Date: Mon, 13 Apr 2026 14:24:04 +0000 Subject: git: c208439cdb58 - main - arm64: Add a cmap page to pmap Message-ID: <69dcfc84.46530.22f71c34@gitrepo.freebsd.org>
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The branch main has been updated by andrew: URL: https://cgit.FreeBSD.org/src/commit/?id=c208439cdb588d91aead9403cec3d4acf4a8bebf commit c208439cdb588d91aead9403cec3d4acf4a8bebf Author: Andrew Turner <andrew@FreeBSD.org> AuthorDate: 2026-04-13 11:50:32 +0000 Commit: Andrew Turner <andrew@FreeBSD.org> CommitDate: 2026-04-13 14:23:05 +0000 arm64: Add a cmap page to pmap When modifying mappings in pmap we may need to perform a break-before-make sequence. This creates an invalid mapping, then recreates it with the changes. When modifying DMAP mappings we may be changing the mapping that contains its own page table then after breaking the old entry we are unable to create the new entry. To fix this create a map that can be used & won't be affected by the break-before-make sequence. Reviewed by: kib Sponsored by: Arm Ltd Differential Revision: https://reviews.freebsd.org/D56306 --- sys/arm64/arm64/pmap.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c index 678030f827dd..7d19c927d369 100644 --- a/sys/arm64/arm64/pmap.c +++ b/sys/arm64/arm64/pmap.c @@ -290,6 +290,10 @@ VM_PAGE_TO_PV_LIST_LOCK(vm_page_t m) #define PTE_TO_VM_PAGE(pte) PHYS_TO_VM_PAGE(PTE_TO_PHYS(pte)) #define VM_PAGE_TO_PTE(m) PHYS_TO_PTE(VM_PAGE_TO_PHYS(m)) +static struct mtx cmap_lock; +static void *cmap1_addr; +static pt_entry_t *cmap1_pte; + /* * The presence of this flag indicates that the mapping is writeable. * If the ATTR_S1_AP_RO bit is also set, then the mapping is clean, otherwise @@ -1363,7 +1367,7 @@ pmap_bootstrap(void) virtual_avail = preinit_map_va + PMAP_PREINIT_MAPPING_SIZE; virtual_avail = roundup2(virtual_avail, L1_SIZE); - virtual_end = VM_MAX_KERNEL_ADDRESS - PMAP_MAPDEV_EARLY_SIZE; + virtual_end = VM_MAX_KERNEL_ADDRESS - PMAP_MAPDEV_EARLY_SIZE - L2_SIZE; kernel_vm_end = virtual_avail; /* @@ -1419,6 +1423,19 @@ pmap_bootstrap(void) alloc_pages(msgbufpv, round_page(msgbufsize) / PAGE_SIZE); msgbufp = (void *)msgbufpv; + /* Allocate space for the CPU0 CMAP */ + bs_state.va = virtual_end; + pmap_bootstrap_l2_table(&bs_state); + pmap_store(&bs_state.l3[pmap_l3_index(bs_state.va)], + PHYS_TO_PTE(pmap_early_vtophys((vm_offset_t)bs_state.l3)) | + ATTR_AF | pmap_sh_attr | ATTR_S1_XN | ATTR_KERN_GP | + ATTR_S1_IDX(VM_MEMATTR_WRITE_BACK) | L3_PAGE); + dsb(ishst); + + mtx_init(&cmap_lock, "SYSMAPS", NULL, MTX_DEF); + cmap1_addr = (void *)(virtual_end + L3_SIZE); + cmap1_pte = &bs_state.l3[pmap_l3_index((vm_offset_t)cmap1_addr)]; + pa = pmap_early_vtophys(bs_state.freemempos); physmem_exclude_region(start_pa, pa - start_pa, EXFLAG_NOALLOC);home | help
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