[PATCH] module: set ksymtab/kcrctab* section addresses to 0x0

From: Rabin Vincent
Date: Mon Jan 26 2015 - 15:46:12 EST


These __ksymtab*/__kcrctab* sections currently have non-zero addresses.
Non-zero section addresses in a relocatable ELF confuse GDB and it ends
up not relocating all symbols when add-symbol-file is used on modules
which have exports. The kernel's module loader does not care about
these addresses, so let's just set them to zero.

Before:

$ readelf -S lib/notifier-error-inject.ko | grep 'Name\| __ksymtab_gpl'
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[ 8] __ksymtab_gpl PROGBITS 0000000c 0001b4 000010 00 A 0 0 4

(gdb) add-symbol-file lib/notifier-error-inject.ko 0x500000 -s .bss 0x700000
add symbol table from file "lib/notifier-error-inject.ko" at
.text_addr = 0x500000
.bss_addr = 0x700000
(gdb) p &notifier_err_inject_dir
$3 = (struct dentry **) 0x0

After:

$ readelf -S lib/notifier-error-inject.ko | grep 'Name\| __ksymtab_gpl'
[Nr] Name Type Addr Off Size ES Flg Lk Inf Al
[ 8] __ksymtab_gpl PROGBITS 00000000 0001b4 000010 00 A 0 0 4

(gdb) add-symbol-file lib/notifier-error-inject.ko 0x500000 -s .bss 0x700000
add symbol table from file "lib/notifier-error-inject.ko" at
.text_addr = 0x500000
.bss_addr = 0x700000
(gdb) p &notifier_err_inject_dir
$3 = (struct dentry **) 0x700000

Signed-off-by: Rabin Vincent <rabin.vincent@xxxxxxxx>
---
scripts/module-common.lds | 20 ++++++++++----------
1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/scripts/module-common.lds b/scripts/module-common.lds
index 0865b3e..bec15f9 100644
--- a/scripts/module-common.lds
+++ b/scripts/module-common.lds
@@ -6,14 +6,14 @@
SECTIONS {
/DISCARD/ : { *(.discard) }

- __ksymtab : { *(SORT(___ksymtab+*)) }
- __ksymtab_gpl : { *(SORT(___ksymtab_gpl+*)) }
- __ksymtab_unused : { *(SORT(___ksymtab_unused+*)) }
- __ksymtab_unused_gpl : { *(SORT(___ksymtab_unused_gpl+*)) }
- __ksymtab_gpl_future : { *(SORT(___ksymtab_gpl_future+*)) }
- __kcrctab : { *(SORT(___kcrctab+*)) }
- __kcrctab_gpl : { *(SORT(___kcrctab_gpl+*)) }
- __kcrctab_unused : { *(SORT(___kcrctab_unused+*)) }
- __kcrctab_unused_gpl : { *(SORT(___kcrctab_unused_gpl+*)) }
- __kcrctab_gpl_future : { *(SORT(___kcrctab_gpl_future+*)) }
+ __ksymtab 0 : { *(SORT(___ksymtab+*)) }
+ __ksymtab_gpl 0 : { *(SORT(___ksymtab_gpl+*)) }
+ __ksymtab_unused 0 : { *(SORT(___ksymtab_unused+*)) }
+ __ksymtab_unused_gpl 0 : { *(SORT(___ksymtab_unused_gpl+*)) }
+ __ksymtab_gpl_future 0 : { *(SORT(___ksymtab_gpl_future+*)) }
+ __kcrctab 0 : { *(SORT(___kcrctab+*)) }
+ __kcrctab_gpl 0 : { *(SORT(___kcrctab_gpl+*)) }
+ __kcrctab_unused 0 : { *(SORT(___kcrctab_unused+*)) }
+ __kcrctab_unused_gpl 0 : { *(SORT(___kcrctab_unused_gpl+*)) }
+ __kcrctab_gpl_future 0 : { *(SORT(___kcrctab_gpl_future+*)) }
}
--
1.7.10.4

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