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Commit 63328070 authored by Ben Dooks's avatar Ben Dooks
Browse files

ARM: Correct BUG() assembly to ensure it is endian-agnostic 



Currently BUG() uses .word or .hword to create the necessary illegal
instructions. However if we are building BE8 then these get swapped
by the linker into different illegal instructions in the text. This
means that the BUG() macro does not get trapped properly.

Change to using <asm/opcodes.h> to provide the necessary ARM instruction
building as we cannot rely on gcc/gas having the `.inst` instructions
which where added to try and resolve this issue (reported by Dave Martin
<Dave.Martin@arm.com>).

Signed-off-by: default avatarBen Dooks <ben.dooks@codethink.co.uk>
Reviewed-by: default avatarDave Martin <Dave.Martin@arm.com>
parent 3460743e

arch/arm/include/asm/bug.h

+6 −4
Original line number Diff line number Diff line
@@ -2,6 +2,8 @@ 
#define _ASMARM_BUG_H



#include <linux/linkage.h>

#include <linux/types.h>

#include <asm/opcodes.h>



#ifdef CONFIG_BUG
@@ -12,10 +14,10 @@ 
 */

#ifdef CONFIG_THUMB2_KERNEL

#define BUG_INSTR_VALUE 0xde02

#define BUG_INSTR_TYPE ".hword "

#define BUG_INSTR(__value) __inst_thumb16(__value)

#else

#define BUG_INSTR_VALUE 0xe7f001f2

#define BUG_INSTR_TYPE ".word "

#define BUG_INSTR(__value) __inst_arm(__value)

#endif
@@ -33,7 +35,7 @@ 


#define __BUG(__file, __line, __value)				\

do {								\

	asm volatile("1:\t" BUG_INSTR_TYPE #__value "\n"	\

	asm volatile("1:\t" BUG_INSTR(__value) "\n"  \

		".pushsection .rodata.str, \"aMS\", %progbits, 1\n" \

		"2:\t.asciz " #__file "\n" 			\

		".popsection\n" 				\
@@ -48,7 +50,7 @@ do { \ 


#define __BUG(__file, __line, __value)				\

do {								\

	asm volatile(BUG_INSTR_TYPE #__value);			\

	asm volatile(BUG_INSTR(__value) "\n");			\

	unreachable();						\

} while (0)

#endif  /* CONFIG_DEBUG_BUGVERBOSE */

arch/arm/kernel/traps.c

+5 −3
Original line number Diff line number Diff line
@@ -342,15 +342,17 @@ void arm_notify_die(const char *str, struct pt_regs *regs, 
int is_valid_bugaddr(unsigned long pc)

{

#ifdef CONFIG_THUMB2_KERNEL

	unsigned short bkpt;

	u16 bkpt;

	u16 insn = __opcode_to_mem_thumb16(BUG_INSTR_VALUE);

#else

	unsigned long bkpt;

	u32 bkpt;

	u32 insn = __opcode_to_mem_arm(BUG_INSTR_VALUE);

#endif



	if (probe_kernel_address((unsigned *)pc, bkpt))

		return 0;



	return bkpt == BUG_INSTR_VALUE;

	return bkpt == insn;

}



#endif