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powerpc: Ensure dtl buffers do not cross 4k boundary

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Future releases of fimrware will enforce a requirement that DTL buffers
do not cross a 4k boundary. Commit
127493d5dc satisfies this requirement for
CONFIG_VIRT_CPU_ACCOUNTING=y kernels, but if !CONFIG_VIRT_CPU_ACCOUNTING
&& CONFIG_DTL=y, the current code will fail at dtl registration time.
Fix this by making the kmem cache from
127493d5dc visible outside of setup.c and
using the same cache in both dtl.c and setup.c. This requires a bit of
reorganization to ensure ordering of the kmem cache and buffer
allocations.

Note: Since firmware now limits the size of the buffer, I made
dtl_buf_entries read-only in debugfs.

Tested with upcoming firmware with the 4 combinations of
CONFIG_VIRT_CPU_ACCOUNTING and CONFIG_DTL.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Anton Blanchard <anton@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Nishanth Aravamudan
2011-05-04 12:54:16 +00:00
committed by Benjamin Herrenschmidt
parent 767303349e
commit af442a1baa
3 changed files with 35 additions and 18 deletions
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2
arch/powerpc/include/asm/lppaca.h
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@@ -210,6 +210,8 @@ struct dtl_entry {
#define DISPATCH_LOG_BYTES 4096 /* bytes per cpu */
#define N_DISPATCH_LOG (DISPATCH_LOG_BYTES / sizeof(struct dtl_entry))
extern struct kmem_cache *dtl_cache;
/*
* When CONFIG_VIRT_CPU_ACCOUNTING = y, the cpu accounting code controls
* reading from the dispatch trace log. If other code wants to consume