Re: [RFC GIT PULL] hw-breakpoints: Rewrite on top of perf counters
From: Frederic Weisbecker
Date: Thu Sep 10 2009 - 14:24:19 EST
On Thu, Sep 10, 2009 at 08:09:56PM +1000, Paul Mackerras wrote:
>
Frederic Weisbecker writes:
>
>
> This is a rewrite of the hardware breakpoints on top of perf counters.
>
>
On powerpc, it doesn't build. I get:
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>
CC kernel/perf_counter.o
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kernel/perf_counter.c:31:31: error: asm/hw_breakpoint.h: No such file or directory
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kernel/perf_counter.c: In function 'bp_perf_counter_init':
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kernel/perf_counter.c:3964: error: implicit declaration of function 'register_perf_hw_breakpoint'
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kernel/perf_counter.c:3966: error: implicit declaration of function '__register_perf_hw_breakpoint'
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kernel/perf_counter.c:3968: error: 'perf_ops_bp' undeclared (first use in this function)
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kernel/perf_counter.c:3968: error: (Each undeclared identifier is reported only once
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kernel/perf_counter.c:3968: error: for each function it appears in.)
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make[2]: *** [kernel/perf_counter.o] Error 1
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make[1]: *** [kernel] Error 2
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make: *** [sub-make] Error 2
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>
Seems like every architecture now needs an asm/hw_breakpoint.h. What
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is the minimum required in that file? Looks like we would require a
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perf_ops_bp, at least.
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>
Could you please either arrange things so that architectures that
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don't have hardware breakpoints hooked up to perf_counters don't need
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an asm/hw_breakpoint.h, or add minimal versions of that file for every
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architecture, so as not to break bisection unnecessarily?
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>
Paul.
I focused so much on the breakpoint <- perf dependency that I've even
forgotten the opposite dependency :)
I'll fix it in the 3rd patch.
We have an <asm-generic/hw-breakpoint.h> so I can just add an
#ifdef HAVE_HW_BREAKPOINT on its top.
Also I'll export the various breakpoints api dependant out of
kernel/perf_counter.c and provide stubs for the off-case.
Thanks.
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