From: Vasily Gorbik gor@linux.ibm.com
[ Upstream commit d1befa65823e9c6d013883b8a41d081ec338c489 ]
vdso_fault used is_compat_task function (on s390 it tests "current" thread_info flags) to distinguish compat tasks and map 31-bit vdso pages. But "current" task might not correspond to mm context.
When 31-bit compat inferior is executed under gdb, gdb does PTRACE_PEEKTEXT on vdso page, causing vdso_fault with "current" being 64-bit gdb process. So, 31-bit inferior ends up with 64-bit vdso mapped.
To avoid this problem a new compat_mm flag has been introduced into mm context. This flag is used in vdso_fault and vdso_mremap instead of is_compat_task.
Signed-off-by: Vasily Gorbik gor@linux.ibm.com Signed-off-by: Martin Schwidefsky schwidefsky@de.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/include/asm/mmu.h | 2 ++ arch/s390/include/asm/mmu_context.h | 1 + arch/s390/kernel/vdso.c | 8 +++++--- 3 files changed, 8 insertions(+), 3 deletions(-)
diff --git a/arch/s390/include/asm/mmu.h b/arch/s390/include/asm/mmu.h index a8418e1379eb7..bcfb6371086f2 100644 --- a/arch/s390/include/asm/mmu.h +++ b/arch/s390/include/asm/mmu.h @@ -32,6 +32,8 @@ typedef struct { unsigned int uses_cmm:1; /* The gmaps associated with this context are allowed to use huge pages. */ unsigned int allow_gmap_hpage_1m:1; + /* The mmu context is for compat task */ + unsigned int compat_mm:1; } mm_context_t;
#define INIT_MM_CONTEXT(name) \ diff --git a/arch/s390/include/asm/mmu_context.h b/arch/s390/include/asm/mmu_context.h index 09b61d0e491f6..e4462202200d7 100644 --- a/arch/s390/include/asm/mmu_context.h +++ b/arch/s390/include/asm/mmu_context.h @@ -25,6 +25,7 @@ static inline int init_new_context(struct task_struct *tsk, atomic_set(&mm->context.flush_count, 0); mm->context.gmap_asce = 0; mm->context.flush_mm = 0; + mm->context.compat_mm = 0; #ifdef CONFIG_PGSTE mm->context.alloc_pgste = page_table_allocate_pgste || test_thread_flag(TIF_PGSTE) || diff --git a/arch/s390/kernel/vdso.c b/arch/s390/kernel/vdso.c index 3031cc6dd0ab4..ec31b48a42a52 100644 --- a/arch/s390/kernel/vdso.c +++ b/arch/s390/kernel/vdso.c @@ -56,7 +56,7 @@ static vm_fault_t vdso_fault(const struct vm_special_mapping *sm, vdso_pagelist = vdso64_pagelist; vdso_pages = vdso64_pages; #ifdef CONFIG_COMPAT - if (is_compat_task()) { + if (vma->vm_mm->context.compat_mm) { vdso_pagelist = vdso32_pagelist; vdso_pages = vdso32_pages; } @@ -77,7 +77,7 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
vdso_pages = vdso64_pages; #ifdef CONFIG_COMPAT - if (is_compat_task()) + if (vma->vm_mm->context.compat_mm) vdso_pages = vdso32_pages; #endif
@@ -224,8 +224,10 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
vdso_pages = vdso64_pages; #ifdef CONFIG_COMPAT - if (is_compat_task()) + if (is_compat_task()) { vdso_pages = vdso32_pages; + mm->context.compat_mm = 1; + } #endif /* * vDSO has a problem and was disabled, just don't "enable" it for