- 26 2月, 2011 1 次提交
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由 Will Deacon 提交于
ARMv7 allows the debug core logic to be powered down and provides the DBGPRSR register so that software can power-up and check the status of the logic. This patch ensures that the debug logic is powered up on ARMv7 cores before we attempt to access the extended debug registers. Signed-off-by: NWill Deacon <will.deacon@arm.com> Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
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- 12 2月, 2011 2 次提交
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由 Will Deacon 提交于
The ptrace debug information register was advertising breakpoint and watchpoint resources for unsupported debug architectures. This meant that setting breakpoints on these architectures would appear to succeed, although they would never fire in reality. This patch fixes the breakpoint slot probing so that it returns 0 when running on an unsupported debug architecture. Reported-by: NUlrich Weigand <ulrich.weigand@de.ibm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com> Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
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由 Will Deacon 提交于
Reading baseline CP14 registers, other than DBGDIDR, when the OS Lock is set leads to UNPREDICTABLE behaviour. This patch ensures that we clear the OS lock before accessing anything other than the DBGDIDR, thereby avoiding this behaviour. Signed-off-by: NWill Deacon <will.deacon@arm.com> Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
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- 15 12月, 2010 1 次提交
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由 Will Deacon 提交于
The debug registers can only be manipulated from software if monitor debug mode is enabled. On some cores, this can never be enabled (i.e. the corresponding bit in the DSCR is RAZ/WI). This patch ensures we can handle this hardware configuration and fail gracefully, rather than blow up the kernel during boot. Reported-by: NCyril Chemparathy <cyril@ti.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 06 12月, 2010 9 次提交
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由 Will Deacon 提交于
sparse doesn't like per-cpu accesses such as: static DEFINE_PER_CPU(struct perf_event *, foo[MAXLEN]); struct perf_event **bar = __get_cpu_var(foo); and shouts quite loudly about it: | warning: incorrect type in assignment (different modifiers) | expected struct perf_event **slots | got struct perf_event *[noderef] *<noident> This patch adds casts to these sorts of assignments in hw_breakpoint.c in order to silence the warnings. Reported-by: NRussell King <rmk+kernel@arm.linux.org.uk> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Will Deacon 提交于
Single-stepping a breakpoint requires us to disable it temporarily so that we don't get stuck in a recursive debug trap. With per-cpu breakpoints this presents a problem where an interrupt can be taken before the single-step has completed and a new task is eventually scheduled. This new task will not hit the breakpoint because it will have been disabled during the previous handling code. This patch disallows per-cpu breakpoints on ARM when an overflow handler is not present. A similar effect can be created by placing breakpoints on a shell and then running applications there. Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Will Deacon 提交于
The single-stepping code is currently different depending on whether we are stepping over a breakpoint or a watchpoint. There is no good reason for this, so let's sort it out. This patch adds functions for enabling/disabling single-step for a particular hw_breakpoint and integrates this with the exception handling code. Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Will Deacon 提交于
The watchpoint single-stepping code calls register_user_hw_breakpoint to register a mismatch breakpoint for stepping over the watchpoint. This is performed with preemption disabled, which is unsafe as we may end up scheduling whilst in_atomic(). Furthermore, using the perf API is rather overkill since we are already in the hw-breakpoint backend and only require access to reserved breakpoints anyway. This patch reworks the watchpoint stepping code so that we don't require another perf_event for the mismatch breakpoint. Instead, we hold a separate arch_hw_breakpoint_ctrl struct inside the watchpoint which is used exclusively for stepping. We can check whether or not stepping is enabled when installing or uninstalling the watchpoint and operate on the breakpoint accordingly. Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Will Deacon 提交于
To permit handling of watchpoint exceptions without signalling a debugger, it is necessary to reserve breakpoint registers for in-kernel use only. This patch ensures that we record and subtract the number of reserved breakpoints from the number of usable breakpoint registers that we advertise to userspace via the ptrace API. Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Will Deacon 提交于
On ARM, debug exceptions occur in the form of data or prefetch aborts. One difference is that debug exceptions require access to per-cpu banked registers and data structures which are not saved in the low-level exception code. For kernels built with CONFIG_PREEMPT, there is an unlikely scenario that the debug handler ends up running on a different CPU from the one that originally signalled the event, resulting in random data being read from the wrong registers. This patch adds a debug_entry macro to the low-level exception handling code which checks whether the taken exception is a debug exception. If it is, the preempt count for the faulting process is incremented. After the debug handler has finished, the count is decremented. Acked-by: NCatalin Marinas <catalin.marinas@arm.com> Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Will Deacon 提交于
The current hw_breakpoint code tries to fix up the alignment of breakpoints so that we can make use of sparse byte-address-select bits in the control register and give the illusion that we can set breakpoints on unaligned addresses. Although this works on v6 cores, v7 forbids this behaviour, instead requiring breakpoints to be set on aligned addresses and have contiguous byte-address-select ranges depending on the instruction set in use. For ARM the only supported size is 4 bytes, whilst Thumb-2 also permits 2 byte breakpoints (watchpoints can be of 1, 2, 4 or 8 bytes long). This patch simplifies the alignment fixup code so that we require addresses to be aligned to the size of the corresponding breakpoint. This allows us to handle the common case of breaking on a half-word aligned Thumb-2 instruction and also allows us to set byte watchpoints on arbitrary addresses. Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Will Deacon 提交于
The ARMv7 debug architecture doesn't make any guarantees about the contents of debug control registers following a debug logic reset. This patch ensures that we reset the control registers when a cpu comes ONLINE (for example, with hotplug) so that when we enable monitor mode while inserting a breakpoint we won't exhibit random behaviour. Signed-off-by: NWill Deacon <will.deacon@arm.com>
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由 Will Deacon 提交于
ARMv7 architects a system for saving and restoring the debug registers across low-power modes. At the heart of this system is a lock register which, when set, forbids writes to the debug registers. While locked, writes to debug registers via the co-processor interface will result in undefined instruction traps. Linux currently doesn't make use of this feature because we update the debug registers on context switch anyway, however the status of the lock is IMPLEMENTATION DEFINED on reset. This patch ensures that the lock is cleared during boot so that we can write to the debug registers safely. Signed-off-by: NWill Deacon <will.deacon@arm.com>
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- 08 11月, 2010 1 次提交
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由 Joe Perches 提交于
Message isn't printed by WARN_ON. Signed-off-by: NJoe Perches <joe@perches.com> Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
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- 08 9月, 2010 1 次提交
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由 Will Deacon 提交于
The hw-breakpoint framework in the kernel requires architecture-specific support in order to install, remove, validate and manage hardware breakpoints. This patch adds initial support for this framework to the ARM architecture, but restricts the number of watchpoints to a single resource to get around the fact that the Data Fault Address Register is unknown when a watchpoint debug exception is taken. On cores with v7 debug, the Kernel can handle breakpoint and watchpoint exceptions occuring from userspace. Older cores require clients to handle the exception themselves by registering an appropriate overflow handler or, in the case of ptrace, handling the raised SIGTRAP. The memory-mapped extended debug interface is unsupported due to its unreliability in real implementations. Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: S. Karthikeyan <informkarthik@gmail.com> Signed-off-by: NWill Deacon <will.deacon@arm.com> Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>
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