From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY, USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 72F90C433F5 for ; Sat, 18 Sep 2021 02:30:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5924B6124B for ; Sat, 18 Sep 2021 02:30:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236100AbhIRCcM (ORCPT ); Fri, 17 Sep 2021 22:32:12 -0400 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:60009 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231364AbhIRCcK (ORCPT ); Fri, 17 Sep 2021 22:32:10 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R211e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04357;MF=yun.wang@linux.alibaba.com;NM=1;PH=DS;RN=22;SR=0;TI=SMTPD_---0UojvAV3_1631932242; Received: from testdeMacBook-Pro.local(mailfrom:yun.wang@linux.alibaba.com fp:SMTPD_---0UojvAV3_1631932242) by smtp.aliyun-inc.com(127.0.0.1); Sat, 18 Sep 2021 10:30:43 +0800 Subject: Re: [PATCH] x86/dumpstack/64: Add guard pages to stack_info To: Peter Zijlstra Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , "open list:PERFORMANCE EVENTS SUBSYSTEM" , "open list:PERFORMANCE EVENTS SUBSYSTEM" , "open list:BPF (Safe dynamic programs and tools)" , "open list:BPF (Safe dynamic programs and tools)" , jroedel@suse.de, x86@kernel.org, Josh Poimboeuf References: <3fb7c51f-696b-da70-1965-1dda9910cb14@linux.alibaba.com> <3f26f7a2-0a09-056a-3a7a-4795b6723b60@linux.alibaba.com> <76de02b7-4d87-4a3a-e4d4-048829749887@linux.alibaba.com> From: =?UTF-8?B?546L6LSH?= Message-ID: <89f8281f-b778-5bf5-13e0-2bda613d963c@linux.alibaba.com> Date: Sat, 18 Sep 2021 10:30:42 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/9/18 上午12:40, Peter Zijlstra wrote: > On Fri, Sep 17, 2021 at 12:21:24PM +0200, Peter Zijlstra wrote: >> On Fri, Sep 17, 2021 at 11:02:07AM +0800, 王贇 wrote: >>> >>> >>> On 2021/9/16 下午6:02, Peter Zijlstra wrote: >>> [snip] >>>> >>>> +static __always_inline bool in_stack_guard(void *addr, void *begin, void *end) >>>> +{ >>>> +#ifdef CONFIG_VMAP_STACK >>>> + if (addr > (begin - PAGE_SIZE)) >>>> + return true; >>> >>> After fix this logical as: >>> >>> addr >= (begin - PAGE_SIZE) && addr < begin >>> >>> it's working. >> >> Shees, I seem to have a knack for getting it wrong, don't I. Thanks! >> >> Anyway, I'll ammend the commit locally, but I'd really like some >> feedback from Andy, who wrote all that VIRT_STACK stuff in the first >> place. > > Andy suggested something like this. Now it seem like working well :-) [ 193.100475][ C0] BUG: NMI stack guard page was hit at 0000000085fd977b (stack is 000000003a55b09e..00000000d8cce1a5) [ 193.100493][ C0] stack guard page: 0000 [#1] SMP PTI [ 193.100499][ C0] CPU: 0 PID: 968 Comm: a.out Not tainted 5.14.0-next-20210913+ #548 [ 193.100506][ C0] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011 [ 193.100510][ C0] RIP: 0010:perf_swevent_get_recursion_context+0x0/0x70 [ 193.100523][ C0] Code: 48 03 43 28 48 8b 0c 24 bb 01 00 00 00 4c 29 f0 48 39 c8 48 0f 47 c1 49 89 45 08 e9 48 ff ff ff 66 2e 0f 1f 84 00 00 00 00 00 <55> 53 e8 09 20 f2 ff 48 c7 c2 20 4d 03 00 65 48 03 15 5a 3b d2 7e [ 193.100529][ C0] RSP: 0018:fffffe000000b000 EFLAGS: 00010046 [ 193.100535][ C0] RAX: 0000000080120006 RBX: fffffe000000b050 RCX: 0000000000000000 [ 193.100540][ C0] RDX: ffff88810de82180 RSI: ffffffff81269031 RDI: 000000000000001c [ 193.100544][ C0] RBP: 000000000000001c R08: 0000000000000001 R09: 0000000000000000 [ 193.100548][ C0] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 [ 193.100551][ C0] R13: fffffe000000b044 R14: 0000000000000001 R15: 0000000000000009 [ 193.100556][ C0] FS: 00007fa18c42d740(0000) GS:ffff88813bc00000(0000) knlGS:0000000000000000 [ 193.100562][ C0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 193.100566][ C0] CR2: fffffe000000aff8 CR3: 00000001160ac005 CR4: 00000000003606f0 [ 193.100570][ C0] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 193.100574][ C0] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 193.100578][ C0] Call Trace: [ 193.100581][ C0] [ 193.100584][ C0] perf_trace_buf_alloc+0x26/0xd0 [ 193.100597][ C0] ? is_prefetch.isra.25+0x260/0x260 [ 193.100605][ C0] ? __bad_area_nosemaphore+0x1b8/0x280 [ 193.100611][ C0] perf_ftrace_function_call+0x18f/0x2e0 Tested-by: Michael Wang BTW, would you like to apply the other patch which increasing exception stack size after this one? Regards, Michael Wang > > --- > diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h > index 562854c60808..9a2e37a7304d 100644 > --- a/arch/x86/include/asm/irq_stack.h > +++ b/arch/x86/include/asm/irq_stack.h > @@ -77,11 +77,11 @@ > * Function calls can clobber anything except the callee-saved > * registers. Tell the compiler. > */ > -#define call_on_irqstack(func, asm_call, argconstr...) \ > +#define call_on_stack(stack, func, asm_call, argconstr...) \ > { \ > register void *tos asm("r11"); \ > \ > - tos = ((void *)__this_cpu_read(hardirq_stack_ptr)); \ > + tos = ((void *)(stack)); \ > \ > asm_inline volatile( \ > "movq %%rsp, (%[tos]) \n" \ > @@ -98,6 +98,25 @@ > ); \ > } > > +#define ASM_CALL_ARG0 \ > + "call %P[__func] \n" > + > +#define ASM_CALL_ARG1 \ > + "movq %[arg1], %%rdi \n" \ > + ASM_CALL_ARG0 > + > +#define ASM_CALL_ARG2 \ > + "movq %[arg2], %%rsi \n" \ > + ASM_CALL_ARG1 > + > +#define ASM_CALL_ARG3 \ > + "movq %[arg3], %%rdx \n" \ > + ASM_CALL_ARG2 > + > +#define call_on_irqstack(func, asm_call, argconstr...) \ > + call_on_stack(__this_cpu_read(hardirq_stack_ptr), \ > + func, asm_call, argconstr) > + > /* Macros to assert type correctness for run_*_on_irqstack macros */ > #define assert_function_type(func, proto) \ > static_assert(__builtin_types_compatible_p(typeof(&func), proto)) > @@ -147,8 +166,7 @@ > */ > #define ASM_CALL_SYSVEC \ > "call irq_enter_rcu \n" \ > - "movq %[arg1], %%rdi \n" \ > - "call %P[__func] \n" \ > + ASM_CALL_ARG1 \ > "call irq_exit_rcu \n" > > #define SYSVEC_CONSTRAINTS , [arg1] "r" (regs) > @@ -168,12 +186,10 @@ > */ > #define ASM_CALL_IRQ \ > "call irq_enter_rcu \n" \ > - "movq %[arg1], %%rdi \n" \ > - "movl %[arg2], %%esi \n" \ > - "call %P[__func] \n" \ > + ASM_CALL_ARG2 \ > "call irq_exit_rcu \n" > > -#define IRQ_CONSTRAINTS , [arg1] "r" (regs), [arg2] "r" (vector) > +#define IRQ_CONSTRAINTS , [arg1] "r" (regs), [arg2] "r" ((long)vector) > > #define run_irq_on_irqstack_cond(func, regs, vector) \ > { \ > @@ -185,9 +201,6 @@ > IRQ_CONSTRAINTS, regs, vector); \ > } > > -#define ASM_CALL_SOFTIRQ \ > - "call %P[__func] \n" > - > /* > * Macro to invoke __do_softirq on the irq stack. This is only called from > * task context when bottom halves are about to be reenabled and soft > @@ -197,7 +210,7 @@ > #define do_softirq_own_stack() \ > { \ > __this_cpu_write(hardirq_stack_inuse, true); \ > - call_on_irqstack(__do_softirq, ASM_CALL_SOFTIRQ); \ > + call_on_irqstack(__do_softirq, ASM_CALL_ARG0); \ > __this_cpu_write(hardirq_stack_inuse, false); \ > } > > diff --git a/arch/x86/include/asm/stacktrace.h b/arch/x86/include/asm/stacktrace.h > index f248eb2ac2d4..17a52793f6c3 100644 > --- a/arch/x86/include/asm/stacktrace.h > +++ b/arch/x86/include/asm/stacktrace.h > @@ -38,6 +38,16 @@ int get_stack_info(unsigned long *stack, struct task_struct *task, > bool get_stack_info_noinstr(unsigned long *stack, struct task_struct *task, > struct stack_info *info); > > +static __always_inline > +bool get_stack_guard_info(unsigned long *stack, struct stack_info *info) > +{ > + /* make sure it's not in the stack proper */ > + if (get_stack_info_noinstr(stack, current, info)) > + return false; > + /* but if it is in the page below it, we hit a guard */ > + return get_stack_info_noinstr((void *)stack + PAGE_SIZE-1, current, info); > +} > + > const char *stack_type_name(enum stack_type type); > > static inline bool on_stack(struct stack_info *info, void *addr, size_t len) > diff --git a/arch/x86/include/asm/traps.h b/arch/x86/include/asm/traps.h > index 7f7200021bd1..6221be7cafc3 100644 > --- a/arch/x86/include/asm/traps.h > +++ b/arch/x86/include/asm/traps.h > @@ -40,9 +40,9 @@ void math_emulate(struct math_emu_info *); > bool fault_in_kernel_space(unsigned long address); > > #ifdef CONFIG_VMAP_STACK > -void __noreturn handle_stack_overflow(const char *message, > - struct pt_regs *regs, > - unsigned long fault_address); > +void __noreturn handle_stack_overflow(struct pt_regs *regs, > + unsigned long fault_address, > + struct stack_info *info); > #endif > > #endif /* _ASM_X86_TRAPS_H */ > diff --git a/arch/x86/kernel/dumpstack_64.c b/arch/x86/kernel/dumpstack_64.c > index 5601b95944fa..6c5defd6569a 100644 > --- a/arch/x86/kernel/dumpstack_64.c > +++ b/arch/x86/kernel/dumpstack_64.c > @@ -32,9 +32,15 @@ const char *stack_type_name(enum stack_type type) > { > BUILD_BUG_ON(N_EXCEPTION_STACKS != 6); > > + if (type == STACK_TYPE_TASK) > + return "TASK"; > + > if (type == STACK_TYPE_IRQ) > return "IRQ"; > > + if (type == STACK_TYPE_SOFTIRQ) > + return "SOFTIRQ"; > + > if (type == STACK_TYPE_ENTRY) { > /* > * On 64-bit, we have a generic entry stack that we > diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c > index a58800973aed..77857d41289d 100644 > --- a/arch/x86/kernel/traps.c > +++ b/arch/x86/kernel/traps.c > @@ -313,17 +313,19 @@ DEFINE_IDTENTRY_ERRORCODE(exc_alignment_check) > } > > #ifdef CONFIG_VMAP_STACK > -__visible void __noreturn handle_stack_overflow(const char *message, > - struct pt_regs *regs, > - unsigned long fault_address) > +__visible void __noreturn handle_stack_overflow(struct pt_regs *regs, > + unsigned long fault_address, > + struct stack_info *info) > { > - printk(KERN_EMERG "BUG: stack guard page was hit at %p (stack is %p..%p)\n", > - (void *)fault_address, current->stack, > - (char *)current->stack + THREAD_SIZE - 1); > - die(message, regs, 0); > + const char *name = stack_type_name(info->type); > + > + printk(KERN_EMERG "BUG: %s stack guard page was hit at %p (stack is %p..%p)\n", > + name, (void *)fault_address, info->begin, info->end); > + > + die("stack guard page", regs, 0); > > /* Be absolutely certain we don't return. */ > - panic("%s", message); > + panic("%s stack guard hit", name); > } > #endif > > @@ -353,6 +355,7 @@ DEFINE_IDTENTRY_DF(exc_double_fault) > > #ifdef CONFIG_VMAP_STACK > unsigned long address = read_cr2(); > + struct stack_info info; > #endif > > #ifdef CONFIG_X86_ESPFIX64 > @@ -455,10 +458,8 @@ DEFINE_IDTENTRY_DF(exc_double_fault) > * stack even if the actual trigger for the double fault was > * something else. > */ > - if ((unsigned long)task_stack_page(tsk) - 1 - address < PAGE_SIZE) { > - handle_stack_overflow("kernel stack overflow (double-fault)", > - regs, address); > - } > + if (get_stack_guard_info((void *)address, &info)) > + handle_stack_overflow(regs, address, &info); > #endif > > pr_emerg("PANIC: double fault, error_code: 0x%lx\n", error_code); > diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c > index b2eefdefc108..edb5152f0866 100644 > --- a/arch/x86/mm/fault.c > +++ b/arch/x86/mm/fault.c > @@ -32,6 +32,7 @@ > #include /* VMALLOC_START, ... */ > #include /* kvm_handle_async_pf */ > #include /* fixup_vdso_exception() */ > +#include > > #define CREATE_TRACE_POINTS > #include > @@ -631,6 +632,9 @@ static noinline void > page_fault_oops(struct pt_regs *regs, unsigned long error_code, > unsigned long address) > { > +#ifdef CONFIG_VMAP_STACK > + struct stack_info info; > +#endif > unsigned long flags; > int sig; > > @@ -649,9 +653,7 @@ page_fault_oops(struct pt_regs *regs, unsigned long error_code, > * that we're in vmalloc space to avoid this. > */ > if (is_vmalloc_addr((void *)address) && > - (((unsigned long)current->stack - 1 - address < PAGE_SIZE) || > - address - ((unsigned long)current->stack + THREAD_SIZE) < PAGE_SIZE)) { > - unsigned long stack = __this_cpu_ist_top_va(DF) - sizeof(void *); > + get_stack_guard_info((void *)address, &info)) { > /* > * We're likely to be running with very little stack space > * left. It's plausible that we'd hit this condition but > @@ -662,13 +664,11 @@ page_fault_oops(struct pt_regs *regs, unsigned long error_code, > * and then double-fault, though, because we're likely to > * break the console driver and lose most of the stack dump. > */ > - asm volatile ("movq %[stack], %%rsp\n\t" > - "call handle_stack_overflow\n\t" > - "1: jmp 1b" > - : ASM_CALL_CONSTRAINT > - : "D" ("kernel stack overflow (page fault)"), > - "S" (regs), "d" (address), > - [stack] "rm" (stack)); > + call_on_stack(__this_cpu_ist_top_va(DF) - sizeof(void*), > + handle_stack_overflow, > + ASM_CALL_ARG3, > + , [arg1] "r" (regs), [arg2] "r" (address), [arg3] "r" (&info)); > + > unreachable(); > } > #endif >