On !MMU mode, the address of vdso is accessible from userspace. This commit implements the entry point by pointing a block of page address.
This commit also add memory permission configuration of vdso page to be executable. Signed-off-by: Hajime Tazaki <[email protected]> Signed-off-by: Ricardo Koller <[email protected]> --- arch/x86/um/vdso/vma.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/arch/x86/um/vdso/vma.c b/arch/x86/um/vdso/vma.c index 51a2b9f2eca9..0799b3fe7521 100644 --- a/arch/x86/um/vdso/vma.c +++ b/arch/x86/um/vdso/vma.c @@ -9,6 +9,7 @@ #include <asm/page.h> #include <asm/elf.h> #include <linux/init.h> +#include <os.h> unsigned long um_vdso_addr; static struct page *um_vdso; @@ -20,18 +21,29 @@ static int __init init_vdso(void) { BUG_ON(vdso_end - vdso_start > PAGE_SIZE); - um_vdso_addr = task_size - PAGE_SIZE; - um_vdso = alloc_page(GFP_KERNEL); if (!um_vdso) panic("Cannot allocate vdso\n"); copy_page(page_address(um_vdso), vdso_start); +#ifdef CONFIG_MMU + um_vdso_addr = task_size - PAGE_SIZE; +#else + /* this is fine with NOMMU as everything is accessible */ + um_vdso_addr = (unsigned long)page_address(um_vdso); + os_protect_memory((void *)um_vdso_addr, vdso_end - vdso_start, 1, 0, 1); +#endif + + pr_info("vdso_start=%lx um_vdso_addr=%lx pg_um_vdso=%lx", + (unsigned long)vdso_start, um_vdso_addr, + (unsigned long)page_address(um_vdso)); + return 0; } subsys_initcall(init_vdso); +#ifdef CONFIG_MMU int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) { struct vm_area_struct *vma; @@ -53,3 +65,4 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp) return IS_ERR(vma) ? PTR_ERR(vma) : 0; } +#endif -- 2.43.0
