linux-kernel - [PATCH v3] cris: arch-v10: kgdb: Add '__used' for static variable is_dyn

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Date:	Thu, 6 Aug 2015 06:34:53 +0800
From:	Chen Gang <xili_gchen_5257@...mail.com>
To:	starvik@...s.com, jesper.nilsson@...s.com,
	Hans-Peter Nilsson <hans-peter.nilsson@...s.com>
CC:	linux-cris-kernel@...s.com,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH v3] cris: arch-v10: kgdb: Add '__used' for static variable
 is_dyn_brkp

Within one C file, current gcc can optimize the global static variables
according to the C code, but it will skip assembly code -- it will pass
them to gas directly.

if the static variable is used between C code and assembly code in one C
file (e.g. is_dyn_brkp in kgdb.c), it needs '__used' to let gcc know it
should be still used, or gcc may remove it for optimization.

The related error in this case:

    LD      init/built-in.o
  arch/cris/arch-v10/kernel/built-in.o: In function `kgdb_handle_breakpoint':
  (.text+0x2aca): undefined reference to `is_dyn_brkp'
  arch/cris/arch-v10/kernel/built-in.o: In function `is_static':
  kgdb.c:(.text+0x2ada): undefined reference to `is_dyn_brkp'

Signed-off-by: Chen Gang <gang.chen.5i5j@...il.com>
---
 arch/cris/arch-v10/kernel/kgdb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/cris/arch-v10/kernel/kgdb.c b/arch/cris/arch-v10/kernel/kgdb.c
index 5b61335..d554ae7 100644
--- a/arch/cris/arch-v10/kernel/kgdb.c
+++ b/arch/cris/arch-v10/kernel/kgdb.c
@@ -351,7 +351,7 @@ char internal_stack[INTERNAL_STACK_SIZE];
    breakpoint to be handled. A static breakpoint uses the content of register
    BRP as it is whereas a dynamic breakpoint requires subtraction with 2
    in order to execute the instruction. The first breakpoint is static. */
-static unsigned char is_dyn_brkp = 0;
+static unsigned char __used is_dyn_brkp;
 
 /********************************* String library ****************************/
 /* Single-step over library functions creates trap loops. */
-- 
1.9.3
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/