[Crash-utility] Re: Fix irq_stack_size on ARM64

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