From: Christophe Leroy <christophe.leroy@csgroup.eu>
To: Jordan Niethe <jniethe5@gmail.com>, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc: Allow relative pointers in bug table entries
Date: Sat, 28 Nov 2020 20:00:24 +0100 [thread overview]
Message-ID: <5c997bc4-c859-0db6-f167-37ca37819059@csgroup.eu> (raw)
In-Reply-To: <20201127030238.763-1-jniethe5@gmail.com>
Le 27/11/2020 à 04:02, Jordan Niethe a écrit :
> This enables GENERIC_BUG_RELATIVE_POINTERS on Power so that 32-bit
> offsets are stored in the bug entries rather than 64-bit pointers.
>
> Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
> ---
> arch/powerpc/Kconfig | 4 ++++
> arch/powerpc/include/asm/bug.h | 37 ++++++++++++++++++++++++++++++++--
> arch/powerpc/xmon/xmon.c | 17 ++++++++++++++--
> 3 files changed, 54 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index e9f13fe08492..294108e0e5c6 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -311,6 +311,10 @@ config GENERIC_BUG
> default y
> depends on BUG
>
> +config GENERIC_BUG_RELATIVE_POINTERS
> + def_bool y
> + depends on GENERIC_BUG
> +
> config SYS_SUPPORTS_APM_EMULATION
> default y if PMAC_APM_EMU
> bool
> diff --git a/arch/powerpc/include/asm/bug.h b/arch/powerpc/include/asm/bug.h
> index 338f36cd9934..d03d834042a1 100644
> --- a/arch/powerpc/include/asm/bug.h
> +++ b/arch/powerpc/include/asm/bug.h
> @@ -12,7 +12,11 @@
> #ifdef CONFIG_DEBUG_BUGVERBOSE
> .macro EMIT_BUG_ENTRY addr,file,line,flags
> .section __bug_table,"aw"
> +#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
As far as I understand, as soon as CONFIG_BUG is selected, GENERIC_BUG is automatically selected so
GENERIC_BUG_RELATIVE_POINTERS is selected as well. Therefore this #ifndef is never possible.
> 5001: PPC_LONG \addr, 5002f
> +#else
> +5001: .4byte \addr - 5001b, 5002f - 5001b
> +#endif /* CONFIG_GENERIC_BUG_RELATIVE_POINTERS */
> .short \line, \flags
> .org 5001b+BUG_ENTRY_SIZE
> .previous
> @@ -23,7 +27,11 @@
> #else
> .macro EMIT_BUG_ENTRY addr,file,line,flags
> .section __bug_table,"aw"
> +#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
Same
> 5001: PPC_LONG \addr
> +#else
> +5001: .4byte \addr - 5001b
> +#endif /* CONFIG_GENERIC_BUG_RELATIVE_POINTERS */
> .short \flags
> .org 5001b+BUG_ENTRY_SIZE
> .previous
> @@ -34,20 +42,45 @@
> /* _EMIT_BUG_ENTRY expects args %0,%1,%2,%3 to be FILE, LINE, flags and
> sizeof(struct bug_entry), respectively */
> #ifdef CONFIG_DEBUG_BUGVERBOSE
> +#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
Same
> #define _EMIT_BUG_ENTRY \
> ".section __bug_table,\"aw\"\n" \
> "2:\t" PPC_LONG "1b, %0\n" \
> "\t.short %1, %2\n" \
> ".org 2b+%3\n" \
> ".previous\n"
> -#else
> +
> +#else /* relative pointers */
> +
> +#define _EMIT_BUG_ENTRY \
> + ".section __bug_table,\"aw\"\n" \
> + "2:\t.4byte 1b - 2b, %0 - 2b\n" \
> + "\t.short %1, %2\n" \
> + ".org 2b+%3\n" \
> + ".previous\n"
> +#endif /* relative pointers */
> +
> +#else /* verbose */
> +
> +#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
Same
> #define _EMIT_BUG_ENTRY \
> ".section __bug_table,\"aw\"\n" \
> "2:\t" PPC_LONG "1b\n" \
> "\t.short %2\n" \
> ".org 2b+%3\n" \
> ".previous\n"
> -#endif
> +
> +#else /* relative pointers */
> +
> +#define _EMIT_BUG_ENTRY \
> + ".section __bug_table,\"aw\"\n" \
> + "2:\t.4byte 1b - 2b\n" \
> + "\t.short %2\n" \
> + ".org 2b+%3\n" \
> + ".previous\n"
> +
> +#endif /* relative pointers */
> +#endif /* verbose */
>
> #define BUG_ENTRY(insn, flags, ...) \
> __asm__ __volatile__( \
> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
> index 55c43a6c9111..5f7cf7e95767 100644
> --- a/arch/powerpc/xmon/xmon.c
> +++ b/arch/powerpc/xmon/xmon.c
> @@ -1731,6 +1731,9 @@ static void print_bug_trap(struct pt_regs *regs)
> #ifdef CONFIG_BUG
> const struct bug_entry *bug;
> unsigned long addr;
> +#ifdef CONFIG_DEBUG_BUGVERBOSE
> + char *file;
> +#endif
>
> if (regs->msr & MSR_PR)
> return; /* not in kernel */
> @@ -1744,10 +1747,20 @@ static void print_bug_trap(struct pt_regs *regs)
> return;
>
> #ifdef CONFIG_DEBUG_BUGVERBOSE
> +#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
Same
> + file = bug->file;
> +#else /* relative pointers */
> + file = (char *)bug + bug->file_disp;
> +#endif /* relative pointers */
> printf("kernel BUG at %s:%u!\n",
> - bug->file, bug->line);
> + file, bug->line);
> #else
> - printf("kernel BUG at %px!\n", (void *)bug->bug_addr);
> +#ifndef CONFIG_GENERIC_BUG_RELATIVE_POINTERS
Same
> + addr = bug->addr;
> +#else /* relative pointers */
> + addr = (unsigned long)bug + bug->bug_addr_disp;
> +#endif /* relative pointers */
> + printf("kernel BUG at %px!\n", (void *)addr);
> #endif
> #endif /* CONFIG_BUG */
> }
>
Christophe
next prev parent reply other threads:[~2020-11-28 19:02 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-27 3:02 [PATCH] powerpc: Allow relative pointers in bug table entries Jordan Niethe
2020-11-28 19:00 ` Christophe Leroy [this message]
2020-11-30 0:59 ` Jordan Niethe
2020-11-30 1:42 ` Michael Ellerman
2020-11-30 1:50 ` Jordan Niethe
2020-11-30 6:27 ` Christophe Leroy
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