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MIPS: scache: Fix scache init with invalid line size. 

In current scache init cache line_size is determined from
cpu config register, however if there there no scache
then mips_sc_probe_cm3 function populates a invalid line_size of 2.

The invalid line_size can cause a NULL pointer deference
during r4k_dma_cache_inv as r4k_blast_scache is populated
based on line_size. Scache line_size of 2 is invalid option in
r4k_blast_scache_setup.

This issue was faced during a MIPS I6400 based virtual platform bring up
where scache was not available in virtual platform model.

Signed-off-by: Govindraj Raja <Govindraj.Raja@imgtec.com>
Fixes: 7d53e9c4cd21("MIPS: CM3: Add support for CM3 L2 cache.")
Cc: Paul Burton <paul.burton@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hartley <James.Hartley@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org # v4.2+
Patchwork: https://patchwork.linux-mips.org/patch/12710/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Govindraj Raja 2016-02-29 11:41:20 +00:00 committed by Ralf Baechle
parent 51ff5d7767
commit 56fa81fc9a
1 changed files with 9 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
arch/mips/mm/sc-mips.c
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@ -164,11 +164,13 @@ static int __init mips_sc_probe_cm3(void)
sets = cfg & CM_GCR_L2_CONFIG_SET_SIZE_MSK;
sets >>= CM_GCR_L2_CONFIG_SET_SIZE_SHF;
c->scache.sets = 64 << sets;
if (sets)
c->scache.sets = 64 << sets;
line_sz = cfg & CM_GCR_L2_CONFIG_LINE_SIZE_MSK;
line_sz >>= CM_GCR_L2_CONFIG_LINE_SIZE_SHF;
c->scache.linesz = 2 << line_sz;
if (line_sz)
c->scache.linesz = 2 << line_sz;
assoc = cfg & CM_GCR_L2_CONFIG_ASSOC_MSK;
assoc >>= CM_GCR_L2_CONFIG_ASSOC_SHF;
@ -176,9 +178,12 @@ static int __init mips_sc_probe_cm3(void)
c->scache.waysize = c->scache.sets * c->scache.linesz;
c->scache.waybit = __ffs(c->scache.waysize);
c->scache.flags &= ~MIPS_CACHE_NOT_PRESENT;
if (c->scache.linesz) {
c->scache.flags &= ~MIPS_CACHE_NOT_PRESENT;
return 1;
}
return 1;
return 0;
}
static inline int __init mips_sc_probe(void)