On Mon, Apr 01, 2019 at 12:20:22PM +0100, Vincenzo Frascino wrote:
> diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
> index 2d419006ad43..9556ad2036ef 100644
> --- a/arch/arm64/kernel/vdso.c
> +++ b/arch/arm64/kernel/vdso.c
> @@ -1,5 +1,7 @@
> /*
> - * VDSO implementation for AArch64 and vector page setup for AArch32.
> + * VDSO implementation for AArch64 and for AArch32:
> + * AArch64: vDSO implementation contains pages setup and data page update.
> + * AArch32: vDSO implementation contains sigreturn and kuser pages setup.
> *
> * Copyright (C) 2012 ARM Limited
> *
> @@ -53,61 +55,117 @@ struct vdso_data *vdso_data = &vdso_data_store.data;
> /*
> * Create and map the vectors page for AArch32 tasks.
> */
> -static struct page *vectors_page[1] __ro_after_init;
> +/*
> + * aarch32_vdso_pages:
> + * 0 - kuser helpers
> + * 1 - sigreturn code
> + */
> +static struct page *aarch32_vdso_pages[2] __ro_after_init;
More of a nitpick, the code may be easier to follow if we had two
separate variables. Does the array buy us anything?
> +static const struct vm_special_mapping aarch32_vdso_spec[2] = {
> + {
> + /* Must be named [vectors] for compatibility with arm. */
> + .name = "[vectors]",
> + .pages = &aarch32_vdso_pages[0],
> + },
> + {
> + /* Must be named [sigpage] for compatibility with arm. */
> + .name = "[sigpage]",
> + .pages = &aarch32_vdso_pages[1],
> + },
> +};
[...]
> -int aarch32_setup_vectors_page(struct linux_binprm *bprm, int uses_interp)
> +static int aarch32_kuser_helpers_setup(struct mm_struct *mm)
> {
> - struct mm_struct *mm = current->mm;
> - unsigned long addr = AARCH32_VECTORS_BASE;
> - static const struct vm_special_mapping spec = {
> - .name = "[vectors]",
> - .pages = vectors_page,
> + void *ret;
> +
> + /* The kuser helpers must be mapped at the ABI-defined high address */
> + ret = _install_special_mapping(mm, AARCH32_KUSER_BASE, PAGE_SIZE,
> + VM_READ | VM_EXEC |
> + VM_MAYREAD | VM_MAYEXEC,
> + &aarch32_vdso_spec[0]);
> +
> + return PTR_ERR_OR_ZERO(ret);
> +}
>
> - };
> +static int aarch32_sigreturn_setup(struct mm_struct *mm)
> +{
> + unsigned long addr;
> void *ret;
>
> - if (down_write_killable(&mm->mmap_sem))
> - return -EINTR;
> - current->mm->context.vdso = (void *)addr;
> + addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0);
> + if (IS_ERR_VALUE(addr)) {
> + ret = ERR_PTR(addr);
> + goto out;
> + }
>
> - /* Map vectors page at the high address. */
> ret = _install_special_mapping(mm, addr, PAGE_SIZE,
> - VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC,
> - &spec);
> + VM_READ | VM_EXEC | VM_MAYREAD |
> + VM_MAYWRITE | VM_MAYEXEC,
> + &aarch32_vdso_spec[1]);
Any reason for setting VM_MAYWRITE here?
--
Catalin
