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-rw-r--r--arch/powerpc/mm/Makefile1
-rw-r--r--arch/powerpc/mm/hash_low_64.S16
-rw-r--r--arch/powerpc/mm/hash_utils_64.c83
-rw-r--r--arch/powerpc/mm/subpage-prot.c213
4 files changed, 295 insertions, 18 deletions
diff --git a/arch/powerpc/mm/Makefile b/arch/powerpc/mm/Makefile
index 20629ae95c5..41649a5d360 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 e935edd6b72..21d24848647 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 9326a6962b4..7b4cacb0d4b 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 00000000000..4cafc0c33d0
--- /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;
+}
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2024-12-28 09:12:21 +0000