Re: [PATCH V3 1/2] RISC-V: Add arch_crash_save_vmcoreinfo support
From: Xianting Tian
Date: Tue Oct 18 2022 - 23:17:33 EST
在 2022/10/19 上午10:50, HAGIO KAZUHITO(萩尾 一仁) 写道:
On 2022/10/19 10:50, Xianting Tian wrote:
在 2022/10/18 下午6:03, Baoquan He 写道:
On 10/18/22 at 05:25pm, Xianting Tian wrote:
在 2022/10/18 下午5:10, Baoquan He 写道:
On 10/18/22 at 04:17pm, Xianting Tian wrote:
Add arch_crash_save_vmcoreinfo(), which exports VM layout(MODULES, VMALLOC,
VMEMMAP and KERNEL_LINK_ADDR ranges), va bits and ram base for vmcore.
Default pagetable levels and PAGE_OFFSET aren't same for different kernel
version as below. For pagetable levels, it sets sv57 by default and falls
back to setting sv48 at boot time if sv57 is not supported by the hardware.
For ram base, the default value is 0x80200000 for qemu riscv64 env and,
for example, is 0x200000 on the XuanTie 910 CPU.
* Linux Kernel 5.18 ~
* PGTABLE_LEVELS = 5
* PAGE_OFFSET = 0xff60000000000000
* Linux Kernel 5.17 ~
* PGTABLE_LEVELS = 4
* PAGE_OFFSET = 0xffffaf8000000000
* Linux Kernel 4.19 ~
* PGTABLE_LEVELS = 3
* PAGE_OFFSET = 0xffffffe000000000
Since these configurations change from time to time and version to version,
it is preferable to export them via vmcoreinfo than to change the crash's
code frequently, it can simplify the development of crash tool.
Signed-off-by: Xianting Tian <xianting.tian@xxxxxxxxxxxxxxxxx>
---
arch/riscv/kernel/Makefile | 1 +
arch/riscv/kernel/crash_core.c | 29 +++++++++++++++++++++++++++++
2 files changed, 30 insertions(+)
create mode 100644 arch/riscv/kernel/crash_core.c
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index db6e4b1294ba..4cf303a779ab 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -81,6 +81,7 @@ obj-$(CONFIG_KGDB) += kgdb.o
obj-$(CONFIG_KEXEC_CORE) += kexec_relocate.o crash_save_regs.o machine_kexec.o
obj-$(CONFIG_KEXEC_FILE) += elf_kexec.o machine_kexec_file.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
+obj-$(CONFIG_CRASH_CORE) += crash_core.o
obj-$(CONFIG_JUMP_LABEL) += jump_label.o
diff --git a/arch/riscv/kernel/crash_core.c b/arch/riscv/kernel/crash_core.c
new file mode 100644
index 000000000000..8d7f5ff108da
--- /dev/null
+++ b/arch/riscv/kernel/crash_core.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/crash_core.h>
+#include <linux/pagemap.h>
+
+void arch_crash_save_vmcoreinfo(void)
+{
+ VMCOREINFO_NUMBER(VA_BITS);
+ VMCOREINFO_NUMBER(phys_ram_base);
+
+ vmcoreinfo_append_str("NUMBER(PAGE_OFFSET)=0x%lx\n", PAGE_OFFSET);
+ vmcoreinfo_append_str("NUMBER(VMALLOC_START)=0x%lx\n", VMALLOC_START);
+ vmcoreinfo_append_str("NUMBER(VMALLOC_END)=0x%lx\n", VMALLOC_END);
+ vmcoreinfo_append_str("NUMBER(VMEMMAP_START)=0x%lx\n", VMEMMAP_START);
+ vmcoreinfo_append_str("NUMBER(VMEMMAP_END)=0x%lx\n", VMEMMAP_END);
+#ifdef CONFIG_64BIT
+ vmcoreinfo_append_str("NUMBER(MODULES_VADDR)=0x%lx\n", MODULES_VADDR);
+ vmcoreinfo_append_str("NUMBER(MODULES_END)=0x%lx\n", MODULES_END);
+#endif
+
+ if (IS_ENABLED(CONFIG_64BIT)) {
+#ifdef CONFIG_KASAN
+ vmcoreinfo_append_str("NUMBER(KASAN_SHADOW_START)=0x%lx\n", KASAN_SHADOW_START);
+ vmcoreinfo_append_str("NUMBER(KASAN_SHADOW_END)=0x%lx\n", KASAN_SHADOW_END);
+#endif
+ vmcoreinfo_append_str("NUMBER(KERNEL_LINK_ADDR)=0x%lx\n", KERNEL_LINK_ADDR);
+ vmcoreinfo_append_str("NUMBER(ADDRESS_SPACE_END)=0x%lx\n", ADDRESS_SPACE_END);
Seems this is the firsr ARCH where kasan and kernel link/bpf space are
added to dump and analyze. Just curious, have you got code change to
make use of them to do dumping and analyze?
KASAN_SHADOW_START is not used, KERNEL_LINK_ADDR is used in the crash patch set:
https://patchwork.kernel.org/project/linux-riscv/cover/20220813031753.3097720-1-xianting.tian@xxxxxxxxxxxxxxxxx/
Oh, I would say please no. Sometime we got tons of objection when adding an
necessary one, we definitely should not add one for possible future
use.
For this kind of newly added one, we need get ack from
makedumpfile/crash utility maintainer so that we know they are necessary
to have. At least they don't oppose.
Hi Kazu, Li Jiang
Could you help comment whether we need KASAN_SHADOW_START and KERNEL_LINK_ADDR area export for vmcore from crash point of view？
In my crash patch set, I don't use KASAN_SHADOW_START,
And only get the value of KERNEL_LINK_ADDR, not realy use it.
https://patchwork.kernel.org/project/linux-riscv/cover/20220813031753.3097720-1-xianting.tian@xxxxxxxxxxxxxxxxx/
In your crash patch set, KERNEL_LINK_ADDR is used in VTOP() and looks
necessary to me.
The others (KASAN_SHADOW_START, KASAN_SHADOW_END and ADDRESS_SPACE_END)
are not currently used. It may be better to add them when they are
really used.
I am very sorry, I missed it , KERNEL_LINK_ADDR is used indeed.
KASAN_SHADOW_START is not used, so I don't need to send crash patch set
again. only need to remove KASAN_SHADOW_END in kernel patch set.
Thanks,
Kazu
If we need to remove the two areas, I will resend the crash patch set and kernel patch set.
thanks
I add it in case of using in furture.
Thanks
Baoquan