[Crash-utility] Re: [PATCH v3 2/2] arm64: Add vmemmap support

If the kernel exports the vmmemap then we can use that symbol in crash to optimize access. vmmemap is just an array of page structs after all. This patch tries to: 1.) Get the "vmemmap" from the vmcore file. If we can use the "vmemmap", we implement the arm64_vmemmap_is_page_ptr and set it to machdep->is_page_ptr. 2.) We implement the fast page_to_pfn code in arm64_vmemmap_is_page_ptr. 3.) Dump "vmemmap" in "help -v". Test result: Test the patch: "[PATCH v3] add "files -n" command for an inode" https://lists.crash-utility.osci.io/archives/list/ devel(a)lists.crash-utility.osci.io/thread/CRLOQP534YKEQPTCXIWVDYK4NA7BOSUK/ Without the this patch: #files -n xxx (xxx is the inode of vmlinux which is 441M) This costed about 162 seconds. With the this patch: #files -n xxx (xxx is the inode of vmlinux which is 441M) This costed less then 1 second.

Signed-off-by: Huang Shijie <shijie(a)os.amperecomputing.com&gt; --- v2 --> v3: Use arm64_get_vmcoreinfo() to parse the "vmemmap" Dump it in "help -v" --- arm64.c | 25 +++++++++++++++++++++++++ defs.h | 1 + memory.c | 1 + 3 files changed, 27 insertions(+) diff --git a/arm64.c b/arm64.c index 57965c6..fd6e9f7 100644 --- a/arm64.c +++ b/arm64.c @@ -117,6 +117,28 @@ static void arm64_calc_kernel_start(void) ms->kimage_end = (sp ? sp->value : 0); } +static int +arm64_vmemmap_is_page_ptr(ulong addr, physaddr_t *phys) +{ + ulong size = SIZE(page); + ulong pfn, nr; + + + if (IS_SPARSEMEM() && (machdep->flags & VMEMMAP) && + (addr >= VMEMMAP_VADDR && addr <= VMEMMAP_END) && + !((addr - VMEMMAP_VADDR) % size)) { + + pfn = (addr - vt->vmemmap) / size; + nr = pfn_to_section_nr(pfn); + if (valid_section_nr(nr)) { + if (phys) + *phys = PTOB(pfn); + return TRUE; + } + } + return FALSE; +} + /* * Do all necessary machine-specific setup here. This is called several times * during initialization. @@ -382,6 +404,9 @@ arm64_init(int when) machdep->stacksize = ARM64_STACK_SIZE; machdep->flags |= VMEMMAP; + /* If vmemmap exists, it means kernel enabled CONFIG_SPARSEMEM_VMEMMAP */ + if (arm64_get_vmcoreinfo(&vt->vmemmap, "SYMBOL(vmemmap)", NUM_HEX)) + machdep->is_page_ptr = arm64_vmemmap_is_page_ptr; machdep->uvtop = arm64_uvtop; machdep->is_uvaddr = arm64_is_uvaddr; diff --git a/defs.h b/defs.h index 0558d13..bb775fd 100644 --- a/defs.h +++ b/defs.h @@ -2634,6 +2634,7 @@ struct vm_table { /* kernel VM-related data */ ulong max_mem_section_nr; ulong zero_paddr; ulong huge_zero_paddr; + ulong vmemmap;