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

[Jordan Niethe]

On Tue, Apr 28, 2020 at 3:20 PM Christophe Leroy
<christophe.leroy at 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 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 ?
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