From: Benjamin Herrenschmidt This patch reworks the way the ppc64 is mapped in user memory by the kernel to make it more robust against possible collisions with executable segments. Instead of just whacking a VMA at 1Mb, I now use get_unmapped_area() with a hint, and I moved the mapping of the vDSO to after the mapping of the various ELF segments and of the interpreter, so that conflicts get caught properly (it still has to be before create_elf_tables since the later will fill the AT_SYSINFO_EHDR with the proper address). While I was at it, I also changed the 32 and 64 bits vDSO's to link at their "natural" address of 1Mb instead of 0. This is the address where they are normally mapped in absence of conflict. By doing so, it should be possible to properly prelink one it's been verified to work on glibc. Signed-off-by: Benjamin Herrenschmidt Signed-off-by: Andrew Morton --- 25-akpm/arch/ppc64/kernel/vdso.c | 19 ++++++++++++------- 25-akpm/fs/binfmt_elf.c | 16 ++++++++-------- 25-akpm/include/asm-ppc64/vdso.h | 8 ++++---- 3 files changed, 24 insertions(+), 19 deletions(-) diff -puN arch/ppc64/kernel/vdso.c~ppc64-improve-mapping-of-vdso arch/ppc64/kernel/vdso.c --- 25/arch/ppc64/kernel/vdso.c~ppc64-improve-mapping-of-vdso 2005-04-06 01:41:48.000000000 -0700 +++ 25-akpm/arch/ppc64/kernel/vdso.c 2005-04-06 01:41:48.000000000 -0700 @@ -213,13 +213,14 @@ int arch_setup_additional_pages(struct l vdso_base = VDSO64_MBASE; } + current->thread.vdso_base = 0; + /* vDSO has a problem and was disabled, just don't "enable" it for the * process */ - if (vdso_pages == 0) { - current->thread.vdso_base = 0; + if (vdso_pages == 0) return 0; - } + vma = kmem_cache_alloc(vm_area_cachep, SLAB_KERNEL); if (vma == NULL) return -ENOMEM; @@ -230,12 +231,16 @@ int arch_setup_additional_pages(struct l memset(vma, 0, sizeof(*vma)); /* - * pick a base address for the vDSO in process space. We have a default - * base of 1Mb on which we had a random offset up to 1Mb. - * XXX: Add possibility for a program header to specify that location + * pick a base address for the vDSO in process space. We try to put it + * at vdso_base which is the "natural" base for it, but we might fail + * and end up putting it elsewhere. */ + vdso_base = get_unmapped_area(NULL, vdso_base, + vdso_pages << PAGE_SHIFT, 0, 0); + if (vdso_base & ~PAGE_MASK) + return (int)vdso_base; + current->thread.vdso_base = vdso_base; - /* + ((unsigned long)vma & 0x000ff000); */ vma->vm_mm = mm; vma->vm_start = current->thread.vdso_base; diff -puN fs/binfmt_elf.c~ppc64-improve-mapping-of-vdso fs/binfmt_elf.c --- 25/fs/binfmt_elf.c~ppc64-improve-mapping-of-vdso 2005-04-06 01:41:48.000000000 -0700 +++ 25-akpm/fs/binfmt_elf.c 2005-04-06 01:41:48.000000000 -0700 @@ -782,14 +782,6 @@ static int load_elf_binary(struct linux_ goto out_free_dentry; } -#ifdef ARCH_HAS_SETUP_ADDITIONAL_PAGES - retval = arch_setup_additional_pages(bprm, executable_stack); - if (retval < 0) { - send_sig(SIGKILL, current, 0); - goto out_free_dentry; - } -#endif /* ARCH_HAS_SETUP_ADDITIONAL_PAGES */ - current->mm->start_stack = bprm->p; /* Now we do a little grungy work by mmaping the ELF image into @@ -949,6 +941,14 @@ static int load_elf_binary(struct linux_ set_binfmt(&elf_format); +#ifdef ARCH_HAS_SETUP_ADDITIONAL_PAGES + retval = arch_setup_additional_pages(bprm, executable_stack); + if (retval < 0) { + send_sig(SIGKILL, current, 0); + goto out_free_dentry; + } +#endif /* ARCH_HAS_SETUP_ADDITIONAL_PAGES */ + compute_creds(bprm); current->flags &= ~PF_FORKNOEXEC; create_elf_tables(bprm, &loc->elf_ex, (interpreter_type == INTERPRETER_AOUT), diff -puN include/asm-ppc64/vdso.h~ppc64-improve-mapping-of-vdso include/asm-ppc64/vdso.h --- 25/include/asm-ppc64/vdso.h~ppc64-improve-mapping-of-vdso 2005-04-06 01:41:48.000000000 -0700 +++ 25-akpm/include/asm-ppc64/vdso.h 2005-04-06 01:41:48.000000000 -0700 @@ -4,12 +4,12 @@ #ifdef __KERNEL__ /* Default link addresses for the vDSOs */ -#define VDSO32_LBASE 0 -#define VDSO64_LBASE 0 +#define VDSO32_LBASE 0x100000 +#define VDSO64_LBASE 0x100000 /* Default map addresses */ -#define VDSO32_MBASE 0x100000 -#define VDSO64_MBASE 0x100000 +#define VDSO32_MBASE VDSO32_LBASE +#define VDSO64_MBASE VDSO64_LBASE #define VDSO_VERSION_STRING LINUX_2.6.12 _