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ARCv2: PAE40: set MSB even if !CONFIG_ARC_HAS_PAE40 but PAE exists in SoC 

PAE40 confiuration in hardware extends some of the address registers
for TLB/cache ops to 2 words.

So far kernel was NOT setting the higher word if feature was not enabled
in software which is wrong. Those need to be set to 0 in such case.

Normally this would be done in the cache flush / tlb ops, however since
these registers only exist conditionally, this would have to be
conditional to a flag being set on boot which is expensive/ugly -
specially for the more common case of PAE exists but not in use.
Optimize that by zero'ing them once at boot - nobody will write to
them afterwards

Cc: stable@vger.kernel.org   #4.4+
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
This commit is contained in:
Vineet Gupta 2017-08-03 17:45:44 +05:30
parent 7d79cee2c6
commit b5ddb6d547
3 changed files with 41 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/arc/include/asm/mmu.h
View File

@ -94,6 +94,8 @@ static inline int is_pae40_enabled(void)
return IS_ENABLED(CONFIG_ARC_HAS_PAE40);
}
extern int pae40_exist_but_not_enab(void);
#endif /* !__ASSEMBLY__ */
#endif

34
arch/arc/mm/cache.c
View File

@ -1123,6 +1123,13 @@ noinline void __init arc_ioc_setup(void)
__dc_enable();
}
/*
* Cache related boot time checks/setups only needed on master CPU:
* - Geometry checks (kernel build and hardware agree: e.g. L1_CACHE_BYTES)
* Assume SMP only, so all cores will have same cache config. A check on
* one core suffices for all
* - IOC setup / dma callbacks only need to be done once
*/
void __init arc_cache_init_master(void)
{
unsigned int __maybe_unused cpu = smp_processor_id();
@ -1202,12 +1209,27 @@ void __ref arc_cache_init(void)
printk(arc_cache_mumbojumbo(0, str, sizeof(str)));
/*
* Only master CPU needs to execute rest of function:
* - Assume SMP so all cores will have same cache config so
* any geomtry checks will be same for all
* - IOC setup / dma callbacks only need to be setup once
*/
if (!cpu)
arc_cache_init_master();
/*
* In PAE regime, TLB and cache maintenance ops take wider addresses
* And even if PAE is not enabled in kernel, the upper 32-bits still need
* to be zeroed to keep the ops sane.
* As an optimization for more common !PAE enabled case, zero them out
* once at init, rather than checking/setting to 0 for every runtime op
*/
if (is_isa_arcv2() && pae40_exist_but_not_enab()) {
if (IS_ENABLED(CONFIG_ARC_HAS_ICACHE))
write_aux_reg(ARC_REG_IC_PTAG_HI, 0);
if (IS_ENABLED(CONFIG_ARC_HAS_DCACHE))
write_aux_reg(ARC_REG_DC_PTAG_HI, 0);
if (l2_line_sz) {
write_aux_reg(ARC_REG_SLC_RGN_END1, 0);
write_aux_reg(ARC_REG_SLC_RGN_START1, 0);
}
}
}

12
arch/arc/mm/tlb.c
View File

@ -104,6 +104,8 @@
/* A copy of the ASID from the PID reg is kept in asid_cache */
DEFINE_PER_CPU(unsigned int, asid_cache) = MM_CTXT_FIRST_CYCLE;
static int __read_mostly pae_exists;
/*
* Utility Routine to erase a J-TLB entry
* Caller needs to setup Index Reg (manually or via getIndex)
@ -784,7 +786,7 @@ void read_decode_mmu_bcr(void)
mmu->u_dtlb = mmu4->u_dtlb * 4;
mmu->u_itlb = mmu4->u_itlb * 4;
mmu->sasid = mmu4->sasid;
mmu->pae = mmu4->pae;
pae_exists = mmu->pae = mmu4->pae;
}
}
@ -809,6 +811,11 @@ char *arc_mmu_mumbojumbo(int cpu_id, char *buf, int len)
return buf;
}
int pae40_exist_but_not_enab(void)
{
return pae_exists && !is_pae40_enabled();
}
void arc_mmu_init(void)
{
char str[256];
@ -859,6 +866,9 @@ void arc_mmu_init(void)
/* swapper_pg_dir is the pgd for the kernel, used by vmalloc */
write_aux_reg(ARC_REG_SCRATCH_DATA0, swapper_pg_dir);
#endif
if (pae40_exist_but_not_enab())
write_aux_reg(ARC_REG_TLBPD1HI, 0);
}
/*