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. Changes from v1: Avoid clearing of MIPS_CACHE_NOT_PRESENT if scache is absent https://patchwork.linux-mips.org/patch/12126/ Signed-off-by: Govindraj Raja <Govindraj.Raja@xxxxxxxxxx> --- arch/mips/mm/sc-mips.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/arch/mips/mm/sc-mips.c b/arch/mips/mm/sc-mips.c index 3bd0597..68c48f4 100644 --- a/arch/mips/mm/sc-mips.c +++ b/arch/mips/mm/sc-mips.c @@ -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; @@ -176,7 +178,8 @@ 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; } -- 2.5.0
