[Crash-utility] Re: Fix irq_stack_size on ARM64

Hi Tao, Thank you for your suggestions for patch. I followed your suggestion and provided a new patch. Please help to review it, thanks. From 831701099a7097662ddec9de464131ad50c7134b Mon Sep 17 00:00:00 2001 From: wonderzyp <wonderzyp(a)qq.com&gt; Date: Wed, 17 Jul 2024 11:02:06 +0800 Subject: [PATCH] A segfault issue was observed on KASAN enabled arm64 kernel due to the incorrect irq_stack_size, see the following stack trace: > (gdb) bt > #0 0x00005635ac2b166b in arm64_unwind_frame (frame=0x7ffdaf35cb70, bt=0x7ffdaf35d430) > at arm64.c:2821 > #1 arm64_back_trace_cmd (bt=0x7ffdaf35d430) at arm64.c:3306 > #2 0x00005635ac27b108 in back_trace (bt=bt@entry=0x7ffdaf35d430) at kernel.c:3239 > #3 0x00005635ac2880ae in cmd_bt () at kernel.c:2863 > #4 0x00005635ac1f16dc in exec_command () at main.c:893 > #5 0x00005635ac1f192a in main_loop () at main.c:840 > #6 0x00005635ac50df81 in captured_main (data=<optimized out>) at main.c:1284 > #7 gdb_main (args=<optimized out>) at main.c:1313 > #8 0x00005635ac50e000 in gdb_main_entry (argc=<optimized out>, argv=<optimized out>) > at main.c:1338 > #9 0x00005635ac1ea2a5 in main (argc=5, argv=0x7ffdaf35dde8) at main.c:721 The issue was caused by not setting irq_stack_size correctly, and this patch will fix the issue by two ways: 1. if CONFIG_IKCONFIG is set, calculate the irq_stack_size according to kernel source code 2. if CONFIG_IKCONFIG is not set, get THREAD_SHIFT value by disassembling the tbnz instruction to calculate the irq_stack_size Signed-off-by: Yeping.Zheng <yeping.zheng(a)nio.com&gt; --- arm64.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 84 insertions(+), 2 deletions(-) diff --git a/arm64.c b/arm64.c index b3040d7..8347ba1 100644 --- a/arm64.c +++ b/arm64.c @@ -93,6 +93,7 @@ static void arm64_calc_VA_BITS(void); static int arm64_is_uvaddr(ulong, struct task_context *); static void arm64_calc_KERNELPACMASK(void); static int arm64_get_vmcoreinfo(unsigned long *vaddr, const char *label, int base); +static ulong arm64_set_irq_stack_size(struct machine_specific *ms); struct kernel_range { unsigned long modules_vaddr, modules_end; @@ -2223,8 +2224,10 @@ arm64_irq_stack_init(void) if (MEMBER_EXISTS("thread_union", "stack")) { if ((sz = MEMBER_SIZE("thread_union", "stack")) > 0) ms->irq_stack_size = sz; - } else - ms->irq_stack_size = ARM64_IRQ_STACK_SIZE; + } else { + ulong res = arm64_set_irq_stack_size(ms); + ms->irq_stack_size = (res > 0) ? res : ARM64_IRQ_STACK_SIZE; + } machdep->flags |= IRQ_STACKS; @@ -4921,6 +4924,85 @@ static void arm64_calc_KERNELPACMASK(void) } } +static ulong arm64_set_irq_stack_size(struct machine_specific *ms) +{ + char *string; + int ret; + int kasan_thread_shift = 0; + int min_thread_shift; + ulong arm64_page_shift; + ulong thread_shift = 0; + ulong thread_size; + struct syment *sp; + const char* tbnz_str = "tbnz"; + + if (kt->ikconfig_flags & IKCONFIG_AVAIL) { + if ((ret = get_kernel_config("CONFIG_KASAN_GENERIC", NULL) == IKCONFIG_Y) || + (ret = get_kernel_config("CONFIG_KASAN_SW_TAGS", NULL) == IKCONFIG_Y)) { + kasan_thread_shift = 1; + } + min_thread_shift = 14 + kasan_thread_shift; + + if ((ret = get_kernel_config("CONFIG_VMAP_STACK", NULL)) == IKCONFIG_Y){ + if ((ret = get_kernel_config("CONFIG_ARM64_PAGE_SHIFT", &string)) == IKCONFIG_STR){ + arm64_page_shift = atol(string); + } + if (min_thread_shift < arm64_page_shift){ + thread_shift = arm64_page_shift; + } else { + thread_shift = min_thread_shift; + } + } + } else { + + if (!(sp = symbol_search("vectors"))) { + return -1; + } + + const char* tbnz_str = "tbnz"; + struct gnu_request *req; + req = (struct gnu_request *)GETBUF(sizeof(struct gnu_request)); + req->command = GNU_PASS_THROUGH; + req->buf = GETBUF(BUFSIZE); + strcat(req->buf, "x/1024i "); + + char tmp[100]; + sprintf(tmp, "0x%lx", sp->value); + strcat(req->buf, tmp); + req->flags = (GNU_RETURN_ON_ERROR); + open_tmpfile(); + req->fp = pc->tmpfile; + gdb_interface(req); + + + rewind(pc->tmpfile); + char line[BUFSIZE]; + while (fgets(line, BUFSIZE, pc->tmpfile) != NULL) { + // printf("the buffer is not null\n"); + char* tbnz_pos = strstr(line, tbnz_str); + if (tbnz_pos != NULL) { + char* thread_shift_pos = strstr(tbnz_pos, "#"); + if (sscanf(thread_shift_pos + 1, "%ld", &thread_shift) == 1) { + if (CRASHDEBUG(1)){ + error(INFO, "Detect thread shift via tbnz %ld\n", thread_shift); + } + break; + } + } + } + close_tmpfile(); + FREEBUF(req->buf); + FREEBUF(req); + } + + if (thread_shift == 0) { + return -1; + } + + thread_size = ((1UL) << thread_shift); + return thread_size; +} + #endif /* ARM64 */ -- 2.25.1 Tao Liu <ltao(a)redhat.com&gt; 于2024年7月16日周二 16:22写道： > > Hi Yeping, > > Thanks for the fix. > > On Thu, Jul 11, 2024 at 1:38 PM <wonderzyp(a)gmail.com&gt; wrote: > > > > When using the crash tool to parse the ARM64 dump file with KASAN enabled, I found that using the bt -a command will cause this tool to crash, the following is the backtrace infomation. > > > > (gdb) bt > > #0 0x00005635ac2b166b in arm64_unwind_frame (frame=0x7ffdaf35cb70, bt=0x7ffdaf35d430) > > at arm64.c:2821 > > #1 arm64_back_trace_cmd (bt=0x7ffdaf35d430) at arm64.c:3306 > > #2 0x00005635ac27b108 in back_trace (bt=bt@entry=0x7ffdaf35d430) at kernel.c:3239 > > #3 0x00005635ac2880ae in cmd_bt () at kernel.c:2863 > > #4 0x00005635ac1f16dc in exec_command () at main.c:893 > > #5 0x00005635ac1f192a in main_loop () at main.c:840 > > #6 0x00005635ac50df81 in captured_main (data=<optimized out>) at main.c:1284 > > #7 gdb_main (args=<optimized out>) at main.c:1313 > > #8 0x00005635ac50e000 in gdb_main_entry (argc=<optimized out>, argv=<optimized out>) > > at main.c:1338 > > #9 0x00005635ac1ea2a5 in main (argc=5, argv=0x7ffdaf35dde8) at main.c:721 > > Eventually, I found that it was may caused by not setting irq_stack_size properly, and provide this patch to solve it. > > > > Could you please re-draft your commit message? The original one looks > informal. E.g: > > A segfault issue was observed on KASAN enabled arm64 kernel due to the > incorrect irq_stack_size, see the following stack trace: > ... > The issue was caused by ...., and this patch will fix the issue by .... > > > > > From 34b28aa8c11e77d20adec4f7705a14d239c8a55f Mon Sep 17 00:00:00 2001 > > From: wonderzyp <wonderzyp(a)qq.com&gt; > > Date: Mon, 8 Jul 2024 20:11:38 +0800 > > Subject: [PATCH 1131/1131] set_arm64_irq_stack_size > > > > Signed-off-by: Yeping Zheng <wonderzyp(a)gmail.com&gt; > > --- > > arm64.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++-- > > 1 file changed, 47 insertions(+), 2 deletions(-) > > > > diff --git a/arm64.c b/arm64.c > > index b3040d7..39d891b 100644 > > --- a/arm64.c > > +++ b/arm64.c > > @@ -93,6 +93,7 @@ static void arm64_calc_VA_BITS(void); > > static int arm64_is_uvaddr(ulong, struct task_context *); > > static void arm64_calc_KERNELPACMASK(void); > > static int arm64_get_vmcoreinfo(unsigned long *vaddr, const char *label, int base); > > +static ulong arm64_set_irq_stack_size(struct machine_specific *ms); > > > > struct kernel_range { > > unsigned long modules_vaddr, modules_end; > > @@ -2223,8 +2224,14 @@ arm64_irq_stack_init(void) > > if (MEMBER_EXISTS("thread_union", "stack")) { > > if ((sz = MEMBER_SIZE("thread_union", "stack")) > 0) > > ms->irq_stack_size = sz; > > - } else > > - ms->irq_stack_size = ARM64_IRQ_STACK_SIZE; > > + } else { > > + ulong res = arm64_set_irq_stack_size(ms); > > + if (res > 0){ > > + ms->irq_stack_size = res; > > + } else { > > + ms->irq_stack_size = ARM64_IRQ_STACK_SIZE; > > + } > > + } > > > > machdep->flags |= IRQ_STACKS; > > > > @@ -4921,6 +4928,44 @@ static void arm64_calc_KERNELPACMASK(void) > > } > > } > > > > +static ulong arm64_set_irq_stack_size(struct machine_specific *ms) > > +{ > > + char *string; > > + int ret; > > + int KASAN_THREAD_SHIFT = 0; > > + int MIN_THREAD_SHIFT; > > + ulong ARM64_PAGE_SHIFT; > > + ulong THREAD_SHIFT = 0; > > + ulong THREAD_SIZE; > > I guess the upper case of variable names is not encouraged, though it > is the variable that comes from kernel config file. > > > + if (kt->ikconfig_flags & IKCONFIG_AVAIL) { > > + if ((ret = get_kernel_config("CONFIG_KASAN_GENERIC", NULL) == IKCONFIG_Y) || > > + (ret = get_kernel_config("CONFIG_KASAN_SW_TAGS", NULL) == IKCONFIG_Y)) { > > + KASAN_THREAD_SHIFT = 1; > > + } > > + } > > + MIN_THREAD_SHIFT = 14 + KASAN_THREAD_SHIFT; > > + > > + if (kt->ikconfig_flags & IKCONFIG_AVAIL) { > > Could the if condition be merged with the prior one? > > > + if ((ret = get_kernel_config("CONFIG_VMAP_STACK", NULL)) == IKCONFIG_Y){ > > + if ((ret = get_kernel_config("CONFIG_ARM64_PAGE_SHIFT", &string)) == IKCONFIG_STR){ > > + ARM64_PAGE_SHIFT = atol(string); > > + } > > + if (MIN_THREAD_SHIFT < ARM64_PAGE_SHIFT){ > > + THREAD_SHIFT = ARM64_PAGE_SHIFT; > > + } else { > > + THREAD_SHIFT = MIN_THREAD_SHIFT; > > + } > > + } > > + } > > + > > + if (THREAD_SHIFT == 0) { > > + return -1; > > + } > > + > > + THREAD_SIZE = ((1UL) << THREAD_SHIFT); > > + return THREAD_SIZE; > > +} > > I'm OK with the approach above, since it directly came from the kernel > source. However I'm not a fan of checking kernel configs, there might > be kernels which are compiled without CONFIG_IKCONFIG. > > Could we add an approach here, to get the value from disassembly when > CONFIG_IKCONFIG is negative? > > kernel source: arch/arm64/kernel/entry.S: > > .macro kernel_ventry, el:req, ht:req, regsize:req, label:req > .... > add sp, sp, x0 // sp' = sp + x0 > sub x0, sp, x0 // x0' = sp' - x0 = (sp + x0) - x0 = sp > tbnz x0, #THREAD_SHIFT, 0f <<<<<<<< > > $ objdump -d vmlinux > ... > ffff800080010800 <vectors>: > ffff800080010800: d10543ff sub sp, sp, #0x150 > ffff800080010804: 8b2063ff add sp, sp, x0 > ffff800080010808: cb2063e0 sub x0, sp, x0 > ffff80008001080c: 37800080 tbnz w0, #16, > ffff80008001081c <vectors+0x1c> <<<<<<<<<< > > It is easy to get the THREAD_SHIFT value by disassembling the tbnz > instruction. What do you think @Lianbo Jiang > > Thanks, > Tao Liu > > > + > > #endif /* ARM64 */ > > > > > > -- > > 2.25.1 > > -- > > Crash-utility mailing list -- devel(a)lists.crash-utility.osci.io > > To unsubscribe send an email to devel-leave(a)lists.crash-utility.osci.io > > https://${domain_name}/admin/lists/devel.lists.crash-utility.osci.io/ > > Contribution Guidelines: https://github.com/crash-utility/crash/wiki >