diff options
Diffstat (limited to 'src/kernel/arch')
| -rw-r--r-- | src/kernel/arch/generic.h | 4 | ||||
| -rw-r--r-- | src/kernel/arch/i386/pagedir.c | 27 |
2 files changed, 31 insertions, 0 deletions
diff --git a/src/kernel/arch/generic.h b/src/kernel/arch/generic.h index 0b005a2..6200320 100644 --- a/src/kernel/arch/generic.h +++ b/src/kernel/arch/generic.h @@ -24,3 +24,7 @@ struct pagedir *pagedir_new(); void pagedir_map(struct pagedir *dir, void *virt, void *phys, bool user, bool writeable); void pagedir_switch(struct pagedir *); + +// return 0 on failure +void *pagedir_virt2phys(struct pagedir *dir, const void *virt, + bool user, bool writeable); diff --git a/src/kernel/arch/i386/pagedir.c b/src/kernel/arch/i386/pagedir.c index 8ab406d..02361e6 100644 --- a/src/kernel/arch/i386/pagedir.c +++ b/src/kernel/arch/i386/pagedir.c @@ -91,3 +91,30 @@ void pagedir_map(struct pagedir *dir, void *virt, void *phys, void pagedir_switch(struct pagedir *dir) { asm volatile("mov %0, %%cr3;" : : "r" (dir) : "memory"); } + +void *pagedir_virt2phys(struct pagedir *dir, const void *virt, + bool user, bool writeable) +{ + uintptr_t virt_casted = (uintptr_t) virt; + uintptr_t phys; + uint32_t pd_idx = virt_casted >> 22; + uint32_t pt_idx = virt_casted >> 12 & 0x03FF; + struct pagetable_entry *pagetable, page; + + /* DOESN'T CHECK PERMISSIONS ON PAGE DIRS, TODO + * while i don't currently see a reason to set permissions + * directly on page dirs, i might see one in the future. + * leaving this as-is would be a security bug */ + if (!dir->e[pd_idx].present) return 0; + + pagetable = (void*)(dir->e[pd_idx].address << 11); + page = pagetable[pt_idx]; + + if (!page.present) return 0; + if (user && !page.user) return 0; + if (writeable && !page.writeable) return 0; + + phys = page.address << 11; + phys |= (uintptr_t)virt & 0xFFF; + return (void*)phys; +} |