Re: [PATCH V3 1/2] RISC-V: Add arch_crash_save_vmcoreinfo support

[Xianting Tian]

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/

I add it in case of using in furture.

> Thanks
> Baoquan