Date: Sun, 28 Jul 2024 14:21:58 -0000
From: qiwu.chen@transsion.com
Subject: [Crash-utility] [PATCH] arm64: fix the determination of
        vmemmap and struct_page_size
To: devel@lists.crash-utility.osci.io
Message-ID: <20240728142158.17290.96096@lists.crash-utility.osci.io>
Content-Type: text/plain; charset="utf-8"

Currently, the vmemmap ptr addr is determined by the vmcoreinfo of "SYMBOL(vmemmap)", which leads to an invalid vmemmap addr showed by "help -m" for dump files without the vmcoreinfo. The value of vmemmap_end is simply set to -1 for available VA_BITS_ACTUAL case in arm64_calc_virtual_memory_ranges(), and the struct_page_size value is 0.
crash> help -m |grep vmem
         vmemmap_vaddr: fffffffeffe00000
           vmemmap_end: ffffffffffffffff
               vmemmap: 0000000000000000
crash> help -m |grep struct_page_size
      struct_page_size: 0

Introduce arm64_get_vmemmap_page_ptr() to fix the determination of vmemmap ptr addr, and fix the determination of vmemmap_end and struct_page_size in arm64_calc_virtual_memory_ranges().
crash> help -m |grep vmem
         vmemmap_vaddr: fffffffeffe00000
           vmemmap_end: ffffffffffe00000
               vmemmap: fffffffefee00000
crash> help -m |grep struct_page_size
      struct_page_size: 64

Signed-off-by: qiwu.chen <qiwu.chen@qq.com>
---
 arm64.c | 29 +++++++++++++++++++++++------
 1 file changed, 23 insertions(+), 6 deletions(-)

diff --git a/arm64.c b/arm64.c
index 78e6609..ef495ec 100644
--- a/arm64.c
+++ b/arm64.c
@@ -159,7 +159,6 @@ 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)) {
@@ -175,6 +174,25 @@ arm64_vmemmap_is_page_ptr(ulong addr, physaddr_t *phys)
        return FALSE;
 }

+static void arm64_get_vmemmap_page_ptr(void)
+{
+       struct machine_specific *ms = machdep->machspec;
+
+       /* If vmemmap exists, it means kernel enabled CONFIG_SPARSEMEM_VMEMMAP */
+       if (arm64_get_vmcoreinfo(&ms->vmemmap, "SYMBOL(vmemmap)", NUM_HEX))
+               goto out;
+
+       /* The global symbol of vmemmap is removed since kernel commit 7bc1a0f9e1765 */
+       if (!kernel_symbol_exists("vmemmap"))
+               ms->vmemmap = ms->vmemmap_vaddr - ((ms->phys_offset >> machdep->pageshift) * ms->struct_page_size);
+       else
+               ms->vmemmap = symbol_value("vmemmap");
+
+out:
+       if (ms->vmemmap)
+               machdep->is_page_ptr = arm64_vmemmap_is_page_ptr;
+}
+
 /*
  * Do all necessary machine-specific setup here. This is called several times
  * during initialization.
@@ -443,10 +461,6 @@ 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(&ms->vmemmap, "SYMBOL(vmemmap)", NUM_HEX))
-                       machdep->is_page_ptr = arm64_vmemmap_is_page_ptr;
-
                machdep->uvtop = arm64_uvtop;
                machdep->is_uvaddr = arm64_is_uvaddr;
                machdep->eframe_search = arm64_eframe_search;
@@ -498,6 +512,7 @@ arm64_init(int when)
                if (!ms->struct_page_size)
                        arm64_calc_virtual_memory_ranges();

+               arm64_get_vmemmap_page_ptr();
                arm64_get_section_size_bits();

                if (!machdep->max_physmem_bits) {
@@ -4841,6 +4856,7 @@ arm64_calc_virtual_memory_ranges(void)
                return;

        STRUCT_SIZE_INIT(page, "page");
+       ms->struct_page_size = SIZE(page);

         switch (machdep->flags & (VM_L2_64K|VM_L3_64K|VM_L3_4K|VM_L4_4K))
         {
@@ -4868,7 +4884,8 @@ arm64_calc_virtual_memory_ranges(void)
                vmemmap_start = (-vmemmap_size - MEGABYTES(2));
                ms->vmalloc_end = vmalloc_end - 1;
                ms->vmemmap_vaddr = vmemmap_start;
-               ms->vmemmap_end = -1;
+               ms->vmemmap_end = vmemmap_start + vmemmap_size;
+
                return;
        }

--
2.25.1