[PATCH v6 03/28] powerpc/xmon: Move breakpoints to text section

[Christophe Leroy]

Le 28/04/2020 à 03:57, Jordan Niethe a écrit :
> The instructions for xmon's breakpoint are stored bpt_table[] which is in
> the data section. This is problematic as the data section may be marked
> as no execute. Move bpt_table[] to the text section.
> 
> Signed-off-by: Jordan Niethe <jniethe5 at gmail.com>
> ---
> v6: - New to series. Was part of the previous patch.
>      - Make BPT_SIZE available in assembly
> ---
>   arch/powerpc/kernel/asm-offsets.c |  8 ++++++++
>   arch/powerpc/xmon/Makefile        |  2 +-
>   arch/powerpc/xmon/xmon.c          |  6 +-----
>   arch/powerpc/xmon/xmon_bpts.S     |  9 +++++++++
>   arch/powerpc/xmon/xmon_bpts.h     | 14 ++++++++++++++
>   5 files changed, 33 insertions(+), 6 deletions(-)
>   create mode 100644 arch/powerpc/xmon/xmon_bpts.S
>   create mode 100644 arch/powerpc/xmon/xmon_bpts.h
> 
> diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
> index c25e562f1cd9..2401f415f423 100644
> --- a/arch/powerpc/kernel/asm-offsets.c
> +++ b/arch/powerpc/kernel/asm-offsets.c
> @@ -70,6 +70,10 @@
>   #include <asm/fixmap.h>
>   #endif
>   
> +#ifdef CONFIG_XMON
> +#include "../xmon/xmon_bpts.h"
> +#endif
> +
>   #define STACK_PT_REGS_OFFSET(sym, val)	\
>   	DEFINE(sym, STACK_FRAME_OVERHEAD + offsetof(struct pt_regs, val))
>   
> @@ -783,5 +787,9 @@ int main(void)
>   	DEFINE(VIRT_IMMR_BASE, (u64)__fix_to_virt(FIX_IMMR_BASE));
>   #endif
>   
> +#ifdef CONFIG_XMON
> +	DEFINE(BPT_SIZE, BPT_SIZE);
> +#endif
> +
>   	return 0;
>   }
> diff --git a/arch/powerpc/xmon/Makefile b/arch/powerpc/xmon/Makefile
> index c3842dbeb1b7..515a13ea6f28 100644
> --- a/arch/powerpc/xmon/Makefile
> +++ b/arch/powerpc/xmon/Makefile
> @@ -21,7 +21,7 @@ endif
>   
>   ccflags-$(CONFIG_PPC64) := $(NO_MINIMAL_TOC)
>   
> -obj-y			+= xmon.o nonstdio.o spr_access.o
> +obj-y			+= xmon.o nonstdio.o spr_access.o xmon_bpts.o
>   
>   ifdef CONFIG_XMON_DISASSEMBLY
>   obj-y			+= ppc-dis.o ppc-opc.o
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index a064392df1b8..f7ce3ea8694c 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -62,6 +62,7 @@
>   
>   #include "nonstdio.h"
>   #include "dis-asm.h"
> +#include "xmon_bpts.h"
>   
>   #ifdef CONFIG_SMP
>   static cpumask_t cpus_in_xmon = CPU_MASK_NONE;
> @@ -108,7 +109,6 @@ struct bpt {
>   #define BP_TRAP		2
>   #define BP_DABR		4
>   
> -#define NBPTS	256
>   static struct bpt bpts[NBPTS];
>   static struct bpt dabr;
>   static struct bpt *iabr;
> @@ -116,10 +116,6 @@ static unsigned bpinstr = 0x7fe00008;	/* trap */
>   
>   #define BP_NUM(bp)	((bp) - bpts + 1)
>   
> -#define BPT_SIZE       (sizeof(unsigned int) * 2)
> -#define BPT_WORDS      (BPT_SIZE / sizeof(unsigned int))
> -static unsigned int bpt_table[NBPTS * BPT_WORDS];
> -
>   /* Prototypes */
>   static int cmds(struct pt_regs *);
>   static int mread(unsigned long, void *, int);
> diff --git a/arch/powerpc/xmon/xmon_bpts.S b/arch/powerpc/xmon/xmon_bpts.S
> new file mode 100644
> index 000000000000..f3ad0ab50854
> --- /dev/null
> +++ b/arch/powerpc/xmon/xmon_bpts.S
> @@ -0,0 +1,9 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#include <asm/ppc_asm.h>
> +#include <asm/asm-compat.h>
> +#include <asm/asm-offsets.h>
> +#include "xmon_bpts.h"
> +
> +.global bpt_table
> +bpt_table:
> +	.space NBPTS * BPT_SIZE

No alignment required ? Standard alignment (probably 4 bytes ?) is 
acceptable ?


> diff --git a/arch/powerpc/xmon/xmon_bpts.h b/arch/powerpc/xmon/xmon_bpts.h
> new file mode 100644
> index 000000000000..b7e94375db86
> --- /dev/null
> +++ b/arch/powerpc/xmon/xmon_bpts.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef XMON_BPTS_H
> +#define XMON_BPTS_H
> +
> +#define NBPTS	256
> +#ifndef __ASSEMBLY__
> +#define BPT_SIZE	(sizeof(unsigned int) * 2)
> +#define BPT_WORDS	(BPT_SIZE / sizeof(unsigned int))
> +
> +extern unsigned int bpt_table[NBPTS * BPT_WORDS];
> +
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* XMON_BPTS_H */
> 

Christophe