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MMU: Implement a vestigial partition table

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This implements a 1-entry partition table, so that instead of getting
the process table base address from the PRTBL SPR, the MMU now reads
the doubleword pointed to by the PTCR register plus 8 to get the
process table base address.  The partition table entry is cached.

Having the PTCR and the vestigial partition table reduces the amount
of software change required in Linux for Microwatt support.

Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
This commit is contained in:
Paul Mackerras
2021-06-17 20:01:32 +10:00
parent 84473eda1b
commit 18120f153d
14 changed files with 67 additions and 27 deletions
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9
tests/privileged/privileged.c
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@@ -14,7 +14,7 @@ extern int call_with_msr(unsigned long arg, int (*fn)(unsigned long), unsigned l
#define SRR0 26
#define SRR1 27
#define PID 48
#define PRTBL 720
#define PTCR 464
#define PVR 287
static inline unsigned long mfspr(int sprnum)
@@ -106,15 +106,18 @@ void zero_memory(void *ptr, unsigned long nbytes)
*/
unsigned long *pgdir = (unsigned long *) 0x10000;
unsigned long *proc_tbl = (unsigned long *) 0x12000;
unsigned long free_ptr = 0x13000;
unsigned long *part_tbl = (unsigned long *) 0x13000;
unsigned long free_ptr = 0x14000;
void init_mmu(void)
{
/* set up partition table */
store_pte(&part_tbl[1], (unsigned long)proc_tbl);
/* set up process table */
zero_memory(proc_tbl, 512 * sizeof(unsigned long));
/* RTS = 0 (2GB address space), RPDS = 10 (1024-entry top level) */
store_pte(&proc_tbl[2 * 1], (unsigned long) pgdir | 10);
mtspr(PRTBL, (unsigned long)proc_tbl);
mtspr(PTCR, (unsigned long)part_tbl);
mtspr(PID, 1);
zero_memory(pgdir, 1024 * sizeof(unsigned long));
}