Re: [PATCH V2 1/2] RISC-V: Add arch_crash_save_vmcoreinfo support

[Xianting Tian <xianting.tian@linux.alibaba.com>]

在 2022/10/18 下午3:19, Conor.Dooley@microchip.com 写道:
> On 18/10/2022 03:28, Xianting Tian wrote:
>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
>>
>> 在 2022/10/18 上午3:54, Conor Dooley 写道:
>>
>>> On Fri, Oct 14, 2022 at 09:41:38PM +0800, Xianting Tian wrote:
>>>>    * 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@linux.alibaba.com>
>>>> ---
>>>>    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)) {
>>> You've already got a #ifdef CONFIG_64BIT above, is there a reason why
>>> you'd use the IS_ENABLED here rather than merge this with the above
>>> section? I'm a big fan of IS_ENABLED but I'm not sure what it adds here,
>>> maybe you can show me the light :)
>> The IS_ENABLED() check prevents the line from getting executed, but
>> unlike an #ifdef it relies on it to be parsable.
> Hey Xianting,
> Firstly, neither this nor the other version of this message made it to
> the mailing list - and since I usually use lei to get my mails that is
> a bit of a problem :(

Sorry, I don't know why,  I just reply via Thunderbird.

But git send-mail is right, I will send V3 soon.

>
> Yeah, I know that that is what IS_ENABLED() does, it's just in this
> situation it does not look very intentional & more like disjoint bits
> of copy-paste. It's fine though, leave it as it is.
OK, thanks
>
> Thanks,
> Conor.
>
>> I wrote this arch_crash_save_vmcoreinfo() func with reference to this: static void __init print_vm_layout(void) // arch/riscv/mm/init.c
>> {
>>           pr_notice("Virtual kernel memory layout:\n");
>>           print_ml("fixmap", (unsigned long)FIXADDR_START,
>>                   (unsigned long)FIXADDR_TOP);
>>           print_ml("pci io", (unsigned long)PCI_IO_START,
>>                   (unsigned long)PCI_IO_END);
>>           print_ml("vmemmap", (unsigned long)VMEMMAP_START,
>>                   (unsigned long)VMEMMAP_END);
>>           print_ml("vmalloc", (unsigned long)VMALLOC_START,
>>                   (unsigned long)VMALLOC_END);
>> #ifdef CONFIG_64BIT
>>           print_ml("modules", (unsigned long)MODULES_VADDR,
>>                   (unsigned long)MODULES_END);
>> #endif
>>           print_ml("lowmem", (unsigned long)PAGE_OFFSET,
>>                   (unsigned long)high_memory);
>>           if (IS_ENABLED(CONFIG_64BIT)) {
>> #ifdef CONFIG_KASAN
>>                   print_ml("kasan", KASAN_SHADOW_START, KASAN_SHADOW_END);
>> #endif
>>
>>                   print_ml("kernel", (unsigned long)KERNEL_LINK_ADDR,
>>                            (unsigned long)ADDRESS_SPACE_END);
>>           }
>> }
>>
>>> Thanks,
>>> Conor.
>>>
>>>
>>>> +#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);
>>>> +	}
>>>> +}
>>>> -- 
>>>> 2.17.1
>>>>
>>>>