[PATCH v2 1/1] Calculate offset to field 'init_uts_ns.name'

[Alexander Egorenkov]

The offset has changed in linux-next (v5.9.0) from 4 to 0 because
there is no more 'kref' member variable at the beginning of 'init_uts_ns'.
The change was introduced with commit 9a56493f6942c0e2df1579986128721da96e00d8.
To handle both cases correctly, calculate the offset at run time instead.

Signed-off-by: Alexander Egorenkov <egorenar at linux.ibm.com>
---
 makedumpfile.c | 8 ++++++--
 makedumpfile.h | 4 ++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/makedumpfile.c b/makedumpfile.c
index 4c4251e..2d62db8 100644
--- a/makedumpfile.c
+++ b/makedumpfile.c
@@ -1159,7 +1159,7 @@ check_release(void)
 	if (SYMBOL(system_utsname) != NOT_FOUND_SYMBOL) {
 		utsname = SYMBOL(system_utsname);
 	} else if (SYMBOL(init_uts_ns) != NOT_FOUND_SYMBOL) {
-		utsname = SYMBOL(init_uts_ns) + sizeof(int);
+		utsname = SYMBOL(init_uts_ns) + OFFSET(init_uts_ns.name);
 	} else {
 		ERRMSG("Can't get the symbol of system_utsname.\n");
 		return FALSE;
@@ -2077,7 +2077,7 @@ get_str_osrelease_from_vmlinux(void)
 	if (SYMBOL(system_utsname) != NOT_FOUND_SYMBOL) {
 		utsname = SYMBOL(system_utsname);
 	} else if (SYMBOL(init_uts_ns) != NOT_FOUND_SYMBOL) {
-		utsname = SYMBOL(init_uts_ns) + sizeof(int);
+		utsname = SYMBOL(init_uts_ns) + OFFSET(init_uts_ns.name);
 	} else {
 		ERRMSG("Can't get the symbol of system_utsname.\n");
 		return FALSE;
@@ -2285,6 +2285,8 @@ write_vmcoreinfo_data(void)
 	WRITE_MEMBER_OFFSET("mmu_psize_def.shift", mmu_psize_def.shift);
 	WRITE_MEMBER_OFFSET("cpu_spec.mmu_features", cpu_spec.mmu_features);
 
+	WRITE_MEMBER_OFFSET("init_uts_ns.name", init_uts_ns.name);
+
 	if (SYMBOL(node_data) != NOT_FOUND_SYMBOL)
 		WRITE_ARRAY_LENGTH("node_data", node_data);
 	if (SYMBOL(pgdat_list) != NOT_FOUND_SYMBOL)
@@ -2697,6 +2699,8 @@ read_vmcoreinfo(void)
 		READ_MEMBER_OFFSET("log.text_len", printk_log.text_len);
 	}
 
+	READ_MEMBER_OFFSET("init_uts_ns.name", init_uts_ns.name);
+
 	READ_ARRAY_LENGTH("node_data", node_data);
 	READ_ARRAY_LENGTH("pgdat_list", pgdat_list);
 	READ_ARRAY_LENGTH("mem_section", mem_section);
diff --git a/makedumpfile.h b/makedumpfile.h
index 03fb4ce..7d8c54d 100644
--- a/makedumpfile.h
+++ b/makedumpfile.h
@@ -1880,6 +1880,10 @@ struct offset_table {
 	struct cpu_spec_s {
 		long	mmu_features;
 	} cpu_spec;
+
+	struct init_uts_ns_s {
+		long	name;
+	} init_uts_ns;
 };
 
 /*
-- 
2.26.2