| Message ID | 20201110144207.90693-2-nikos.nikoleris@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm: MMU extentions to enable litmus7 | expand |
Hi Nikos, On 11/10/20 2:42 PM, Nikos Nikoleris wrote: > From: Luc Maranget <Luc.Maranget@inria.fr> > > Add the mmu_get_pte() function that allows a test to get a pointer to > the PTE for a valid virtual address. Return NULL if the MMU is off. > > Signed-off-by: Nikos Nikoleris <nikos.nikoleris@arm.com> > Signed-off-by: Luc Maranget <Luc.Maranget@inria.fr> > Co-Developed-by: Nikos Nikoleris <nikos.nikoleris@arm.com> > Reviewed-by: Andrew Jones <drjones@redhat.com> > Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com> > --- > lib/arm/asm/mmu-api.h | 1 + > lib/arm/mmu.c | 32 +++++++++++++++++++++----------- > 2 files changed, 22 insertions(+), 11 deletions(-) > > diff --git a/lib/arm/asm/mmu-api.h b/lib/arm/asm/mmu-api.h > index 2bbe1fa..3d04d03 100644 > --- a/lib/arm/asm/mmu-api.h > +++ b/lib/arm/asm/mmu-api.h > @@ -22,5 +22,6 @@ extern void mmu_set_range_sect(pgd_t *pgtable, uintptr_t virt_offset, > extern void mmu_set_range_ptes(pgd_t *pgtable, uintptr_t virt_offset, > phys_addr_t phys_start, phys_addr_t phys_end, > pgprot_t prot); > +extern pteval_t *mmu_get_pte(pgd_t *pgtable, uintptr_t vaddr); > extern void mmu_clear_user(pgd_t *pgtable, unsigned long vaddr); > #endif > diff --git a/lib/arm/mmu.c b/lib/arm/mmu.c > index d937f20..e58da10 100644 > --- a/lib/arm/mmu.c > +++ b/lib/arm/mmu.c > @@ -212,15 +212,21 @@ unsigned long __phys_to_virt(phys_addr_t addr) > return addr; > } > > -void mmu_clear_user(pgd_t *pgtable, unsigned long vaddr) > +pteval_t *mmu_get_pte(pgd_t *pgtable, uintptr_t vaddr) > { > + /* > + * NOTE: The Arm architecture requires the use of a > + * break-before-make sequence before making any changes to > + * PTEs (Arm ARM D5-2669 for AArch64, B3-1378 for AArch32). > + */ That should go above the function definition. Also, break-before-make is not required for every PTE change, only when certain conditions are met. Thanks, Alex
diff --git a/lib/arm/asm/mmu-api.h b/lib/arm/asm/mmu-api.h index 2bbe1fa..3d04d03 100644 --- a/lib/arm/asm/mmu-api.h +++ b/lib/arm/asm/mmu-api.h @@ -22,5 +22,6 @@ extern void mmu_set_range_sect(pgd_t *pgtable, uintptr_t virt_offset, extern void mmu_set_range_ptes(pgd_t *pgtable, uintptr_t virt_offset, phys_addr_t phys_start, phys_addr_t phys_end, pgprot_t prot); +extern pteval_t *mmu_get_pte(pgd_t *pgtable, uintptr_t vaddr); extern void mmu_clear_user(pgd_t *pgtable, unsigned long vaddr); #endif diff --git a/lib/arm/mmu.c b/lib/arm/mmu.c index d937f20..e58da10 100644 --- a/lib/arm/mmu.c +++ b/lib/arm/mmu.c @@ -212,15 +212,21 @@ unsigned long __phys_to_virt(phys_addr_t addr) return addr; } -void mmu_clear_user(pgd_t *pgtable, unsigned long vaddr) +pteval_t *mmu_get_pte(pgd_t *pgtable, uintptr_t vaddr) { + /* + * NOTE: The Arm architecture requires the use of a + * break-before-make sequence before making any changes to + * PTEs (Arm ARM D5-2669 for AArch64, B3-1378 for AArch32). + */ + pgd_t *pgd; pud_t *pud; pmd_t *pmd; pte_t *pte; if (!mmu_enabled()) - return; + return NULL; pgd = pgd_offset(pgtable, vaddr); assert(pgd_valid(*pgd)); @@ -229,17 +235,21 @@ void mmu_clear_user(pgd_t *pgtable, unsigned long vaddr) pmd = pmd_offset(pud, vaddr); assert(pmd_valid(*pmd)); - if (pmd_huge(*pmd)) { - pmd_t entry = __pmd(pmd_val(*pmd) & ~PMD_SECT_USER); - WRITE_ONCE(*pmd, entry); - goto out_flush_tlb; - } + if (pmd_huge(*pmd)) + return &pmd_val(*pmd); pte = pte_offset(pmd, vaddr); assert(pte_valid(*pte)); - pte_t entry = __pte(pte_val(*pte) & ~PTE_USER); - WRITE_ONCE(*pte, entry); -out_flush_tlb: - flush_tlb_page(vaddr); + return &pte_val(*pte); +} + +void mmu_clear_user(pgd_t *pgtable, unsigned long vaddr) +{ + pteval_t *p_pte = mmu_get_pte(pgtable, vaddr); + if (p_pte) { + pteval_t entry = *p_pte & ~PTE_USER; + WRITE_ONCE(*p_pte, entry); + flush_tlb_page(vaddr); + } }