7:49 p.m.
Hello list,
When i try to use gcore to parse coredump from fulldump,I got below issue that make the
coredump unavailable.
1. Zram is very common feature,in current android system supports zram swap,but
gcore/crash-utility does not support,even zram swap can decoded from ram,many page fault
due to this reason.
I added zram decompress feature to gcore,and i’m also considering wheather support zram in
crash-utility,but for this feature,i have to add miniLZO to codebase, I'm not sure if
it's acceptable,plase help give some advice.
miniLZO :miniLZO is a very lightweight subset of the LZO library,Distributed under the
terms of the GNU General Public
License<http://www.oberhumer.com/opensource/gpl.html> (GPL v2+).
http://www.oberhumer.com/opensource/lzo/
This change is a bit big,I attached it to the mail,if attachment is not available,you can
also see these patch in github:
https://github.com/zhaoqianli0202/crash-gcore/commits/upstream
Please review.
2. For historical reasons,kernel reserved top 8/16 bytes of stacks,but after
kernel-4.14, this reservation was cancelled,so gcore needs to improve compatibility.
kernel change as below:
commit 34be98f4944f99076f049a6806fc5f5207a755d3
Author: Ard Biesheuvel
<ard.biesheuvel@linaro.org<mailto:ard.biesheuvel@linaro.org>>
Date: Thu Jul 20 17:15:45 2017 +0100
arm64: kernel: remove {THREAD,IRQ_STACK}_START_SP
For historical reasons, we leave the top 16 bytes of our task and IRQ
stacks unused, a practice used to ensure that the SP can always be
masked to find the base of the current stack (historically, where
thread_info could be found).™
====
Patch for this issue:
commit d1031df4617351a58b8edfb0121c306baaa34f9d
Author: zhaoqianli <zhaoqianli(a)xiaomi.com>
Date: Mon Mar 30 12:07:02 2020 +0800
gcore: ARM/ARM64 reserved 8/16 byte in the top of stacks before 4.14,
but this reservation was removed after 4.14
Without this patch,gcore counld't parse full callstack in version after 4.14
diff --git a/gcore.c b/gcore.c
index f75701d..f6e1787 100644
--- a/gcore.c
+++ b/gcore.c
@@ -558,4 +558,16 @@ static void gcore_machdep_init(void)
if (!gcore_arch_vsyscall_has_vm_alwaysdump_flag())
gcore_machdep->vm_alwaysdump = 0x00000000;
+
+#if defined(ARM) || defined(ARM64)
+#ifdef ARM
+#define STACK_RESERVE_SIZE 8
+#else
+#define STACK_RESERVE_SIZE 16
+#endif
+ if (THIS_KERNEL_VERSION >= LINUX(4,14,0))
+ gcore_machdep->stack_reserve = 0;
+ else
+ gcore_machdep->stack_reserve = STACK_RESERVE_SIZE;
+#endif
}
diff --git a/libgcore/gcore_arm.c b/libgcore/gcore_arm.c
index 891d01e..c8aefdf 100644
--- a/libgcore/gcore_arm.c
+++ b/libgcore/gcore_arm.c
@@ -29,7 +29,7 @@ static int gpr_get(struct task_context *target,
BZERO(regs, sizeof(*regs));
- readmem(machdep->get_stacktop(target->task) - 8 - SIZE(pt_regs), KVADDR,
+ readmem(machdep->get_stacktop(target->task) -
gcore_machdep->stack_reserve - SIZE(pt_regs), KVADDR,
regs, SIZE(pt_regs), "genregs_get: pt_regs",
gcore_verbose_error_handle());
diff --git a/libgcore/gcore_arm64.c b/libgcore/gcore_arm64.c
index 3257389..ed3fdc8 100644
--- a/libgcore/gcore_arm64.c
+++ b/libgcore/gcore_arm64.c
@@ -28,7 +28,7 @@ static int gpr_get(struct task_context *target,
BZERO(regs, sizeof(*regs));
- readmem(machdep->get_stacktop(target->task) - 16 - SIZE(pt_regs), KVADDR,
+ readmem(machdep->get_stacktop(target->task) -
gcore_machdep->stack_reserve - SIZE(pt_regs), KVADDR,
regs, sizeof(struct user_pt_regs), "gpr_get: user_pt_regs",
gcore_verbose_error_handle());
@@ -124,7 +124,7 @@ static int compat_gpr_get(struct task_context *target,
BZERO(&pt_regs, sizeof(pt_regs));
BZERO(regs, sizeof(*regs));
- readmem(machdep->get_stacktop(target->task) - 16 - SIZE(pt_regs), KVADDR,
+ readmem(machdep->get_stacktop(target->task) -
gcore_machdep->stack_reserve - SIZE(pt_regs), KVADDR,
&pt_regs, sizeof(struct pt_regs), "compat_gpr_get:
pt_regs",
gcore_verbose_error_handle());
diff --git a/libgcore/gcore_defs.h b/libgcore/gcore_defs.h
index b0f5603..f31036c 100644
--- a/libgcore/gcore_defs.h
+++ b/libgcore/gcore_defs.h
@@ -1177,6 +1177,7 @@ extern struct gcore_size_table gcore_size_table;
struct gcore_machdep_table
{
ulong vm_alwaysdump;
+ uint8_t stack_reserve;
};
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