Hi Yeping,
Thanks for the fix.
On Thu, Jul 11, 2024 at 1:38 PM <wonderzyp@xxxxxxxxx> 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@xxxxxx>
> Date: Mon, 8 Jul 2024 20:11:38 +0800
> Subject: [PATCH 1131/1131] set_arm64_irq_stack_size
>
> Signed-off-by: Yeping Zheng <wonderzyp@xxxxxxxxx>
> ---
> 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
> --
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