[Crash-utility] [PATCH 2/2] 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 get the "vmemmap" from the vmcore file.
If we can use the "vmemmap", use the vmemmap_is_page_ptr to replace
the generic_is_page_ptr().
If we have vmemmap then we can implement fast page_to_pfn code in
vmemmap_is_page_ptr
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>
---
defs.h | 3 +++
memory.c | 35 +++++++++++++++++++++++++++++++++++
2 files changed, 38 insertions(+)
diff --git a/defs.h b/defs.h
index eec7b3e..25bb455 100644
--- a/defs.h
+++ b/defs.h
@@ -2615,6 +2615,7 @@ struct vm_table { /* kernel VM-related data */
ulong vma_cache_fills;
void *mem_sec;
char *mem_section;
+ ulong vmemmap;
int ZONE_HIGHMEM;
ulong *node_online_map;
int node_online_map_len;
@@ -2665,10 +2666,12 @@ struct vm_table { /* kernel VM-related data */
#define SLAB_OVERLOAD_PAGE (0x8000000)
#define SLAB_CPU_CACHE (0x10000000)
#define SLAB_ROOT_CACHES (0x20000000)
+#define SPARSEMEM_VMEMMAP (0x40000000)
#define IS_FLATMEM() (vt->flags & FLATMEM)
#define IS_DISCONTIGMEM() (vt->flags & DISCONTIGMEM)
#define IS_SPARSEMEM() (vt->flags & SPARSEMEM)
+#define IS_SPARSEMEM_VMEMMAP() (vt->flags & SPARSEMEM_VMEMMAP)
#define IS_SPARSEMEM_EX() (vt->flags & SPARSEMEM_EX)
#define COMMON_VADDR_SPACE() (vt->flags & COMMON_VADDR)
diff --git a/memory.c b/memory.c
index ed1a4fb..668567f 100644
--- a/memory.c
+++ b/memory.c
@@ -17462,6 +17462,39 @@ sparse_decode_mem_map(ulong coded_mem_map, ulong section_nr)
(section_nr_to_pfn(section_nr) * SIZE(page));
}
+static int
+vmemmap_is_page_ptr(ulong addr, physaddr_t *phys)
+{
+ ulong pfn;
+
+ if (IS_SPARSEMEM_VMEMMAP() &&
+ (VMEMMAP_VADDR <= addr && addr < VMEMMAP_END)) {
+ ulong size = SIZE(page);
+
+ /* Not aligned with the page structure */
+ if ((addr - vt->vmemmap) % size)
+ return FALSE;
+
+ pfn = (addr - vt->vmemmap) / size;
+ if (phys)
+ *phys = PTOB(pfn);
+ return TRUE;
+ }
+ return FALSE;
+}
+
+static bool
+check_sparsemem_vmemmap(void)
+{
+ if (!get_value_vmcore("SYMBOL(vmemmap)", &vt->vmemmap))
+ return FALSE;
+
+ vt->flags |= SPARSEMEM_VMEMMAP;
+ if (machdep->is_page_ptr == generic_is_page_ptr)
+ machdep->is_page_ptr = vmemmap_is_page_ptr;
+ return TRUE;
+}
+
void
sparse_mem_init(void)
{
@@ -17472,6 +17505,8 @@ sparse_mem_init(void)
if (!IS_SPARSEMEM())
return;
+ check_sparsemem_vmemmap();
+
MEMBER_OFFSET_INIT(mem_section_section_mem_map, "mem_section",
"section_mem_map");
--
2.40.1