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-rw-r--r--arch/um/include/as-layout.h19
-rw-r--r--arch/um/include/common-offsets.h3
-rw-r--r--arch/um/kernel/exec.c5
-rw-r--r--arch/um/kernel/skas/mmu.c104
-rw-r--r--arch/um/kernel/tlb.c11
-rw-r--r--include/asm-um/mmu_context.h7
6 files changed, 75 insertions, 74 deletions
diff --git a/arch/um/include/as-layout.h b/arch/um/include/as-layout.h
index a2008f550fee..606bb5c7fdf6 100644
--- a/arch/um/include/as-layout.h
+++ b/arch/um/include/as-layout.h
@@ -29,21 +29,10 @@
#define _AC(X, Y) __AC(X, Y)
#endif
-/*
- * The "- 1"'s are to avoid gcc complaining about integer overflows
- * and unrepresentable decimal constants. With 3-level page tables,
- * TASK_SIZE is 0x80000000, which gets turned into its signed decimal
- * equivalent in asm-offsets.s. gcc then complains about that being
- * unsigned only in C90. To avoid that, UM_TASK_SIZE is defined as
- * TASK_SIZE - 1. To compensate, we need to add the 1 back here.
- * However, adding it back to UM_TASK_SIZE produces more gcc
- * complaints. So, I adjust the thing being subtracted from
- * UM_TASK_SIZE instead. Bah.
- */
-#define STUB_CODE _AC((unsigned long), \
- UM_TASK_SIZE - (2 * UM_KERN_PAGE_SIZE - 1))
-#define STUB_DATA _AC((unsigned long), UM_TASK_SIZE - (UM_KERN_PAGE_SIZE - 1))
-#define STUB_START _AC(, STUB_CODE)
+#define STUB_START _AC(, 0x100000)
+#define STUB_CODE _AC((unsigned long), STUB_START)
+#define STUB_DATA _AC((unsigned long), STUB_CODE + UM_KERN_PAGE_SIZE)
+#define STUB_END _AC((unsigned long), STUB_DATA + UM_KERN_PAGE_SIZE)
#ifndef __ASSEMBLY__
diff --git a/arch/um/include/common-offsets.h b/arch/um/include/common-offsets.h
index 5b67d7ced2a7..b54bd35585c2 100644
--- a/arch/um/include/common-offsets.h
+++ b/arch/um/include/common-offsets.h
@@ -39,6 +39,3 @@ DEFINE(UM_HZ, HZ);
DEFINE(UM_USEC_PER_SEC, USEC_PER_SEC);
DEFINE(UM_NSEC_PER_SEC, NSEC_PER_SEC);
DEFINE(UM_NSEC_PER_USEC, NSEC_PER_USEC);
-
-/* See as-layout.h for an explanation of the "- 1". Bah. */
-DEFINE(UM_TASK_SIZE, TASK_SIZE - 1);
diff --git a/arch/um/kernel/exec.c b/arch/um/kernel/exec.c
index bf66b5b7bc68..76a62c0cb2bc 100644
--- a/arch/um/kernel/exec.c
+++ b/arch/um/kernel/exec.c
@@ -19,12 +19,13 @@
void flush_thread(void)
{
void *data = NULL;
- unsigned long end = proc_mm ? TASK_SIZE : STUB_START;
int ret;
arch_flush_thread(&current->thread.arch);
- ret = unmap(&current->mm->context.id, 0, end, 1, &data);
+ ret = unmap(&current->mm->context.id, 0, STUB_START, 0, &data);
+ ret = ret || unmap(&current->mm->context.id, STUB_END,
+ TASK_SIZE - STUB_END, 1, &data);
if (ret) {
printk(KERN_ERR "flush_thread - clearing address space failed, "
"err = %d\n", ret);
diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c
index 6da9ab4f5a18..e8dc8540d444 100644
--- a/arch/um/kernel/skas/mmu.c
+++ b/arch/um/kernel/skas/mmu.c
@@ -34,25 +34,6 @@ static int init_stub_pte(struct mm_struct *mm, unsigned long proc,
if (!pte)
goto out_pte;
- /*
- * There's an interaction between the skas0 stub pages, stack
- * randomization, and the BUG at the end of exit_mmap. exit_mmap
- * checks that the number of page tables freed is the same as had
- * been allocated. If the stack is on the last page table page,
- * then the stack pte page will be freed, and if not, it won't. To
- * avoid having to know where the stack is, or if the process mapped
- * something at the top of its address space for some other reason,
- * we set TASK_SIZE to end at the start of the last page table.
- * This keeps exit_mmap off the last page, but introduces a leak
- * of that page. So, we hang onto it here and free it in
- * destroy_context_skas.
- */
-
- mm->context.last_page_table = pmd_page_vaddr(*pmd);
-#ifdef CONFIG_3_LEVEL_PGTABLES
- mm->context.last_pmd = (unsigned long) __va(pud_val(*pud));
-#endif
-
*pte = mk_pte(virt_to_page(kernel), __pgprot(_PAGE_PRESENT));
*pte = pte_mkread(*pte);
return 0;
@@ -76,24 +57,6 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
stack = get_zeroed_page(GFP_KERNEL);
if (stack == 0)
goto out;
-
- /*
- * This zeros the entry that pgd_alloc didn't, needed since
- * we are about to reinitialize it, and want mm.nr_ptes to
- * be accurate.
- */
- mm->pgd[USER_PTRS_PER_PGD] = __pgd(0);
-
- ret = init_stub_pte(mm, STUB_CODE,
- (unsigned long) &__syscall_stub_start);
- if (ret)
- goto out_free;
-
- ret = init_stub_pte(mm, STUB_DATA, stack);
- if (ret)
- goto out_free;
-
- mm->nr_ptes--;
}
to_mm->id.stack = stack;
@@ -137,6 +100,64 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm)
return ret;
}
+void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm)
+{
+ struct page **pages;
+ int err, ret;
+
+ if (!skas_needs_stub)
+ return;
+
+ ret = init_stub_pte(mm, STUB_CODE,
+ (unsigned long) &__syscall_stub_start);
+ if (ret)
+ goto out;
+
+ ret = init_stub_pte(mm, STUB_DATA, mm->context.id.stack);
+ if (ret)
+ goto out;
+
+ pages = kmalloc(2 * sizeof(struct page *), GFP_KERNEL);
+ if (pages == NULL) {
+ printk(KERN_ERR "arch_dup_mmap failed to allocate 2 page "
+ "pointers\n");
+ goto out;
+ }
+
+ pages[0] = virt_to_page(&__syscall_stub_start);
+ pages[1] = virt_to_page(mm->context.id.stack);
+
+ /* dup_mmap already holds mmap_sem */
+ err = install_special_mapping(mm, STUB_START, STUB_END - STUB_START,
+ VM_READ | VM_MAYREAD | VM_EXEC |
+ VM_MAYEXEC | VM_DONTCOPY, pages);
+ if (err) {
+ printk(KERN_ERR "install_special_mapping returned %d\n", err);
+ goto out_free;
+ }
+ return;
+
+out_free:
+ kfree(pages);
+out:
+ force_sigsegv(SIGSEGV, current);
+}
+
+void arch_exit_mmap(struct mm_struct *mm)
+{
+ pte_t *pte;
+
+ pte = virt_to_pte(mm, STUB_CODE);
+ if (pte != NULL)
+ pte_clear(mm, STUB_CODE, pte);
+
+ pte = virt_to_pte(mm, STUB_DATA);
+ if (pte == NULL)
+ return;
+
+ pte_clear(mm, STUB_DATA, pte);
+}
+
void destroy_context(struct mm_struct *mm)
{
struct mm_context *mmu = &mm->context;
@@ -146,15 +167,8 @@ void destroy_context(struct mm_struct *mm)
else
os_kill_ptraced_process(mmu->id.u.pid, 1);
- if (!proc_mm || !ptrace_faultinfo) {
+ if (skas_needs_stub)
free_page(mmu->id.stack);
- pte_lock_deinit(virt_to_page(mmu->last_page_table));
- pte_free_kernel(mm, (pte_t *) mmu->last_page_table);
- dec_zone_page_state(virt_to_page(mmu->last_page_table), NR_PAGETABLE);
-#ifdef CONFIG_3_LEVEL_PGTABLES
- pmd_free(mm, (pmd_t *) mmu->last_pmd);
-#endif
- }
free_ldt(mmu);
}
diff --git a/arch/um/kernel/tlb.c b/arch/um/kernel/tlb.c
index 429fed2f66b2..ef5a2a20d351 100644
--- a/arch/um/kernel/tlb.c
+++ b/arch/um/kernel/tlb.c
@@ -184,6 +184,9 @@ static inline int update_pte_range(pmd_t *pmd, unsigned long addr,
pte = pte_offset_kernel(pmd, addr);
do {
+ if ((addr >= STUB_START) && (addr < STUB_END))
+ continue;
+
r = pte_read(*pte);
w = pte_write(*pte);
x = pte_exec(*pte);
@@ -486,9 +489,6 @@ void __flush_tlb_one(unsigned long addr)
static void fix_range(struct mm_struct *mm, unsigned long start_addr,
unsigned long end_addr, int force)
{
- if (!proc_mm && (end_addr > STUB_START))
- end_addr = STUB_START;
-
fix_range_common(mm, start_addr, end_addr, force);
}
@@ -502,8 +502,6 @@ void flush_tlb_range(struct vm_area_struct *vma, unsigned long start,
void flush_tlb_mm(struct mm_struct *mm)
{
- unsigned long end;
-
/*
* Don't bother flushing if this address space is about to be
* destroyed.
@@ -511,8 +509,7 @@ void flush_tlb_mm(struct mm_struct *mm)
if (atomic_read(&mm->mm_users) == 0)
return;
- end = proc_mm ? TASK_SIZE : STUB_START;
- fix_range(mm, 0, end, 0);
+ fix_range(mm, 0, TASK_SIZE, 0);
}
void force_flush_all(void)
diff --git a/include/asm-um/mmu_context.h b/include/asm-um/mmu_context.h
index 5f3b863aef9a..6686fc524ca1 100644
--- a/include/asm-um/mmu_context.h
+++ b/include/asm-um/mmu_context.h
@@ -6,11 +6,12 @@
#ifndef __UM_MMU_CONTEXT_H
#define __UM_MMU_CONTEXT_H
-#include <asm-generic/mm_hooks.h>
-
#include "linux/sched.h"
#include "um_mmu.h"
+extern void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm);
+extern void arch_exit_mmap(struct mm_struct *mm);
+
#define get_mmu_context(task) do ; while(0)
#define activate_context(tsk) do ; while(0)
@@ -30,6 +31,8 @@ static inline void activate_mm(struct mm_struct *old, struct mm_struct *new)
*/
if (old != new && (current->flags & PF_BORROWED_MM))
__switch_mm(&new->context.id);
+
+ arch_dup_mmap(old, new);
}
static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next,
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-16 10:49:25 +0000