On Wed, Aug 14, 2024 at 9:44 AM <devel-request@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
Date: Wed, 14 Aug 2024 11:25:24 +1200
From: Tao Liu <ltao@xxxxxxxxxx>
Subject: [PATCH v2] Fix a segfault issue due to the
incorrect irq_stack_size on ARM64
To: devel@xxxxxxxxxxxxxxxxxxxxxxxxxxx
Cc: "yeping . zheng" <yeping.zheng@xxxxxxx>
Message-ID: <20240813232523.7237-1-ltao@xxxxxxxxxx>
Content-Type: text/plain; charset="US-ASCII"; x-default=true
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="" 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. 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.
2. 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>
Signed-off-by: yeping.zheng <yeping.zheng@xxxxxxx>
Improved-by: Tao Liu <ltao@xxxxxxxxxx>
---
v2 -> v1: Add stack_vm_area member check for task_struct, and kernel
file reference.
Hi Yeping & lianbo,
Please have a test on this version of patch, I guess this will be the
last version if test is passed. Thanks in advance!
Thank you for working on it, Yeping and Tao.
This looks good to me. Applied:
Thanks
Lianbo
Thanks,
Tao Liu
---
arm64.c | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 61 insertions(+), 2 deletions(-)
diff --git a/arm64.c b/arm64.c
index 067c879..332e3f0 100644
--- a/arm64.c
+++ b/arm64.c
@@ -95,6 +95,7 @@ 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;
@@ -2340,8 +2341,10 @@ 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;
@@ -5056,6 +5059,62 @@ 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;
+
+ if (kernel_symbol_exists("vmcoreinfo_data") &&
+ kernel_symbol_exists("vmcoreinfo_size")) {
+ /*
+ * Referring to arch/arm64/include/asm/memory.h
+ */
+ if (kernel_symbol_exists("kasan_enable_current")) {
+ min_thread_shift += 1;
+ }
+ if (MEMBER_EXISTS("task_struct", "stack_vm_area") &&
+ min_thread_shift < machdep->pageshift) {
+ thread_shift = machdep->pageshift;
+ } else {
+ thread_shift = min_thread_shift;
+ }
+ } else {
+ 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)
+ return ((1UL) << thread_shift);
+ else
+ return 0;
+}
+
#endif /* ARM64 */
--
2.40.1
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