[PATCH 17/19] ARM: Correct BUG() assembly to ensure it is endian-agnostic
Dave Martin
Dave.Martin at arm.com
Wed Aug 28 12:48:46 EDT 2013
On Tue, Aug 27, 2013 at 10:38:27PM +0100, Ben Dooks wrote:
> 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 at arm.com>).
Reviewed-by: Dave Martin <Dave.Martin at arm.com>
>
> Signed-off-by: Ben Dooks <ben.dooks at codethink.co.uk>
> ---
> arch/arm/include/asm/bug.h | 10 ++++++----
> arch/arm/kernel/traps.c | 8 +++++---
> 2 files changed, 11 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm/include/asm/bug.h b/arch/arm/include/asm/bug.h
> index 7af5c6c..b274bde 100644
> --- a/arch/arm/include/asm/bug.h
> +++ b/arch/arm/include/asm/bug.h
> @@ -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 */
> diff --git a/arch/arm/kernel/traps.c b/arch/arm/kernel/traps.c
> index 99bcd0e3..da070db 100644
> --- a/arch/arm/kernel/traps.c
> +++ b/arch/arm/kernel/traps.c
> @@ -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
> --
> 1.7.10.4
>
>
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