From 4141373d9de3fea29f5d2b58f60e44bc132726c0 Mon Sep 17 00:00:00 2001
From: Dave Anderson <anderson@redhat.com>
Date: Tue, 6 Mar 2018 11:26:05 -0500
Subject: [PATCH] Implemented the x86_64 machdep->is_page_ptr() plugin
 function.  If the kernel is configured with CONFIG_SPARSEMEM_VMEMMAP, the
 plugin function optimizes the mem_section search, reducing the computation
 effort and time consumed by commands that repeatedly call the is_page_ptr()
 function on large-memory systems. (k-hagio@ab.jp.nec.com)

---
 defs.h   |  1 +
 x86_64.c | 23 +++++++++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/defs.h b/defs.h
index 9663bd89..7998ebfd 100644
--- a/defs.h
+++ b/defs.h
@@ -5133,6 +5133,7 @@ int vaddr_type(ulong, struct task_context *);
 char *format_stack_entry(struct bt_info *bt, char *, ulong, ulong);
 int in_user_stack(ulong, ulong);
 int dump_inode_page(ulong);
+ulong valid_section_nr(ulong);
 
 
 /*
diff --git a/x86_64.c b/x86_64.c
index 74495719..0d5e150d 100644
--- a/x86_64.c
+++ b/x86_64.c
@@ -77,6 +77,7 @@ static void x86_64_calc_phys_base(void);
 static int x86_64_is_module_addr(ulong);
 static int x86_64_is_kvaddr(ulong);
 static int x86_64_is_uvaddr(ulong, struct task_context *);
+static int x86_64_is_page_ptr(ulong, physaddr_t *);
 static ulong *x86_64_kpgd_offset(ulong, int, int);
 static ulong x86_64_upgd_offset(struct task_context *, ulong, int, int);
 static ulong x86_64_upgd_offset_legacy(struct task_context *, ulong, int, int);
@@ -156,6 +157,7 @@ x86_64_init(int when)
 	{
 	case SETUP_ENV:
 		machdep->process_elf_notes = x86_process_elf_notes;
+		machdep->is_page_ptr = x86_64_is_page_ptr;
 		break;
 	case PRE_SYMTAB:
 		machdep->verify_symbol = x86_64_verify_symbol;
@@ -802,6 +804,7 @@ x86_64_dump_machdep_table(ulong arg)
 	fprintf(fp, "       get_smp_cpus: x86_64_get_smp_cpus()\n");
         fprintf(fp, "          is_kvaddr: x86_64_is_kvaddr()\n");
         fprintf(fp, "          is_uvaddr: x86_64_is_uvaddr()\n");
+        fprintf(fp, "        is_page_ptr: x86_64_is_page_ptr()\n");
         fprintf(fp, "       verify_paddr: x86_64_verify_paddr()\n");
         fprintf(fp, "  get_kvaddr_ranges: x86_64_get_kvaddr_ranges()\n");
         fprintf(fp, "    init_kernel_pgd: x86_64_init_kernel_pgd()\n");
@@ -1594,6 +1597,26 @@ x86_64_is_uvaddr(ulong addr, struct task_context *tc)
         return (addr < USERSPACE_TOP);
 }
 
+static int
+x86_64_is_page_ptr(ulong addr, physaddr_t *phys)
+{
+	ulong pfn, nr;
+
+	if (IS_SPARSEMEM() && (machdep->flags & VMEMMAP) &&
+	    (addr >= VMEMMAP_VADDR && addr <= VMEMMAP_END) &&
+	    !((addr - VMEMMAP_VADDR) % SIZE(page))) {
+
+		pfn = (addr - VMEMMAP_VADDR) / SIZE(page);
+		nr = pfn_to_section_nr(pfn);
+		if (valid_section_nr(nr)) {
+			if (phys)
+				*phys = PTOB(pfn);
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+
 /*
  * Find the kernel pgd entry..
  * pgd = pgd_offset_k(addr);