On 05.03.21 18:44, Catalin Marinas wrote:
On Fri, Mar 05, 2021 at 04:55:28PM +0100, David Hildenbrand wrote:
On 05.03.21 16:43, Catalin Marinas wrote:
On Fri, Mar 05, 2021 at 11:19:08AM +0000, Catalin Marinas wrote:
On Tue, Mar 02, 2021 at 08:21:03PM -0800, Patrick Daly wrote:
In a system which supports MTE, the linear kernel region must allow
reading/writing allocation tags. For memory present at boot this
is already being done in map_mem(). Add the same in arch_add_memory().
Signed-off-by: Patrick Daly <pdaly@xxxxxxxxxxxxxx>
---
arch/arm64/mm/mmu.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
index 9b25d60b..0fcfe90 100644
--- a/arch/arm64/mm/mmu.c
+++ b/arch/arm64/mm/mmu.c
@@ -1463,6 +1463,7 @@ int arch_add_memory(int nid, u64 start, u64 size,
struct mhp_params *params)
{
int ret, flags = 0;
+ pgprot_t pgprot;
if (!inside_linear_region(start, size)) {
pr_err("[%llx %llx] is outside linear mapping region\n", start, start + size);
@@ -1477,8 +1478,17 @@ int arch_add_memory(int nid, u64 start, u64 size,
IS_ENABLED(CONFIG_KFENCE))
flags = NO_BLOCK_MAPPINGS | NO_CONT_MAPPINGS;
+ /*
+ * The linear map must allow allocation tags reading/writing
+ * if MTE is present. Otherwise, it has the same attributes as
+ * PAGE_KERNEL.
+ */
+ pgprot = params->pgprot;
+ if (pgprot_val(pgprot) == pgprot_val(PAGE_KERNEL))
+ pgprot = PAGE_KERNEL_TAGGED;
+
__create_pgd_mapping(swapper_pg_dir, start, __phys_to_virt(start),
- size, params->pgprot, __pgd_pgtable_alloc,
+ size, pgprot, __pgd_pgtable_alloc,
flags);
[...]
---------------8<-------------------------------
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index e17b96d0e4b5..5c78b92d9ec5 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -486,6 +486,8 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd)
__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN)
#define pgprot_device(prot) \
__pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_DEVICE_nGnRE) | PTE_PXN | PTE_UXN)
+#define pgprot_tagged(prot) \
+ __pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_TAGGED))
/*
* DMA allocations for non-coherent devices use what the Arm architecture calls
* "Normal non-cacheable" memory, which permits speculation, unaligned accesses
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index cdfc4e9f253e..f5f5044db2ce 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -904,6 +904,10 @@ static inline void ptep_modify_prot_commit(struct vm_area_struct *vma,
#define pgprot_device pgprot_noncached
#endif
+#ifndef pgprot_tagged
+#define pgprot_tagged(prot) (prot)
+#endif
+
#ifdef CONFIG_MMU
#ifndef pgprot_modify
#define pgprot_modify pgprot_modify
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 5ba51a8bdaeb..4253d80a59ba 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1072,7 +1072,7 @@ static int online_memory_block(struct memory_block *mem, void *arg)
*/
int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
{
- struct mhp_params params = { .pgprot = PAGE_KERNEL };
+ struct mhp_params params = { .pgprot = pgprot_tagged(PAGE_KERNEL) };
This looks like we're pushing arch specific stuff ("tagged") in here. Can't
we generalize this to something like
pgprot_mhp_default
(or a better name)
that defaults to PAGE_KERNEL on all architectures except arm64 which
overwrites this somehow?
It works for me but I prefer the prot modification style similar to
pgprot_writecombine() etc. (i.e. takes a parameter like PAGE_KERNEL and
just changes bits of it).
Sure, I'm wondering if we can abstract the "tagged" part here.
pgprot_mhp(PAGE_KERNEL) whatsoever.
But maybe we do consider the "tagged" part okay in common code already
(it felt quite arm64 specific to me at first). I can spot
untagged_addr() all over the place. So maybe pgprot_tagged() is just fine.
--
Thanks,
David / dhildenb
