Author: kib
Date: Tue Feb 26 09:51:53 2019
New Revision: 344573
URL: https://svnweb.freebsd.org/changeset/base/344573
Log:
MFC r344256:
amd64: cleanup pmap_init_pat().
Modified:
stable/12/sys/amd64/amd64/pmap.c
Directory Properties:
stable/12/ (props changed)
Modified: stable/12/sys/amd64/amd64/pmap.c
==============================================================================
--- stable/12/sys/amd64/amd64/pmap.c Tue Feb 26 09:45:44 2019
(r344572)
+++ stable/12/sys/amd64/amd64/pmap.c Tue Feb 26 09:51:53 2019
(r344573)
@@ -353,6 +353,7 @@ pt_entry_t pg_nx;
static SYSCTL_NODE(_vm, OID_AUTO, pmap, CTLFLAG_RD, 0, "VM/pmap parameters");
+/* Unused, kept for ABI stability on the stable branch. */
static int pat_works = 1;
SYSCTL_INT(_vm_pmap, OID_AUTO, pat_works, CTLFLAG_RD, &pat_works, 1,
"Is page attribute table fully functional?");
@@ -1222,7 +1223,6 @@ pmap_bootstrap(vm_paddr_t *firstaddr)
void
pmap_init_pat(void)
{
- int pat_table[PAT_INDEX_SIZE];
uint64_t pat_msr;
u_long cr0, cr4;
int i;
@@ -1233,45 +1233,32 @@ pmap_init_pat(void)
/* Set default PAT index table. */
for (i = 0; i < PAT_INDEX_SIZE; i++)
- pat_table[i] = -1;
- pat_table[PAT_WRITE_BACK] = 0;
- pat_table[PAT_WRITE_THROUGH] = 1;
- pat_table[PAT_UNCACHEABLE] = 3;
- pat_table[PAT_WRITE_COMBINING] = 3;
- pat_table[PAT_WRITE_PROTECTED] = 3;
- pat_table[PAT_UNCACHED] = 3;
+ pat_index[i] = -1;
+ pat_index[PAT_WRITE_BACK] = 0;
+ pat_index[PAT_WRITE_THROUGH] = 1;
+ pat_index[PAT_UNCACHEABLE] = 3;
+ pat_index[PAT_WRITE_COMBINING] = 6;
+ pat_index[PAT_WRITE_PROTECTED] = 5;
+ pat_index[PAT_UNCACHED] = 2;
- /* Initialize default PAT entries. */
+ /*
+ * Initialize default PAT entries.
+ * Leave the indices 0-3 at the default of WB, WT, UC-, and UC.
+ * Program 5 and 6 as WP and WC.
+ *
+ * Leave 4 and 7 as WB and UC. Note that a recursive page table
+ * mapping for a 2M page uses a PAT value with the bit 3 set due
+ * to its overload with PG_PS.
+ */
pat_msr = PAT_VALUE(0, PAT_WRITE_BACK) |
PAT_VALUE(1, PAT_WRITE_THROUGH) |
PAT_VALUE(2, PAT_UNCACHED) |
PAT_VALUE(3, PAT_UNCACHEABLE) |
PAT_VALUE(4, PAT_WRITE_BACK) |
- PAT_VALUE(5, PAT_WRITE_THROUGH) |
- PAT_VALUE(6, PAT_UNCACHED) |
+ PAT_VALUE(5, PAT_WRITE_PROTECTED) |
+ PAT_VALUE(6, PAT_WRITE_COMBINING) |
PAT_VALUE(7, PAT_UNCACHEABLE);
- if (pat_works) {
- /*
- * Leave the indices 0-3 at the default of WB, WT, UC-, and UC.
- * Program 5 and 6 as WP and WC.
- * Leave 4 and 7 as WB and UC.
- */
- pat_msr &= ~(PAT_MASK(5) | PAT_MASK(6));
- pat_msr |= PAT_VALUE(5, PAT_WRITE_PROTECTED) |
- PAT_VALUE(6, PAT_WRITE_COMBINING);
- pat_table[PAT_UNCACHED] = 2;
- pat_table[PAT_WRITE_PROTECTED] = 5;
- pat_table[PAT_WRITE_COMBINING] = 6;
- } else {
- /*
- * Just replace PAT Index 2 with WC instead of UC-.
- */
- pat_msr &= ~PAT_MASK(2);
- pat_msr |= PAT_VALUE(2, PAT_WRITE_COMBINING);
- pat_table[PAT_WRITE_COMBINING] = 2;
- }
-
/* Disable PGE. */
cr4 = rcr4();
load_cr4(cr4 & ~CR4_PGE);
@@ -1286,8 +1273,6 @@ pmap_init_pat(void)
/* Update PAT and index table. */
wrmsr(MSR_PAT, pat_msr);
- for (i = 0; i < PAT_INDEX_SIZE; i++)
- pat_index[i] = pat_table[i];
/* Flush caches and TLBs again. */
wbinvd();
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