From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753057AbdLDRHn (ORCPT ); Mon, 4 Dec 2017 12:07:43 -0500 Received: from Galois.linutronix.de ([146.0.238.70]:59754 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752234AbdLDQux (ORCPT ); Mon, 4 Dec 2017 11:50:53 -0500 Message-Id: <20171204150605.392711508@linutronix.de> User-Agent: quilt/0.63-1 Date: Mon, 04 Dec 2017 15:07:13 +0100 From: Thomas Gleixner To: LKML Cc: x86@kernel.org, Linus Torvalds , Andy Lutomirsky , Peter Zijlstra , Dave Hansen , Borislav Petkov , Greg KH , keescook@google.com, hughd@google.com, Brian Gerst , Josh Poimboeuf , Denys Vlasenko , Rik van Riel , Boris Ostrovsky , Juergen Gross , David Laight , Eduardo Valentin , aliguori@amazon.com, Will Deacon , daniel.gruss@iaik.tugraz.at, Ingo Molnar , Borislav Petkov , Dave Hansen Subject: [patch 07/60] x86/dumpstack: Add get_stack_info() support for the SYSENTER stack References: <20171204140706.296109558@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Disposition: inline; filename=x86-dumpstack--Add_get_stack_info__support_for_the_SYSENTER_stack.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Andy Lutomirski get_stack_info() doesn't currently know about the SYSENTER stack, so unwinding will fail if we entered the kernel on the SYSENTER stack and haven't fully switched off. Teach get_stack_info() about the SYSENTER stack. With future patches applied that run part of the entry code on the SYSENTER stack and introduce an intentional BUG(), I would get: PANIC: double fault, error_code: 0x0 ... RIP: 0010:do_error_trap+0x33/0x1c0 ... Call Trace: Code: ... With this patch, I get: PANIC: double fault, error_code: 0x0 ... Call Trace: ? async_page_fault+0x36/0x60 ? invalid_op+0x22/0x40 ? async_page_fault+0x36/0x60 ? sync_regs+0x3c/0x40 ? sync_regs+0x2e/0x40 ? error_entry+0x6c/0xd0 ? async_page_fault+0x36/0x60 Code: ... which is a lot more informative. Signed-off-by: Andy Lutomirski Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner Reviewed-by: Borislav Petkov Cc: Rik van Riel Cc: Denys Vlasenko Cc: Peter Zijlstra Cc: Brian Gerst Cc: Dave Hansen Cc: Josh Poimboeuf Cc: Linus Torvalds Link: https://lkml.kernel.org/r/c32ce8b363e27fa9b4a4773297d5b4b0f4b39e94.1511497875.git.luto@kernel.org --- arch/x86/include/asm/stacktrace.h | 3 +++ arch/x86/kernel/dumpstack.c | 19 +++++++++++++++++++ arch/x86/kernel/dumpstack_32.c | 6 ++++++ arch/x86/kernel/dumpstack_64.c | 6 ++++++ 4 files changed, 34 insertions(+) --- a/arch/x86/include/asm/stacktrace.h +++ b/arch/x86/include/asm/stacktrace.h @@ -16,6 +16,7 @@ enum stack_type { STACK_TYPE_TASK, STACK_TYPE_IRQ, STACK_TYPE_SOFTIRQ, + STACK_TYPE_SYSENTER, STACK_TYPE_EXCEPTION, STACK_TYPE_EXCEPTION_LAST = STACK_TYPE_EXCEPTION + N_EXCEPTION_STACKS-1, }; @@ -28,6 +29,8 @@ struct stack_info { bool in_task_stack(unsigned long *stack, struct task_struct *task, struct stack_info *info); +bool in_sysenter_stack(unsigned long *stack, struct stack_info *info); + int get_stack_info(unsigned long *stack, struct task_struct *task, struct stack_info *info, unsigned long *visit_mask); --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -43,6 +43,25 @@ bool in_task_stack(unsigned long *stack, return true; } +bool in_sysenter_stack(unsigned long *stack, struct stack_info *info) +{ + struct tss_struct *tss = this_cpu_ptr(&cpu_tss); + + /* Treat the canary as part of the stack for unwinding purposes. */ + void *begin = &tss->SYSENTER_stack_canary; + void *end = (void *)&tss->SYSENTER_stack + sizeof(tss->SYSENTER_stack); + + if ((void *)stack < begin || (void *)stack >= end) + return false; + + info->type = STACK_TYPE_SYSENTER; + info->begin = begin; + info->end = end; + info->next_sp = NULL; + + return true; +} + static void printk_stack_address(unsigned long address, int reliable, char *log_lvl) { --- a/arch/x86/kernel/dumpstack_32.c +++ b/arch/x86/kernel/dumpstack_32.c @@ -26,6 +26,9 @@ const char *stack_type_name(enum stack_t if (type == STACK_TYPE_SOFTIRQ) return "SOFTIRQ"; + if (type == STACK_TYPE_SYSENTER) + return "SYSENTER"; + return NULL; } @@ -93,6 +96,9 @@ int get_stack_info(unsigned long *stack, if (task != current) goto unknown; + if (in_sysenter_stack(stack, info)) + goto recursion_check; + if (in_hardirq_stack(stack, info)) goto recursion_check; --- a/arch/x86/kernel/dumpstack_64.c +++ b/arch/x86/kernel/dumpstack_64.c @@ -37,6 +37,9 @@ const char *stack_type_name(enum stack_t if (type == STACK_TYPE_IRQ) return "IRQ"; + if (type == STACK_TYPE_SYSENTER) + return "SYSENTER"; + if (type >= STACK_TYPE_EXCEPTION && type <= STACK_TYPE_EXCEPTION_LAST) return exception_stack_names[type - STACK_TYPE_EXCEPTION]; @@ -115,6 +118,9 @@ int get_stack_info(unsigned long *stack, if (in_irq_stack(stack, info)) goto recursion_check; + if (in_sysenter_stack(stack, info)) + goto recursion_check; + goto unknown; recursion_check: