Re: [Crash-utility] [PATCH V4 1/2] RISC-V: Add arch_crash_save_vmcoreinfo support

On Wed, Oct 26, 2022 at 08:05:41PM +0800, Baoquan He wrote: > Hi Xianting, > > On 10/26/22 at 05:44pm, Xianting Tian wrote: >> 在 2022/10/26 下午5:25, Conor Dooley 写道: >>> On Wed, Oct 26, 2022 at 05:08:11PM +0800, Xianting Tian wrote: >>>> Hi Palmer, Conor >>>> >>>> Is this version OK for you? >>> The weird ifdef/IS_ENABLED thing was the only comment I had. It's a bit >>> odd & I notice Baoquan brought it up too. I didn't (and won't) give you >>> a reviewed by on these patches because I don't understand the area well >>> enough. The general nitpickery seems to be sorted though. >> I checked the KERNEL_LINK_ADDR definition of riscv,  it is valid for >> CONFIG_64BIT and !CONFIG_64BIT. > This series looks good to me. My only minor concern is if we can make > the arch_crash_save_vmcoreinfo() as below. I don't understand why we > have to have the CONFIG_64BIT ifdeffery and the IS_ENABLED(CONFIG_64BIT) > between two adjacent code blocks. Not sure if we are saying the same > thing. I think we can just go and drop the IS_ENABLED(). From looking at it last time, one bit is compileable (but not usable) for !64BIT and the other isn't hence the IS_ENABLED(). I think it would make sense to drop the IS_ENABLED() - I don't think we're too likely to hit some compile testing edge cases that IS_ENABLED() would help with & only having one makes the code look a lot less odd and a lot more intentional.

> +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); > + vmcoreinfo_append_str("NUMBER(KERNEL_LINK_ADDR)=0x%lx\n", KERNEL_LINK_ADDR); > +#endif > +} > >> Maybe we can remove IS_ENABLED(CONFIG_64BIT) >> >> arch/riscv/include/asm/pgtable.h >> #define ADDRESS_SPACE_END       (UL(-1)) >> #ifdef CONFIG_64BIT >> /* Leave 2GB for kernel and BPF at the end of the address space */ >> #define KERNEL_LINK_ADDR        (ADDRESS_SPACE_END - SZ_2G + 1) >> #else >> #define KERNEL_LINK_ADDR        PAGE_OFFSET >> #endif >> >> arch/riscv/include/asm/page.h >> #ifdef CONFIG_64BIT >> #ifdef CONFIG_MMU >> #define PAGE_OFFSET             kernel_map.page_offset >> #else >> #define PAGE_OFFSET             _AC(CONFIG_PAGE_OFFSET, UL) >> #endif >> /* >>  * By default, CONFIG_PAGE_OFFSET value corresponds to SV48 address space so >>  * define the PAGE_OFFSET value for SV39. >>  */ >> #define PAGE_OFFSET_L4          _AC(0xffffaf8000000000, UL) >> #define PAGE_OFFSET_L3          _AC(0xffffffd800000000, UL) >> #else >> #define PAGE_OFFSET             _AC(CONFIG_PAGE_OFFSET, UL) >> #endif /* CONFIG_64BIT */ >> >>> Thanks, >>> Conor. >>> >>>> 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(a)linux.alibaba.com&gt; >>>>>>>>> --- >>>>>>>>>    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. >>>>>