linux-kernel - Re: [PATCH V4 1/2] RISC-V: Add arch_crash_save

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Date:   Wed, 26 Oct 2022 17:08:11 +0800
From:   Xianting Tian <xianting.tian@...ux.alibaba.com>
To:     Baoquan He <bhe@...hat.com>, Palmer Dabbelt <palmer@...belt.com>,
        Conor Dooley <Conor.Dooley@...rochip.com>
Cc:     paul.walmsley@...ive.com, aou@...s.berkeley.edu,
        anup@...infault.org, heiko@...ech.de, guoren@...nel.org,
        mick@....forth.gr, alexandre.ghiti@...onical.com,
        vgoyal@...hat.com, dyoung@...hat.com, corbet@....net,
        bagasdotme@...il.com, k-hagio-ab@....com, lijiang@...hat.com,
        kexec@...ts.infradead.org, linux-doc@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
        crash-utility@...hat.com, heinrich.schuchardt@...onical.com,
        hschauhan@...ltrace.org, yixun.lan@...il.com
Subject: Re: [PATCH V4 1/2] RISC-V: Add arch_crash_save_vmcoreinfo support

Hi Palmer, Conor

Is this version OK for you? Do you plan to apply this patch set? thanks

在 2022/10/20 下午12:40, Xianting Tian 写道:
>
> 在 2022/10/20 上午11:05, Baoquan He 写道:
>> On 10/20/22 at 10:17am, Xianting Tian wrote:
>>> 在 2022/10/20 上午10:08, Baoquan He 写道:
>>>> On 10/19/22 at 06:36pm, Xianting Tian wrote:
>>>>> Add arch_crash_save_vmcoreinfo(), which exports VM layout(MODULES, 
>>>>> VMALLOC,
>>>>> VMEMMAP ranges and KERNEL_LINK_ADDR), 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@...ux.alibaba.com>
>>>>> ---
>>>>>    arch/riscv/kernel/Makefile     |  1 +
>>>>>    arch/riscv/kernel/crash_core.c | 23 +++++++++++++++++++++++
>>>>>    2 files changed, 24 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..3e889d0ed7bd
>>>>> --- /dev/null
>>>>> +++ b/arch/riscv/kernel/crash_core.c
>>>>> @@ -0,0 +1,23 @@
>>>>> +// 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))
>>>>> + vmcoreinfo_append_str("NUMBER(KERNEL_LINK_ADDR)=0x%lx\n", 
>>>>> KERNEL_LINK_ADDR);
>>>> Wondering why you don't put KERNEL_LINK_ADDR exporting into the above
>>>> ifdeffery scope, with that you can save one line of 
>>>> "IS_ENABLED(CONFIG_64BIT)".
>>> I followed the rule in print_vm_layout() of arch/riscv/mm/init.c, 
>>> which used
>>> IS_ENABLED when print the value of KERNEL_LINK_ADDR.
>>>
>> I see. There's PAGE_OFFSET in the middle. Thanks.
>>
>>          print_ml("lowmem", (unsigned long)PAGE_OFFSET,
>>                  (unsigned long)high_memory)
>>
>> So now, do you think if it's necessary to have another
>> IS_ENABLED(CONFIG_64BIT) in the current arch_crash_save_vmcoreinfo()?
>
> For which MACRO?  I think current code for PAGE_OFFSET is OK.
>