diff options
Diffstat (limited to 'arch/powerpc')
| -rw-r--r-- | arch/powerpc/Kconfig | 8 | ||||
| -rw-r--r-- | arch/powerpc/kernel/head_64.S | 1 | ||||
| -rw-r--r-- | arch/powerpc/mm/Makefile | 1 | ||||
| -rw-r--r-- | arch/powerpc/mm/hash_low_64.S | 16 | ||||
| -rw-r--r-- | arch/powerpc/mm/hash_utils_64.c | 83 | ||||
| -rw-r--r-- | arch/powerpc/mm/subpage-prot.c | 213 |
6 files changed, 304 insertions, 18 deletions
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig index 66a3d8cee5cf..53d0955abf11 100644 --- a/arch/powerpc/Kconfig +++ b/arch/powerpc/Kconfig @@ -342,6 +342,14 @@ config PPC_64K_PAGES while on hardware with such support, it will be used to map normal application pages. +config PPC_SUBPAGE_PROT + bool "Support setting protections for 4k subpages" + depends on PPC_64K_PAGES + help + This option adds support for a system call to allow user programs + to set access permissions (read/write, readonly, or no access) + on the 4k subpages of each 64k page. + config SCHED_SMT bool "SMT (Hyperthreading) scheduler support" depends on PPC64 && SMP diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index c34986835a4e..11b4f6d9ffce 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -903,6 +903,7 @@ handle_page_fault: * the PTE insertion */ 12: bl .save_nvgprs + mr r5,r3 addi r3,r1,STACK_FRAME_OVERHEAD ld r4,_DAR(r1) bl .low_hash_fault diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile index 20629ae95c50..41649a5d3602 100644 --- a/arch/powerpc/mm/Makefile +++ b/arch/powerpc/mm/Makefile @@ -22,3 +22,4 @@ obj-$(CONFIG_FSL_BOOKE) += fsl_booke_mmu.o obj-$(CONFIG_NEED_MULTIPLE_NODES) += numa.o obj-$(CONFIG_PPC_MM_SLICES) += slice.o obj-$(CONFIG_HUGETLB_PAGE) += hugetlbpage.o +obj-$(CONFIG_PPC_SUBPAGE_PROT) += subpage-prot.o diff --git a/arch/powerpc/mm/hash_low_64.S b/arch/powerpc/mm/hash_low_64.S index e935edd6b72b..21d248486479 100644 --- a/arch/powerpc/mm/hash_low_64.S +++ b/arch/powerpc/mm/hash_low_64.S @@ -331,7 +331,8 @@ htab_pte_insert_failure: *****************************************************************************/ /* _hash_page_4K(unsigned long ea, unsigned long access, unsigned long vsid, - * pte_t *ptep, unsigned long trap, int local, int ssize) + * pte_t *ptep, unsigned long trap, int local, int ssize, + * int subpg_prot) */ /* @@ -429,12 +430,19 @@ END_FTR_SECTION_IFSET(CPU_FTR_1T_SEGMENT) xor r28,r28,r0 /* hash */ /* Convert linux PTE bits into HW equivalents */ -4: andi. r3,r30,0x1fe /* Get basic set of flags */ - xori r3,r3,HPTE_R_N /* _PAGE_EXEC -> NOEXEC */ +4: +#ifdef CONFIG_PPC_SUBPAGE_PROT + andc r10,r30,r10 + andi. r3,r10,0x1fe /* Get basic set of flags */ + rlwinm r0,r10,32-9+1,30,30 /* _PAGE_RW -> _PAGE_USER (r0) */ +#else + andi. r3,r30,0x1fe /* Get basic set of flags */ rlwinm r0,r30,32-9+1,30,30 /* _PAGE_RW -> _PAGE_USER (r0) */ +#endif + xori r3,r3,HPTE_R_N /* _PAGE_EXEC -> NOEXEC */ rlwinm r4,r30,32-7+1,30,30 /* _PAGE_DIRTY -> _PAGE_USER (r4) */ and r0,r0,r4 /* _PAGE_RW & _PAGE_DIRTY ->r0 bit 30*/ - andc r0,r30,r0 /* r0 = pte & ~r0 */ + andc r0,r3,r0 /* r0 = pte & ~r0 */ rlwimi r3,r0,32-1,31,31 /* Insert result into PP lsb */ ori r3,r3,HPTE_R_C /* Always add "C" bit for perf. */ diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c index 9326a6962b42..7b4cacb0d4ba 100644 --- a/arch/powerpc/mm/hash_utils_64.c +++ b/arch/powerpc/mm/hash_utils_64.c @@ -637,7 +637,7 @@ unsigned int hash_page_do_lazy_icache(unsigned int pp, pte_t pte, int trap) * For now this makes the whole process use 4k pages. */ #ifdef CONFIG_PPC_64K_PAGES -static void demote_segment_4k(struct mm_struct *mm, unsigned long addr) +void demote_segment_4k(struct mm_struct *mm, unsigned long addr) { if (mm->context.user_psize == MMU_PAGE_4K) return; @@ -645,13 +645,62 @@ static void demote_segment_4k(struct mm_struct *mm, unsigned long addr) #ifdef CONFIG_SPU_BASE spu_flush_all_slbs(mm); #endif + if (get_paca()->context.user_psize != MMU_PAGE_4K) { + get_paca()->context = mm->context; + slb_flush_and_rebolt(); + } } #endif /* CONFIG_PPC_64K_PAGES */ +#ifdef CONFIG_PPC_SUBPAGE_PROT +/* + * This looks up a 2-bit protection code for a 4k subpage of a 64k page. + * Userspace sets the subpage permissions using the subpage_prot system call. + * + * Result is 0: full permissions, _PAGE_RW: read-only, + * _PAGE_USER or _PAGE_USER|_PAGE_RW: no access. + */ +static int subpage_protection(pgd_t *pgdir, unsigned long ea) +{ + struct subpage_prot_table *spt = pgd_subpage_prot(pgdir); + u32 spp = 0; + u32 **sbpm, *sbpp; + + if (ea >= spt->maxaddr) + return 0; + if (ea < 0x100000000) { + /* addresses below 4GB use spt->low_prot */ + sbpm = spt->low_prot; + } else { + sbpm = spt->protptrs[ea >> SBP_L3_SHIFT]; + if (!sbpm) + return 0; + } + sbpp = sbpm[(ea >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1)]; + if (!sbpp) + return 0; + spp = sbpp[(ea >> PAGE_SHIFT) & (SBP_L1_COUNT - 1)]; + + /* extract 2-bit bitfield for this 4k subpage */ + spp >>= 30 - 2 * ((ea >> 12) & 0xf); + + /* turn 0,1,2,3 into combination of _PAGE_USER and _PAGE_RW */ + spp = ((spp & 2) ? _PAGE_USER : 0) | ((spp & 1) ? _PAGE_RW : 0); + return spp; +} + +#else /* CONFIG_PPC_SUBPAGE_PROT */ +static inline int subpage_protection(pgd_t *pgdir, unsigned long ea) +{ + return 0; +} +#endif + /* Result code is: * 0 - handled * 1 - normal page fault * -1 - critical hash insertion error + * -2 - access not permitted by subpage protection mechanism */ int hash_page(unsigned long ea, unsigned long access, unsigned long trap) { @@ -802,7 +851,14 @@ int hash_page(unsigned long ea, unsigned long access, unsigned long trap) rc = __hash_page_64K(ea, access, vsid, ptep, trap, local, ssize); else #endif /* CONFIG_PPC_HAS_HASH_64K */ - rc = __hash_page_4K(ea, access, vsid, ptep, trap, local, ssize); + { + int spp = subpage_protection(pgdir, ea); + if (access & spp) + rc = -2; + else + rc = __hash_page_4K(ea, access, vsid, ptep, trap, + local, ssize, spp); + } #ifndef CONFIG_PPC_64K_PAGES DBG_LOW(" o-pte: %016lx\n", pte_val(*ptep)); @@ -874,7 +930,8 @@ void hash_preload(struct mm_struct *mm, unsigned long ea, __hash_page_64K(ea, access, vsid, ptep, trap, local, ssize); else #endif /* CONFIG_PPC_HAS_HASH_64K */ - __hash_page_4K(ea, access, vsid, ptep, trap, local, ssize); + __hash_page_4K(ea, access, vsid, ptep, trap, local, ssize, + subpage_protection(pgdir, ea)); local_irq_restore(flags); } @@ -919,19 +976,17 @@ void flush_hash_range(unsigned long number, int local) * low_hash_fault is called when we the low level hash code failed * to instert a PTE due to an hypervisor error */ -void low_hash_fault(struct pt_regs *regs, unsigned long address) +void low_hash_fault(struct pt_regs *regs, unsigned long address, int rc) { if (user_mode(regs)) { - siginfo_t info; - - info.si_signo = SIGBUS; - info.si_errno = 0; - info.si_code = BUS_ADRERR; - info.si_addr = (void __user *)address; - force_sig_info(SIGBUS, &info, current); - return; - } - bad_page_fault(regs, address, SIGBUS); +#ifdef CONFIG_PPC_SUBPAGE_PROT + if (rc == -2) + _exception(SIGSEGV, regs, SEGV_ACCERR, address); + else +#endif + _exception(SIGBUS, regs, BUS_ADRERR, address); + } else + bad_page_fault(regs, address, SIGBUS); } #ifdef CONFIG_DEBUG_PAGEALLOC diff --git a/arch/powerpc/mm/subpage-prot.c b/arch/powerpc/mm/subpage-prot.c new file mode 100644 index 000000000000..4cafc0c33d0a --- /dev/null +++ b/arch/powerpc/mm/subpage-prot.c @@ -0,0 +1,213 @@ +/* + * Copyright 2007-2008 Paul Mackerras, IBM Corp. + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/errno.h> +#include <linux/kernel.h> +#include <linux/gfp.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <linux/mm.h> +#include <linux/hugetlb.h> + +#include <asm/pgtable.h> +#include <asm/uaccess.h> +#include <asm/tlbflush.h> + +/* + * Free all pages allocated for subpage protection maps and pointers. + * Also makes sure that the subpage_prot_table structure is + * reinitialized for the next user. + */ +void subpage_prot_free(pgd_t *pgd) +{ + struct subpage_prot_table *spt = pgd_subpage_prot(pgd); + unsigned long i, j, addr; + u32 **p; + + for (i = 0; i < 4; ++i) { + if (spt->low_prot[i]) { + free_page((unsigned long)spt->low_prot[i]); + spt->low_prot[i] = NULL; + } + } + addr = 0; + for (i = 0; i < 2; ++i) { + p = spt->protptrs[i]; + if (!p) + continue; + spt->protptrs[i] = NULL; + for (j = 0; j < SBP_L2_COUNT && addr < spt->maxaddr; + ++j, addr += PAGE_SIZE) + if (p[j]) + free_page((unsigned long)p[j]); + free_page((unsigned long)p); + } + spt->maxaddr = 0; +} + +static void hpte_flush_range(struct mm_struct *mm, unsigned long addr, + int npages) +{ + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + pte_t *pte; + spinlock_t *ptl; + + pgd = pgd_offset(mm, addr); + if (pgd_none(*pgd)) + return; + pud = pud_offset(pgd, addr); + if (pud_none(*pud)) + return; + pmd = pmd_offset(pud, addr); + if (pmd_none(*pmd)) + return; + pte = pte_offset_map_lock(mm, pmd, addr, &ptl); + arch_enter_lazy_mmu_mode(); + for (; npages > 0; --npages) { + pte_update(mm, addr, pte, 0, 0); + addr += PAGE_SIZE; + ++pte; + } + arch_leave_lazy_mmu_mode(); + pte_unmap_unlock(pte - 1, ptl); +} + +/* + * Clear the subpage protection map for an address range, allowing + * all accesses that are allowed by the pte permissions. + */ +static void subpage_prot_clear(unsigned long addr, unsigned long len) +{ + struct mm_struct *mm = current->mm; + struct subpage_prot_table *spt = pgd_subpage_prot(mm->pgd); + u32 **spm, *spp; + int i, nw; + unsigned long next, limit; + + down_write(&mm->mmap_sem); + limit = addr + len; + if (limit > spt->maxaddr) + limit = spt->maxaddr; + for (; addr < limit; addr = next) { + next = pmd_addr_end(addr, limit); + if (addr < 0x100000000) { + spm = spt->low_prot; + } else { + spm = spt->protptrs[addr >> SBP_L3_SHIFT]; + if (!spm) + continue; + } + spp = spm[(addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1)]; + if (!spp) + continue; + spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1); + + i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); + nw = PTRS_PER_PTE - i; + if (addr + (nw << PAGE_SHIFT) > next) + nw = (next - addr) >> PAGE_SHIFT; + + memset(spp, 0, nw * sizeof(u32)); + + /* now flush any existing HPTEs for the range */ + hpte_flush_range(mm, addr, nw); + } + up_write(&mm->mmap_sem); +} + +/* + * Copy in a subpage protection map for an address range. + * The map has 2 bits per 4k subpage, so 32 bits per 64k page. + * Each 2-bit field is 0 to allow any access, 1 to prevent writes, + * 2 or 3 to prevent all accesses. + * Note that the normal page protections also apply; the subpage + * protection mechanism is an additional constraint, so putting 0 + * in a 2-bit field won't allow writes to a page that is otherwise + * write-protected. + */ +long sys_subpage_prot(unsigned long addr, unsigned long len, u32 __user *map) +{ + struct mm_struct *mm = current->mm; + struct subpage_prot_table *spt = pgd_subpage_prot(mm->pgd); + u32 **spm, *spp; + int i, nw; + unsigned long next, limit; + int err; + + /* Check parameters */ + if ((addr & ~PAGE_MASK) || (len & ~PAGE_MASK) || + addr >= TASK_SIZE || len >= TASK_SIZE || addr + len > TASK_SIZE) + return -EINVAL; + + if (is_hugepage_only_range(mm, addr, len)) + return -EINVAL; + + if (!map) { + /* Clear out the protection map for the address range */ + subpage_prot_clear(addr, len); + return 0; + } + + if (!access_ok(VERIFY_READ, map, (len >> PAGE_SHIFT) * sizeof(u32))) + return -EFAULT; + + down_write(&mm->mmap_sem); + for (limit = addr + len; addr < limit; addr = next) { + next = pmd_addr_end(addr, limit); + err = -ENOMEM; + if (addr < 0x100000000) { + spm = spt->low_prot; + } else { + spm = spt->protptrs[addr >> SBP_L3_SHIFT]; + if (!spm) { + spm = (u32 **)get_zeroed_page(GFP_KERNEL); + if (!spm) + goto out; + spt->protptrs[addr >> SBP_L3_SHIFT] = spm; + } + } + spm += (addr >> SBP_L2_SHIFT) & (SBP_L2_COUNT - 1); + spp = *spm; + if (!spp) { + spp = (u32 *)get_zeroed_page(GFP_KERNEL); + if (!spp) + goto out; + *spm = spp; + } + spp += (addr >> PAGE_SHIFT) & (SBP_L1_COUNT - 1); + + local_irq_disable(); + demote_segment_4k(mm, addr); + local_irq_enable(); + + i = (addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1); + nw = PTRS_PER_PTE - i; + if (addr + (nw << PAGE_SHIFT) > next) + nw = (next - addr) >> PAGE_SHIFT; + + up_write(&mm->mmap_sem); + err = -EFAULT; + if (__copy_from_user(spp, map, nw * sizeof(u32))) + goto out2; + map += nw; + down_write(&mm->mmap_sem); + + /* now flush any existing HPTEs for the range */ + hpte_flush_range(mm, addr, nw); + } + if (limit > spt->maxaddr) + spt->maxaddr = limit; + err = 0; + out: + up_write(&mm->mmap_sem); + out2: + return err; +} |