[Crash-utility] [PATCH] gdb: fix the "p" command incorrectly print the value of a global variable
Some objects format may potentially support copy relocations, but
currently the maybe_copied is always initialized to 0 in the symbol().
And the type is 'mst_file_bss', not always the 'mst_bss' or
'mst_data'
in the lookup_minimal_symbol_linkage(). For example:
(gdb) p *msymbol
$42 = {<general_symbol_info> = {m_name = 0x349812f "test_no_static", value
= {ivalue = 8, block = 0x8,
bytes = 0x8 <error: Cannot access memory at address 0x8>, address = 8,
common_block = 0x8, chain = 0x8}, language_specific = {
obstack = 0x0, demangled_name = 0x0}, m_language = language_auto, ada_mangled = 0,
section = 20}, size = 4,
filename = 0x6db3440 "test_sanity.c", type = mst_file_bss, created_by_gdb = 0,
target_flag_1 = 0, target_flag_2 = 0, has_size = 1,
maybe_copied = 0, name_set = 1, hash_next = 0x0, demangled_hash_next = 0x0}
This causes a problem that the 'p' command can not work well as
expected, and always gets an error:
crash> mod -s test_sanity /home/test_sanity.ko
MODULE NAME BASE SIZE OBJECT FILE
ffffffffc1084040 test_sanity ffffffffc1082000 16384
/home/test_sanity.ko
crash> p test_no_static
p: gdb request failed: p test_no_static
crash>
With the patch:
crash> mod -s test_sanity /home/test_sanity.ko
MODULE NAME BASE SIZE OBJECT FILE
ffffffffc1084040 test_sanity ffffffffc1082000 16384
/home/test_sanity.ko
crash> p test_no_static
test_no_static = $1 = 5
crash>
Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com>
---
Here is the test case:
#include <linux/kernel.h>
#include <linux/module.h>
int test_no = 0;
static int test_no_static = 0;
static int test_init(void)
{
test_no += 5;
test_no_static += 5;
printk(KERN_INFO "%d static=%d\n", test_no, test_no_static);
return 0;
}
static void test_exit(void)
{
test_no += 7;
test_no_static += 7;
printk(KERN_INFO "%d static=%d\n", test_no, test_no_static);
}
module_init(test_init);
module_exit(test_exit);
MODULE_LICENSE("GPL");
gdb-10.2.patch | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)
diff --git a/gdb-10.2.patch b/gdb-10.2.patch
index a7018a249118..35388ba03e25 100644
--- a/gdb-10.2.patch
+++ b/gdb-10.2.patch
@@ -16057,3 +16057,27 @@ exit 0
m10200-dis.c
m10200-opc.c
m10300-dis.c
+--- gdb-10.2/gdb/minsyms.c.orig
++++ gdb-10.2/gdb/minsyms.c
+@@ -535,7 +535,9 @@ lookup_minimal_symbol_linkage (const char *name, struct objfile
*objf)
+ {
+ if (strcmp (msymbol->linkage_name (), name) == 0
+ && (MSYMBOL_TYPE (msymbol) == mst_data
+- || MSYMBOL_TYPE (msymbol) == mst_bss))
++ || MSYMBOL_TYPE (msymbol) == mst_bss
++ || MSYMBOL_TYPE (msymbol) == mst_file_bss
++ || MSYMBOL_TYPE (msymbol) == mst_file_data))
+ return {msymbol, objfile};
+ }
+ }
+--- gdb-10.2/gdb/symtab.h.orig
++++ gdb-10.2/gdb/symtab.h
+@@ -1110,7 +1110,7 @@ struct symbol : public general_symbol_info, public
allocate_on_obstack
+ is_objfile_owned (1),
+ is_argument (0),
+ is_inlined (0),
+- maybe_copied (0),
++ maybe_copied (1),/* The objfile potentially supports copy relocations. */
+ subclass (SYMBOL_NONE)
+ {
+ /* We can't use an initializer list for members of a base class, and
--
2.41.0