace_code in ftrace.c - */ - if (unlikely(atomic_read(&modifying_ftrace_code)) && - ftrace_int3_handler(regs)) - return; -#endif if (poke_int3_handler(regs)) return; |