From ea6fb41752dda2e450bd8a318c7400f8cfa9111e Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 23 Feb 2012 01:33:19 -0500 Subject: um: embed ->stub_pages[] into mmu_context seriously, kmalloc() for two-element array of pointers? Signed-off-by: Al Viro --- arch/um/kernel/skas/mmu.c | 23 +++++------------------ 1 file changed, 5 insertions(+), 18 deletions(-) (limited to 'arch/um/kernel/skas/mmu.c') diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c index 1aee587e9c5d..db2ef422c1b8 100644 --- a/arch/um/kernel/skas/mmu.c +++ b/arch/um/kernel/skas/mmu.c @@ -92,8 +92,6 @@ int init_new_context(struct task_struct *task, struct mm_struct *mm) goto out_free; } - to_mm->stub_pages = NULL; - return 0; out_free: @@ -120,29 +118,20 @@ void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) 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); - mm->context.stub_pages = pages; + mm->context.stub_pages[0] = virt_to_page(&__syscall_stub_start); + mm->context.stub_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); + VM_MAYEXEC | VM_DONTCOPY, + mm->context.stub_pages); if (err) { printk(KERN_ERR "install_special_mapping returned %d\n", err); - goto out_free; + goto out; } return; -out_free: - kfree(pages); out: force_sigsegv(SIGSEGV, current); } @@ -151,8 +140,6 @@ void arch_exit_mmap(struct mm_struct *mm) { pte_t *pte; - if (mm->context.stub_pages != NULL) - kfree(mm->context.stub_pages); pte = virt_to_pte(mm, STUB_CODE); if (pte != NULL) pte_clear(mm, STUB_CODE, pte); -- cgit v1.2.3 From ac2aca2817ca10ad30f86d0d3caa41ea8cc4f0f0 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 23 Feb 2012 01:37:19 -0500 Subject: um: uml_dup_mmap() relies on ->mmap_sem being held, but activate_mm() doesn't hold it ... while calling uml_dup_mmap() Signed-off-by: Al Viro --- arch/um/include/asm/mmu_context.h | 11 +++++++++-- arch/um/kernel/skas/mmu.c | 2 +- 2 files changed, 10 insertions(+), 3 deletions(-) (limited to 'arch/um/kernel/skas/mmu.c') diff --git a/arch/um/include/asm/mmu_context.h b/arch/um/include/asm/mmu_context.h index 591b3d8d7614..aa4a743dc4ab 100644 --- a/arch/um/include/asm/mmu_context.h +++ b/arch/um/include/asm/mmu_context.h @@ -9,7 +9,7 @@ #include #include -extern void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm); +extern void uml_setup_stubs(struct mm_struct *mm); extern void arch_exit_mmap(struct mm_struct *mm); #define deactivate_mm(tsk,mm) do { } while (0) @@ -23,7 +23,9 @@ static inline void activate_mm(struct mm_struct *old, struct mm_struct *new) * when the new ->mm is used for the first time. */ __switch_mm(&new->context.id); - arch_dup_mmap(old, new); + down_write(&new->mmap_sem); + uml_setup_stubs(new); + up_write(&new->mmap_sem); } static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, @@ -39,6 +41,11 @@ static inline void switch_mm(struct mm_struct *prev, struct mm_struct *next, } } +static inline void arch_dup_mmap(struct mm_struct *oldmm, struct mm_struct *mm) +{ + uml_setup_stubs(mm); +} + static inline void enter_lazy_tlb(struct mm_struct *mm, struct task_struct *tsk) { diff --git a/arch/um/kernel/skas/mmu.c b/arch/um/kernel/skas/mmu.c index db2ef422c1b8..4947b319f53a 100644 --- a/arch/um/kernel/skas/mmu.c +++ b/arch/um/kernel/skas/mmu.c @@ -101,7 +101,7 @@ 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) +void uml_setup_stubs(struct mm_struct *mm) { struct page **pages; int err, ret; -- cgit v1.2.3