Currently get_mem_section() validates if SYMBOL(mem_section) is the address
of the mem_section array first. But there was a report that the first
validation wrongly returned TRUE with -x vmlinux and SPARSEMEM_EXTREME
(4.15+) on s390x. This leads to crash failing statup with the following
seek error:
crash: seek error: kernel virtual address: 67fffc2800 type: "memory section root table"
Skip the first validation when satisfying the conditions.
Reported-by: Dave Wysochanski <dwysocha@xxxxxxxxxx>
Signed-off-by: Kazuhito Hagio <k-hagio-ab@xxxxxxx>
---
makedumpfile.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/makedumpfile.c b/makedumpfile.c
index a2f45c84cee3..65d1c7c2f02c 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -3698,6 +3698,22 @@ validate_mem_section(unsigned long *mem_sec,
return ret;
}
+/*
+ * SYMBOL(mem_section) varies with the combination of memory model and
+ * its source:
+ *
+ * SPARSEMEM
+ * vmcoreinfo: address of mem_section root array
+ * -x vmlinux: address of mem_section root array
+ *
+ * SPARSEMEM_EXTREME v1
+ * vmcoreinfo: address of mem_section root array
+ * -x vmlinux: address of mem_section root array
+ *
+ * SPARSEMEM_EXTREME v2 (with 83e3c48729d9 and a0b1280368d1) 4.15+
+ * vmcoreinfo: address of mem_section root array
+ * -x vmlinux: address of pointer to mem_section root array
+ */
static int
get_mem_section(unsigned int mem_section_size, unsigned long *mem_maps,
unsigned int num_section)
@@ -3710,12 +3726,27 @@ get_mem_section(unsigned int mem_section_size, unsigned long *mem_maps,
strerror(errno));
return FALSE;
}
+
+ /*
+ * There was a report that the first validation wrongly returned TRUE
+ * with -x vmlinux and SPARSEMEM_EXTREME v2 on s390x, so skip it.
+ * Howerver, leave the fallback validation as it is for the -i option.
+ */
+ if (is_sparsemem_extreme() && info->name_vmlinux) {
+ unsigned long flag = 0;
+ if (get_symbol_type_name("mem_section", DWARF_INFO_GET_SYMBOL_TYPE,
+ NULL, &flag)
+ && !(flag & TYPE_ARRAY))
+ goto skip_1st_validation;
+ }
+
ret = validate_mem_section(mem_sec, SYMBOL(mem_section),
mem_section_size, mem_maps, num_section);
if (!ret && is_sparsemem_extreme()) {
unsigned long mem_section_ptr;
+skip_1st_validation:
if (!readmem(VADDR, SYMBOL(mem_section), &mem_section_ptr,
sizeof(mem_section_ptr)))
goto out;
--
2.27.0
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