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powerpc/hw_breakpoints: Add DABRX cpu feature to fix 32-bit regression

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When introducing support for DABRX in 4474ef0, we broke older 32-bit CPUs
that don't have that register.

Some CPUs have a DABR but not DABRX.  Configuration are:
- No 32bit CPUs have DABRX but some have DABR.
- POWER4+ and below have the DABR but no DABRX.
- 970 and POWER5 and above have DABR and DABRX.
- POWER8 has DAWR, hence no DABRX.

This introduces CPU_FTR_DABRX and sets it on appropriate CPUs.  We use
the top 64 bits for CPU FTR bits since only 64 bit CPUs have this.

Processors that don't have the DABRX will still work as they will fall
back to software filtering these breakpoints via perf_exclude_event().

Signed-off-by: Michael Neuling <mikey@neuling.org>
Reported-by: "Gorelik, Jacob (335F)" <jacob.gorelik@jpl.nasa.gov>
cc: stable@vger.kernel.org (v3.9 only)
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Michael Neuling
2013-05-16 20:27:31 +00:00
committed by Benjamin Herrenschmidt
parent fb0fce3e55
commit 82a9f16adc
2 changed files with 12 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
arch/powerpc/kernel/process.c
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@@ -399,7 +399,8 @@ static inline int __set_dabr(unsigned long dabr, unsigned long dabrx)
static inline int __set_dabr(unsigned long dabr, unsigned long dabrx)
{
mtspr(SPRN_DABR, dabr);
mtspr(SPRN_DABRX, dabrx);
if (cpu_has_feature(CPU_FTR_DABRX))
mtspr(SPRN_DABRX, dabrx);
return 0;
}
#else