Date: Wed, 27 May 2026 15:24:09 +0000 From: Andrew Turner <andrew@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: a780d21eab97 - main - arm64: Support changing the DMAP memory type Message-ID: <6a170c99.27186.58925c24@gitrepo.freebsd.org>
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The branch main has been updated by andrew: URL: https://cgit.FreeBSD.org/src/commit/?id=a780d21eab9724b0667df84b02074994595d51c7 commit a780d21eab9724b0667df84b02074994595d51c7 Author: Andrew Turner <andrew@FreeBSD.org> AuthorDate: 2026-05-15 15:16:57 +0000 Commit: Andrew Turner <andrew@FreeBSD.org> CommitDate: 2026-05-27 15:22:25 +0000 arm64: Support changing the DMAP memory type When MTE is enabled we will use the DMAP to manage tags. To be able to read/write them we need to change the memory attribute to VM_MEMATTR_TAGGED. Support changing the DMAP memory type to values known to have equivalent cache properties. Sponsored by: Arm Ltd Differential Revision: https://reviews.freebsd.org/D55949 --- sys/arm64/arm64/pmap.c | 64 ++++++++++++++++++++++++++++++++++++++---------- sys/arm64/include/pmap.h | 1 + 2 files changed, 52 insertions(+), 13 deletions(-) diff --git a/sys/arm64/arm64/pmap.c b/sys/arm64/arm64/pmap.c index adc583812e5b..fd4232711697 100644 --- a/sys/arm64/arm64/pmap.c +++ b/sys/arm64/arm64/pmap.c @@ -358,6 +358,7 @@ struct pv_chunks_list __exclusive_cache_line pv_chunks[PMAP_MEMDOM]; vm_paddr_t dmap_phys_base; /* The start of the dmap region */ vm_paddr_t dmap_phys_max; /* The limit of the dmap region */ vm_offset_t dmap_max_addr; /* The virtual address limit of the dmap */ +static int dmap_attr = VM_MEMATTR_WRITE_BACK; extern pt_entry_t pagetable_l0_ttbr1[]; @@ -483,7 +484,7 @@ static void pmap_abort_ptp(pmap_t pmap, vm_offset_t va, vm_page_t mpte); static bool pmap_activate_int(struct thread *td, pmap_t pmap); static void pmap_alloc_asid(pmap_t pmap); static int pmap_change_props_locked(void *addr, vm_size_t size, - vm_prot_t prot, int mode, bool skip_unmapped); + vm_prot_t prot, int mode, int old_mode, bool skip_unmapped); static bool pmap_copy_l3c(pmap_t pmap, pt_entry_t *l3p, vm_offset_t va, pt_entry_t l3e, vm_page_t ml3, struct rwlock **lockp); static pt_entry_t *pmap_demote_l1(pmap_t pmap, pt_entry_t *l1, vm_offset_t va); @@ -8161,7 +8162,7 @@ pmap_unmapbios(void *p, vm_size_t size) /* Ensure the attributes are as expected for the DMAP region */ PMAP_LOCK(kernel_pmap); error = pmap_change_props_locked(va, size, - PROT_READ | PROT_WRITE, VM_MEMATTR_DEFAULT, false); + PROT_READ | PROT_WRITE, VM_MEMATTR_DEFAULT, -1, false); PMAP_UNLOCK(kernel_pmap); KASSERT(error == 0, ("%s: Failed to reset DMAP attributes: %d", __func__, error)); @@ -8267,7 +8268,25 @@ pmap_change_attr(void *va, vm_size_t size, int mode) int error; PMAP_LOCK(kernel_pmap); - error = pmap_change_props_locked(va, size, PROT_NONE, mode, false); + error = pmap_change_props_locked(va, size, PROT_NONE, mode, -1, false); + PMAP_UNLOCK(kernel_pmap); + return (error); +} + +int +pmap_change_dmap_attr(int mode) +{ + int error; + + KASSERT(mode == VM_MEMATTR_WRITE_BACK || + mode == VM_MEMATTR_TAGGED, + ("%s: mode %d must be compatible with write-back", __func__, mode)); + + PMAP_LOCK(kernel_pmap); + error = pmap_change_props_locked((void *)DMAP_MIN_ADDRESS, + dmap_max_addr - DMAP_MIN_ADDRESS, PROT_NONE, mode, dmap_attr, true); + if (error == 0) + dmap_attr = mode; PMAP_UNLOCK(kernel_pmap); return (error); } @@ -8289,20 +8308,20 @@ pmap_change_prot(void *va, vm_size_t size, vm_prot_t prot) return (EINVAL); PMAP_LOCK(kernel_pmap); - error = pmap_change_props_locked(va, size, prot, -1, false); + error = pmap_change_props_locked(va, size, prot, -1, -1, false); PMAP_UNLOCK(kernel_pmap); return (error); } static int pmap_change_props_locked(void *addr, vm_size_t size, vm_prot_t prot, - int mode, bool skip_unmapped) + int mode, int old_mode, bool skip_unmapped) { vm_offset_t base, offset, tmpva, va; vm_size_t pte_size; vm_paddr_t pa; pt_entry_t pte, *ptep, *newpte; - pt_entry_t bits, mask; + pt_entry_t bits, mask, old_mode_bits, old_mode_mask; char *tmpptep; int lvl, rv; @@ -8316,8 +8335,8 @@ pmap_change_props_locked(void *addr, vm_size_t size, vm_prot_t prot, !(base >= VM_MIN_KERNEL_ADDRESS && base < VM_MAX_KERNEL_ADDRESS)) return (EINVAL); - bits = 0; - mask = 0; + bits = old_mode_bits = 0; + mask = old_mode_mask = 0; if (mode != -1) { bits = ATTR_S1_IDX(mode); mask = ATTR_S1_IDX_MASK; @@ -8326,6 +8345,10 @@ pmap_change_props_locked(void *addr, vm_size_t size, vm_prot_t prot, bits |= ATTR_S1_XN; } } + if (old_mode != -1) { + old_mode_bits = ATTR_S1_IDX(old_mode); + old_mode_mask = ATTR_S1_IDX_MASK; + } if (prot != VM_PROT_NONE) { /* Don't mark the DMAP as executable. It never is on arm64. */ if (VIRT_IN_DMAP(base)) { @@ -8353,11 +8376,14 @@ pmap_change_props_locked(void *addr, vm_size_t size, vm_prot_t prot, if (ptep == NULL && !skip_unmapped) { return (EINVAL); } else if ((ptep == NULL && skip_unmapped) || - (pmap_load(ptep) & mask) == bits) { + (pmap_load(ptep) & mask) == bits || + (pmap_load(ptep) & old_mode_mask) != old_mode_bits) { /* - * We already have the correct attribute or there - * is no memory mapped at this address and we are - * skipping unmapped memory. + * We already have one of the following meaning + * we can skip this memory region:: + * - No memory mapped at this address + * - The new attributes are already set + * - The expected attributes are incorrect */ switch (lvl) { default: @@ -8487,12 +8513,24 @@ pmap_change_props_locked(void *addr, vm_size_t size, vm_prot_t prot, pa = PTE_TO_PHYS(pte); if (!VIRT_IN_DMAP(tmpva) && PHYS_IN_DMAP(pa)) { + int dmap_mode; + + /* + * When booting on HW with MTE enabled we may + * need to swap to a tagged type for the DMAP + * to allow tags to be set through it. + */ + if (mode == VM_MEMATTR_WRITE_BACK) + dmap_mode = dmap_attr; + else + dmap_mode = mode; + /* * Keep the DMAP memory in sync. */ rv = pmap_change_props_locked( PHYS_TO_DMAP(pa), pte_size, - prot, mode, true); + prot, dmap_mode, old_mode, true); if (rv != 0) return (rv); } diff --git a/sys/arm64/include/pmap.h b/sys/arm64/include/pmap.h index 00b54a874e12..1d90e8d472f2 100644 --- a/sys/arm64/include/pmap.h +++ b/sys/arm64/include/pmap.h @@ -148,6 +148,7 @@ void pmap_activate_vm(pmap_t); void pmap_bootstrap_dmap(vm_size_t); void pmap_bootstrap(void); int pmap_change_attr(void *va, vm_size_t size, int mode); +int pmap_change_dmap_attr(int); int pmap_change_prot(void *va, vm_size_t size, vm_prot_t prot); void pmap_kenter(vm_offset_t sva, vm_size_t size, vm_paddr_t pa, int mode); void pmap_kenter_device(vm_offset_t, vm_size_t, vm_paddr_t);home | help
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