From: rob@ti•com (Rob Clark)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 0/2] Fix ptrace software breakpoints
Date: Mon, 26 Jul 2010 20:30:54 -0500 [thread overview]
Message-ID: <4C4E36CE.3080108@ti.com> (raw)
In-Reply-To: <1279209238-16234-1-git-send-email-will.deacon@arm.com>
On 07/15/2010 10:53 AM, Will Deacon wrote:
> When using GDB on a quad-core Cortex-A9 (Versatile Express) board, software
> breakpoints do not work if the inferior is scheduled onto a different CPU from
> the debugger.
>
> When GDB changes the code of another context via the ptrace POKETEXT mechanism,
> the I-cache must be invalidated before the inferior is allowed to resume. If a
> copy-on-write is triggered by the copy_to_user_page function, the new page
> mappings must be used by the inferior in order to pick up the new instructions.
>
> This patch series addresses this problem by:
>
> (a) Providing a workaround for a known TLB issue on some revisions of the Cortex-A9.
> (b) Performing correct I-cache invalidation in the flush_ptrace_access code.
>
> All feedback/comments/tested-bys welcome.
>
> Cc: Rob Clark<rob@ti•com>
> Cc: Catalin Marinas<catalin.marinas@arm•com>
>
> Will Deacon (2):
> ARM: errata: TLBIASIDIS and TLBIMVAIS operations can broadcast a
> faulty ASID
> ARM: flush_ptrace_access: invalidate all I-caches
>
> arch/arm/Kconfig | 12 ++++++++++++
> arch/arm/include/asm/tlbflush.h | 8 ++++++++
> arch/arm/mm/flush.c | 4 ++--
> 3 files changed, 22 insertions(+), 2 deletions(-)
>
Tested on omap4430 (cortex-a9 SMP).. with this patchset I have yet to
see it fail, in regular use nor in the test case I wrote to show the
problem (git://github.com/robclark/gdb-test.git). Without these
patches, I'd see SIGILL and missed breakpoints 90+% of the time in
regular use of gdb (basically gdb was unusable unless I booted with
nosmp or disabled cache), and 100% of the time in my gdb-test.
Tested-by: Rob Clark<rob@ti•com>
next prev parent reply other threads:[~2010-07-27 1:30 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-15 15:53 [PATCH 0/2] Fix ptrace software breakpoints Will Deacon
2010-07-15 15:53 ` [PATCH 1/2] ARM: errata: TLBIASIDIS and TLBIMVAIS operations can broadcast a faulty ASID Will Deacon
2010-07-15 15:53 ` [PATCH 2/2] ARM: flush_ptrace_access: invalidate all I-caches Will Deacon
2010-07-15 16:32 ` Russell King - ARM Linux
2010-07-15 16:43 ` Will Deacon
2010-07-15 16:54 ` Catalin Marinas
2010-07-19 16:23 ` Will Deacon
2010-08-04 11:24 ` Will Deacon
2010-07-15 16:21 ` [PATCH 1/2] ARM: errata: TLBIASIDIS and TLBIMVAIS operations can broadcast a faulty ASID Shilimkar, Santosh
2010-07-15 16:32 ` Will Deacon
2010-07-15 16:43 ` Shilimkar, Santosh
2010-07-16 4:15 ` [PATCH 0/2] Fix ptrace software breakpoints Rob Clark
2010-07-20 17:23 ` Will Deacon
2010-07-27 1:30 ` Rob Clark [this message]
2010-07-27 9:43 ` Will Deacon
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