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

[Xianting Tian]

Hi Conor,

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:
>> 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 default pagetable levels, it sets sv57 on defaultly
>> in latest kernel and do fallback to try to set sv48 on boot time if sv57
>> is not supported in current hardware.
> nit: This would read better as "it sets sv57 by default and falls back
> to setting sv48 at boot time if sv57 is not supported by the hardware".
will fix in V3
>
>> For ram base, the default value is 0x80200000 for qemu riscv64 env, 0x200000
>> for riscv64 SoC platform(eg, SoC platform of RISC-V XuanTie 910 CPU).
> The second part of this sentence I'm not really sure that that is true,
> I think you should reword it to something like "...for qemu riscv64 and,
> for example, is 0x200000 on the XuanTie 910 CPU." and avoid applying
> that number blanketly for other SoCs.
will fix in V3
>>   * 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 at 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.

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
>>
>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listman.redhat.com/archives/crash-utility/attachments/20221018/72b92845/attachment-0001.htm>