[Crash-utility] [PATCH] arm64: fix the wrong vmemmap_end

[Huang Shijie]

Before the kernel v5.7, the VMEMMAP_END does not exit.

In the patch
   "e397e1b arm64: update the modules/vmalloc/vmemmap ranges"
it sets -1(0xffffffffffffffffUL) for vmemmap_end for
the kernel versions before v5.7.

But from the arch/arm64/mm/dump.c (before kernel v5.7):
    ......................................
	{ VMEMMAP_START + VMEMMAP_SIZE,	"vmemmap end" }
    ......................................
we can know that the vmemmap_end should always be:
	vmemmap_end = vmemmap_vaddr + vmemmap_size;

This patch fixes this issue.

Signed-off-by: Huang Shijie <shijie at os.amperecomputing.com>
---
 arm64.c | 26 +++++++++++---------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/arm64.c b/arm64.c
index d81c2b9..f75599e 100644
--- a/arm64.c
+++ b/arm64.c
@@ -285,11 +285,7 @@ arm64_init(int when)
 				ms->vmalloc_start_addr	= r->vmalloc_start_addr;
 				ms->vmalloc_end		= r->vmalloc_end - 1;
 				ms->vmemmap_vaddr	= r->vmemmap_vaddr;
-				if (THIS_KERNEL_VERSION >= LINUX(5, 7, 0))
-					ms->vmemmap_end		= r->vmemmap_end - 1;
-				else
-					ms->vmemmap_end		= -1;
-
+				ms->vmemmap_end		= r->vmemmap_end - 1;
 			} else if (ms->VA_BITS_ACTUAL) {
 				ms->modules_vaddr = (st->_stext_vmlinux & TEXT_OFFSET_MASK) - ARM64_MODULES_VSIZE;
 				ms->modules_end = ms->modules_vaddr + ARM64_MODULES_VSIZE -1;
@@ -739,15 +735,15 @@ static struct kernel_range *arm64_get_range_v5_4(struct machine_specific *ms)
 	vmemmap_size = (_PAGE_END(v) - PAGE_OFFSET) >> vmem_shift;
 
 	r->vmemmap_vaddr = (-vmemmap_size - SZ_2M);
-	if (THIS_KERNEL_VERSION >= LINUX(5, 7, 0)) {
-		/*
-		 *  In the v5.7, the patch: "bbd6ec605c arm64/mm: Enable memory hot remove"
-		 *      adds the VMEMMAP_END.
-		 */
-		r->vmemmap_end = r->vmemmap_vaddr + vmemmap_size;
-	} else {
-		r->vmemmap_end = 0xffffffffffffffffUL;
-	}
+	/*
+	 *  In the v5.7, the patch: "bbd6ec605c arm64/mm: Enable memory hot remove"
+	 *      adds the VMEMMAP_END.
+	 *
+	 *  But before the VMEMMAP_END was added to kernel, we can also see
+	 *  the following in arch/arm64/mm/dump.c:
+	 *   { VMEMMAP_START + VMEMMAP_SIZE,	"vmemmap end" },
+	 */
+	r->vmemmap_end = r->vmemmap_vaddr + vmemmap_size;
 
 	/* Get the VMALLOC_START ~ VMALLOC_END */
 	PUD_SIZE = arm64_get_pud_size();
@@ -795,7 +791,7 @@ static struct kernel_range *arm64_get_range_v5_0(struct machine_specific *ms)
 	vmemmap_size = (1UL << (v - machdep->pageshift - 1 + arm64_get_struct_page_max_shift(ms)));
 
 	r->vmemmap_vaddr = page_offset - vmemmap_size;
-	r->vmemmap_end = 0xffffffffffffffffUL;  /* this kernel does not have VMEMMAP_END */
+	r->vmemmap_end = r->vmemmap_vaddr + vmemmap_size; /* See the arch/arm64/mm/dump.c */
 
 	/* Get the VMALLOC_START ~ VMALLOC_END */
 	PUD_SIZE = arm64_get_pud_size();
-- 
2.30.2