Hi Lianbo,
> Hi, sending a patch as attachment is bad, you can refer to the kernel
doc:
Thank to Dave for pointing that out. I apologize for not realizing this
before, and resend it as following.
> I think you are right, the else branch can work well regardless of
whether vmcoreinfo is present or not. So I changed the execution order of
the code:
> Step 1. Try to get THREAD_SHIFT from tbnz instruction.
> Step 2. If cannot get THREAD_SHIFT by step 1, change the thread_shift
when KASAN is enabled and with vmcoreinfo.
> Please help review this new patch.
---
arm64.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 47 insertions(+), 2 deletions(-)
diff --git a/arm64.c b/arm64.c
index 78e6609..49799e6 100644
--- a/arm64.c
+++ b/arm64.c
@@ -94,6 +94,7 @@ static int arm64_is_uvaddr(ulong, struct task_context *);
static void arm64_calc_KERNELPACMASK(void);
static void arm64_recalc_KERNELPACMASK(void);
static int arm64_get_vmcoreinfo(unsigned long *vaddr, const char *label,
int base);
+static ulong arm64_set_irq_stack_size(void);
struct kernel_range {
unsigned long modules_vaddr, modules_end;
@@ -2234,8 +2235,10 @@ 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->irq_stack_size = (res > 0) ? res :
ARM64_IRQ_STACK_SIZE;
+ }
machdep->flags |= IRQ_STACKS;
@@ -4950,6 +4953,48 @@ static void arm64_recalc_KERNELPACMASK(void){
}
}
+static ulong arm64_set_irq_stack_size(void)
+{
+ int min_thread_shift = 14;
+ ulong thread_shift = 0;
+ char buf1[BUFSIZE];
+ char *pos1, *pos2;
+ int errflag = 0;
+
+ sprintf(buf1, "x/32i vectors");
+ open_tmpfile();
+ if (!gdb_pass_through(buf1, pc->tmpfile, GNU_RETURN_ON_ERROR)) {
+ goto out;
+ }
+ rewind(pc->tmpfile);
+ while (fgets(buf1, BUFSIZE, pc->tmpfile)) {
+ if ((pos1 = strstr(buf1, "tbnz"))) {
+ if ((pos2 = strchr(pos1, '#'))) {
+ pos2 += 1;
+ for(pos1=pos2; *pos2!='\0' && *pos2!=',';
pos2++);
+ *pos2 = '\0';
+ thread_shift = stol(pos1,
RETURN_ON_ERROR|QUIET, &errflag);
+ if (errflag) {
+ thread_shift = 0;
+ }
+ break;
+ }
+ }
+ }
+out:
+ close_tmpfile();
+
+ if ((!thread_shift) &&
kernel_symbol_exists("kasan_enable_current")) {
+ min_thread_shift += 1;
+ thread_shift = (min_thread_shift < machdep->pageshift) ?
machdep->pageshift : min_thread_shift;
+ }
+
+ if (!thread_shift)
+ return 0;
+ else
+ return ((1UL) << thread_shift);
+}
+
#endif /* ARM64 */
Thanks
yeping.
Dave Young <[email protected]> 于2024年7月31日周三 14:58写道：
> > Please help review this new patch.
>
> Hi, sending a patch as attachment is bad, you can refer to the kernel doc:
> https://www.kernel.org/doc/html/v4.14/process/email-clients.html
>
> "Patches for the Linux kernel are submitted via email, preferably as
> inline text in the body of the email. Some maintainers accept
> attachments, but then the attachments should have content-type
> text/plain. However, attachments are generally frowned upon because it
> makes quoting portions of the patch more difficult in the patch review
> process."
>
> Crash is different from kernel but the email process is similar, I
> think you can resend it with a proper format instead of maintainers
> manually copying them in the email body for review.
>
> Thanks
> Dave
>
>
From 2e4d11da6db27952a5bcfd7e3475bd42d230f6b8 Mon Sep 17 00:00:00 2001
From: "yeping.zheng" <[email protected]>
Date: Tue, 30 Jul 2024 14:16:54 +0800
Subject: [PATCH] A segfault issue due to the incorrect irq_stack_size on ARM64
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 may be encountered when thread_union symbol not found in vmlinux
due to compiling optimization.
This patch will try the following 2 methods to get the irq_stack_size
when thread_union symbol unavailable:
1. Try getting the value from kernel code disassembly, to get
THREAD_SHIFT directly from tbnz instruction.
In arch/arm64/kernel/entry.S:
.macro kernel_ventry, el:req, ht:req, regsize:req, label:req
...
add sp, sp, x0
sub x0, sp, x0
tbnz x0, #THREAD_SHIFT, 0f
$ gdb vmlinux
(gdb) disass vectors
Dump of assembler code for function vectors:
...
0xffff800080010804 <+4>: add sp, sp, x0
0xffff800080010808 <+8>: sub x0, sp, x0
0xffff80008001080c <+12>: tbnz w0, #16, 0xffff80008001081c <vectors+28>
2. If cannot get THREAD_SHIFT by step 1, change the thread_shift when KASAN is enabled and with vmcoreinfo.
In arm64/include/asm/memory.h:
#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
...
#define IRQ_STACK_SIZE THREAD_SIZE
Since enabling the KASAN will affect the final value,
this patch reset IRQ_STACK_SIZE according to the calculation process in kernel code.
Signed-off-by: yeping.zheng <yeping.zheng(a)nio.com>
---
arm64.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 47 insertions(+), 2 deletions(-)
diff --git a/arm64.c b/arm64.c
index 78e6609..49799e6 100644
--- a/arm64.c
+++ b/arm64.c
@@ -94,6 +94,7 @@ static int arm64_is_uvaddr(ulong, struct task_context *);
static void arm64_calc_KERNELPACMASK(void);
static void arm64_recalc_KERNELPACMASK(void);
static int arm64_get_vmcoreinfo(unsigned long *vaddr, const char *label, int base);
+static ulong arm64_set_irq_stack_size(void);
struct kernel_range {
unsigned long modules_vaddr, modules_end;
@@ -2234,8 +2235,10 @@ 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->irq_stack_size = (res > 0) ? res : ARM64_IRQ_STACK_SIZE;
+ }
machdep->flags |= IRQ_STACKS;
@@ -4950,6 +4953,48 @@ static void arm64_recalc_KERNELPACMASK(void){
}
}
+static ulong arm64_set_irq_stack_size(void)
+{
+ int min_thread_shift = 14;
+ ulong thread_shift = 0;
+ char buf1[BUFSIZE];
+ char *pos1, *pos2;
+ int errflag = 0;
+
+ sprintf(buf1, "x/32i vectors");
+ open_tmpfile();
+ if (!gdb_pass_through(buf1, pc->tmpfile, GNU_RETURN_ON_ERROR)) {
+ goto out;
+ }
+ rewind(pc->tmpfile);
+ while (fgets(buf1, BUFSIZE, pc->tmpfile)) {
+ if ((pos1 = strstr(buf1, "tbnz"))) {
+ if ((pos2 = strchr(pos1, '#'))) {
+ pos2 += 1;
+ for(pos1=pos2; *pos2!='\0' && *pos2!=','; pos2++);
+ *pos2 = '\0';
+ thread_shift = stol(pos1, RETURN_ON_ERROR|QUIET, &errflag);
+ if (errflag) {
+ thread_shift = 0;
+ }
+ break;
+ }
+ }
+ }
+out:
+ close_tmpfile();
+
+ if ((!thread_shift) && kernel_symbol_exists("kasan_enable_current")) {
+ min_thread_shift += 1;
+ thread_shift = (min_thread_shift < machdep->pageshift) ? machdep->pageshift : min_thread_shift;
+ }
+
+ if (!thread_shift)
+ return 0;
+ else
+ return ((1UL) << thread_shift);
+}
+
#endif /* ARM64 */
--
2.25.1
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