[PATCH 3.16 068/366] ARM: 8764/1: kgdb: fix NUMREGBYTES so that gdb_regs[] is the correct size

Ben Hutchings
2018-11-11T20:15:02Z

From: David Rivshin <DRivshin@allworx.com>

commit 76ed0b803a2ab793a1b27d1dfe0de7955282cd34 upstream.

NUMREGBYTES (which is used as the size for gdb_regs[]) is incorrectly
based on DBG_MAX_REG_NUM instead of GDB_MAX_REGS. DBG_MAX_REG_NUM
is the number of total registers, while GDB_MAX_REGS is the number
of 'unsigned longs' it takes to serialize those registers. Since
FP registers require 3 'unsigned longs' each, DBG_MAX_REG_NUM is
smaller than GDB_MAX_REGS.

This causes GDB 8.0 give the following error on connect:
"Truncated register 19 in remote 'g' packet"

This also causes the register serialization/deserialization logic
to overflow gdb_regs[], overwriting whatever follows.

Fixes: 834b2964b7ab ("kgdb,arm: fix register dump")
Signed-off-by: David Rivshin <drivshin@allworx.com>
Acked-by: Rabin Vincent <rabin@rab.in>
Tested-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
arch/arm/include/asm/kgdb.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/arm/include/asm/kgdb.h
+++ b/arch/arm/include/asm/kgdb.h
@@ -76,7 +76,7 @@ extern int kgdb_fault_expected;

#define KGDB_MAX_NO_CPUS 1
#define BUFMAX 400
-#define NUMREGBYTES (DBG_MAX_REG_NUM << 2)
+#define NUMREGBYTES (GDB_MAX_REGS << 2)
#define NUMCRITREGBYTES (32 << 2)

#define _R0 0