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MIPS: Don't write ones to reserved entryhi bits.

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We've silently been relying on the hardware chopping off excess, reserved
ASID bits for no better reason that it saving an instruction.  Because we
already have:

#define cpu_asid(cpu, mm)       (cpu_context((cpu), (mm)) & ASID_MASK)

in <asm/mmu_context.h>.

We can use a cleanup to avoid writing non-zero bits into the reserved
entryhi bits.  This avoid triggering some debugging assertion in the
Cavium simulator.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Ralf Baechle 2009-05-27 17:29:37 +01:00
parent 22242681cf
commit d30cecbcbe
1 changed files with 5 additions and 5 deletions
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10
arch/mips/include/asm/mmu_context.h
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@ -165,12 +165,12 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
* having ASID_MASK smaller than the hardware maximum,
* make sure no "soft" bits become "hard"...
*/
write_c0_entryhi((read_c0_entryhi() & ~HW_ASID_MASK)
| (cpu_context(cpu, next) & ASID_MASK));
write_c0_entryhi((read_c0_entryhi() & ~HW_ASID_MASK) |
cpu_asid(cpu, next));
ehb(); /* Make sure it propagates to TCStatus */
evpe(mtflags);
#else
write_c0_entryhi(cpu_context(cpu, next));
write_c0_entryhi(cpu_asid(cpu, next));
#endif /* CONFIG_MIPS_MT_SMTC */
TLBMISS_HANDLER_SETUP_PGD(next->pgd);
@ -226,11 +226,11 @@ activate_mm(struct mm_struct *prev, struct mm_struct *next)
}
/* See comments for similar code above */
write_c0_entryhi((read_c0_entryhi() & ~HW_ASID_MASK) |
(cpu_context(cpu, next) & ASID_MASK));
cpu_asid(cpu, next));
ehb(); /* Make sure it propagates to TCStatus */
evpe(mtflags);
#else
write_c0_entryhi(cpu_context(cpu, next));
write_c0_entryhi(cpu_asid(cpu, next));
#endif /* CONFIG_MIPS_MT_SMTC */
TLBMISS_HANDLER_SETUP_PGD(next->pgd);