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

Message ID	20200428015814.15380-4-jniethe5@gmail.com (mailing list archive)
State	Superseded
Headers	show Return-Path: <linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org> From: Jordan Niethe <jniethe5@gmail.com> To: linuxppc-dev@lists.ozlabs.org Subject: [PATCH v6 03/28] powerpc/xmon: Move breakpoints to text section Date: Tue, 28 Apr 2020 11:57:49 +1000 Message-Id: <20200428015814.15380-4-jniethe5@gmail.com> In-Reply-To: <20200428015814.15380-1-jniethe5@gmail.com> References: <20200428015814.15380-1-jniethe5@gmail.com> Precedence: list Cc: alistair@popple.id.au, npiggin@gmail.com, bala24@linux.ibm.com, Jordan Niethe <jniethe5@gmail.com>, dja@axtens.net Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" <linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org>
Series	Initial Prefixed Instruction support \| expand [v6,00/28] Initial Prefixed Instruction support [v6,01/28] powerpc/xmon: Remove store_inst() for patch_instruction() [v6,02/28] powerpc/xmon: Move breakpoint instructions to own array [v6,03/28] powerpc/xmon: Move breakpoints to text section [v6,04/28] powerpc/xmon: Use bitwise calculations in_breakpoint_table() [v6,05/28] powerpc: Change calling convention for create_branch() et. al. [v6,06/28] powerpc: Use a macro for creating instructions from u32s [v6,07/28] powerpc: Use an accessor for instructions [v6,08/28] powerpc: Use a function for getting the instruction op code [v6,09/28] powerpc: Use a function for byte swapping instructions [v6,10/28] powerpc: Introduce functions for instruction equality [v6,11/28] powerpc: Use a datatype for instructions [v6,12/28] powerpc: Use a function for reading instructions [v6,13/28] powerpc: Add a probe_user_read_inst() function [v6,14/28] powerpc: Add a probe_kernel_read_inst() function [v6,15/28] powerpc/kprobes: Use patch_instruction() [v6,16/28] powerpc: Define and use __get_user_instr{, inatomic}() [v6,17/28] powerpc: Introduce a function for reporting instruction length [v6,18/28] powerpc/xmon: Use a function for reading instructions [v6,19/28] powerpc/xmon: Move insertion of breakpoint for xol'ing [v6,20/28] powerpc: Make test_translate_branch() independent of instruction length [v6,21/28] powerpc: Enable Prefixed Instructions [v6,22/28] powerpc: Define new SRR1 bits for a future ISA version [v6,23/28] powerpc: Add prefixed instructions to instruction data type [v6,24/28] powerpc: Test prefixed code patching [v6,25/28] powerpc: Test prefixed instructions in feature fixups [v6,26/28] powerpc: Support prefixed instructions in alignment handler [v6,27/28] powerpc sstep: Add support for prefixed load/stores [v6,28/28] powerpc sstep: Add support for prefixed fixed-point arithmetic

Context	Check	Description
snowpatch_ozlabs/apply_patch	success	Successfully applied on branch powerpc/merge (54dc28ff5e0b3585224d49a31b53e030342ca5c3)
snowpatch_ozlabs/checkpatch	success	total: 0 errors, 0 warnings, 0 checks, 74 lines checked
snowpatch_ozlabs/needsstable	success	Patch has no Fixes tags

Jordan Niethe April 28, 2020, 1:57 a.m. UTC

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@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

Christophe Leroy April 28, 2020, 5:19 a.m. UTC | #1

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@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

Jordan Niethe April 28, 2020, 5:30 a.m. UTC | #2

On Tue, Apr 28, 2020 at 3:20 PM Christophe Leroy
<christophe.leroy@c-s.fr> wrote:
>
>
>
> 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@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 ?
No, I'll add a .balign    4 to be sure.
>
>
> > 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

Christophe Leroy April 28, 2020, 5:36 a.m. UTC | #3

Le 28/04/2020 à 07:30, Jordan Niethe a écrit :
> On Tue, Apr 28, 2020 at 3:20 PM Christophe Leroy
> <christophe.leroy@c-s.fr> wrote:
>>
>>
>>
>> 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@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 ?
> No, I'll add a .balign    4 to be sure.

I think it is aligned to 4 by default. My question was to know whether 4 
is enough.
I see BPT_SIZE is 8, should the alignment be at least 8 ?

>>
>>
>>> 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

Jordan Niethe April 29, 2020, 2:45 a.m. UTC | #4

On Tue, Apr 28, 2020 at 3:36 PM Christophe Leroy
<christophe.leroy@c-s.fr> wrote:
>
>
>
> Le 28/04/2020 à 07:30, Jordan Niethe a écrit :
> > On Tue, Apr 28, 2020 at 3:20 PM Christophe Leroy
> > <christophe.leroy@c-s.fr> wrote:
> >>
> >>
> >>
> >> 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@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 ?
> > No, I'll add a .balign    4 to be sure.
>
> I think it is aligned to 4 by default. My question was to know whether 4
> is enough.
> I see BPT_SIZE is 8, should the alignment be at least 8 ?
At this point each breakpoint entry is two instructions: the
instruction that has been replaced by a breakpoint and a trap
instruction after that. So I think it should be fine aligned to 4. In
the patch that introduces prefixed instructions to the data type, the
alignment changes.
>
> >>
> >>
> >>> 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

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

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