On Fri, Jul 19, 2024 at 6:40 AM Tao Liu <l...@redhat.com> wrote: > Hi Lianbo, > > On Thu, Jul 18, 2024 at 10:50 PM Lianbo Jiang <liji...@redhat.com> wrote: > > > > On 7/16/24 4:22 PM, Tao Liu wrote: > > > > > Hi Yeping, > > > > > > Thanks for the fix. > > > > > > On Thu, Jul 11, 2024 at 1:38 PM <wonder...@gmail.com> 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 <wonder...@qq.com> > > >> Date: Mon, 8 Jul 2024 20:11:38 +0800 > > >> Subject: [PATCH 1131/1131] set_arm64_irq_stack_size > > >> > > >> Signed-off-by: Yeping Zheng <wonder...@gmail.com> > > >> --- > > >> 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)) == > > > > The "CONFIG_ARM64_PAGE_SHIFT " has been removed since kernel v6.9-rc1, > > so this can not work on the latest kernel. See: > > > > d3e5bab923d3 ("arch: simplify architecture specific page size > > configuration") > > > > > > In addition, the IKCONFIG is not available in most distributions, it > > can not cover this case. There is a similar discussion there: > > > > > https://www.mail-archive.com/devel@lists.crash-utility.osci.io/msg00880.html > > > > Can you try to handle the current issue with a similar solution? > > > > > > >> 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 > > > > This is a good idea, but it still relies on compiler. > > > > As we discussed, usually I would recommend finding its values via some > > kernel symbols. > > Yeah, but I didn't find a suitable symbol so far... In addition, the >
It's true. For the KASAN, it is easy to find a suitable symbol, but it's not easy for the PAGESIZE or PAGESHIFT. Given that I would suggest covering two cases: [1] with vmcoreinfo(see mm/kasan/common.c) ... int min_thread_shift = 14; if (kernel_symbol_exists("kasan_enable_current")) min_thread_shift += 1; thread_shift = (min_thread_shift < machdep->pageshift) ? machdep->pageshift : min_thread_shift; ... [2] without vmcoreinfo Use Tao's solution(disassemble kernel code) The first one is better than the second one in case of having vmcoreinfo, If I understand correctly. But we still need to cover the above two cases in the crash tools. BTW: can you help point out the current issue is with or without the vmcoreinfo? Yeping Thanks Lianbo above case is a little different here, the tbnz instruction is not > generated from C code, it is written in assembly in > arch/arm64/kernel/entry.S file. So I guess there would be a lower > possibility if tbnz instruction gets replaced or eliminated by the > compilers. Anyway, it's OK to me if you don't want to accept the > approach. > > Thanks, > Tao Liu > > > > > > > > Thanks > > > > Lianbo > > > > > > > > Thanks, > > > Tao Liu > > > > > >> + > > >> #endif /* ARM64 */ > > >> > > >> > > >> -- > > >> 2.25.1 > > >> > > > >
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