On Mon, Feb 24, 2025 at 10:52:43PM +0000, [email protected] wrote: > From: Jeff Xu <[email protected]> > > Provide support for CONFIG_MSEAL_SYSTEM_MAPPINGS on arm64, covering > the vdso, vvar, and compat-mode vectors and sigpage mappings. > > Production release testing passes on Android and Chrome OS.
This is pretty limited (yes yes I know android is massive etc. but we must account for all the weird and wonderful arm64 devices out there in context of upstream :) Have you looking through all arm64-code relating to vdso, vvar, compat-mode vectors, sigpage mapping and ensured nothing kernel-side relies upon relocation? Some arches actually seem to want to do this. Pretty sure PPC does... so a bit nervous of that. At any rate some comment about having checked/confirmed this would be good, arm concerns me a lot more than x86 on this front. Thanks however for doing extensive testing android/chrome side! This is of course, very important for sheer volume (and probably worldwide % of deployed arm64 devices...) Just need to dot our i's and cross our t's... > > Signed-off-by: Jeff Xu <[email protected]> > --- > arch/arm64/Kconfig | 1 + > arch/arm64/kernel/vdso.c | 22 +++++++++++++++------- > 2 files changed, 16 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index fcdd0ed3eca8..39202aa9a5af 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -38,6 +38,7 @@ config ARM64 > select ARCH_HAS_KEEPINITRD > select ARCH_HAS_MEMBARRIER_SYNC_CORE > select ARCH_HAS_MEM_ENCRYPT > + select ARCH_HAS_MSEAL_SYSTEM_MAPPINGS > select ARCH_HAS_NMI_SAFE_THIS_CPU_OPS > select ARCH_HAS_NON_OVERLAPPING_ADDRESS_SPACE > select ARCH_HAS_NONLEAF_PMD_YOUNG if ARM64_HAFT > diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c > index e8ed8e5b713b..12e6ab396018 100644 > --- a/arch/arm64/kernel/vdso.c > +++ b/arch/arm64/kernel/vdso.c > @@ -183,6 +183,7 @@ static int __setup_additional_pages(enum vdso_abi abi, > { > unsigned long vdso_base, vdso_text_len, vdso_mapping_len; > unsigned long gp_flags = 0; > + unsigned long vm_flags; > void *ret; > > BUILD_BUG_ON(VVAR_NR_PAGES != __VVAR_PAGES); > @@ -197,8 +198,10 @@ static int __setup_additional_pages(enum vdso_abi abi, > goto up_fail; > } > > + vm_flags = VM_READ|VM_MAYREAD|VM_PFNMAP; > + vm_flags |= VM_SEALED_SYSMAP; > ret = _install_special_mapping(mm, vdso_base, VVAR_NR_PAGES * PAGE_SIZE, > - VM_READ|VM_MAYREAD|VM_PFNMAP, > + vm_flags, > &vvar_map); > if (IS_ERR(ret)) > goto up_fail; > @@ -208,9 +211,10 @@ static int __setup_additional_pages(enum vdso_abi abi, > > vdso_base += VVAR_NR_PAGES * PAGE_SIZE; > mm->context.vdso = (void *)vdso_base; > + vm_flags = VM_READ|VM_EXEC|gp_flags|VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC; > + vm_flags |= VM_SEALED_SYSMAP; > ret = _install_special_mapping(mm, vdso_base, vdso_text_len, > - VM_READ|VM_EXEC|gp_flags| > - VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC, > + vm_flags, > vdso_info[abi].cm); > if (IS_ERR(ret)) > goto up_fail; > @@ -326,6 +330,7 @@ arch_initcall(aarch32_alloc_vdso_pages); > static int aarch32_kuser_helpers_setup(struct mm_struct *mm) > { > void *ret; > + unsigned long vm_flags; > > if (!IS_ENABLED(CONFIG_KUSER_HELPERS)) > return 0; > @@ -334,9 +339,10 @@ static int aarch32_kuser_helpers_setup(struct mm_struct > *mm) > * Avoid VM_MAYWRITE for compatibility with arch/arm/, where it's > * not safe to CoW the page containing the CPU exception vectors. > */ > + vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYEXEC; > + vm_flags |= VM_SEALED_SYSMAP; > ret = _install_special_mapping(mm, AARCH32_VECTORS_BASE, PAGE_SIZE, > - VM_READ | VM_EXEC | > - VM_MAYREAD | VM_MAYEXEC, > + vm_flags, > &aarch32_vdso_maps[AA32_MAP_VECTORS]); > > return PTR_ERR_OR_ZERO(ret); > @@ -345,6 +351,7 @@ static int aarch32_kuser_helpers_setup(struct mm_struct > *mm) > static int aarch32_sigreturn_setup(struct mm_struct *mm) > { > unsigned long addr; > + unsigned long vm_flags; > void *ret; > > addr = get_unmapped_area(NULL, 0, PAGE_SIZE, 0, 0); > @@ -357,9 +364,10 @@ static int aarch32_sigreturn_setup(struct mm_struct *mm) > * VM_MAYWRITE is required to allow gdb to Copy-on-Write and > * set breakpoints. > */ > + vm_flags = VM_READ|VM_EXEC|VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC; > + vm_flags |= VM_SEALED_SYSMAP; > ret = _install_special_mapping(mm, addr, PAGE_SIZE, > - VM_READ | VM_EXEC | VM_MAYREAD | > - VM_MAYWRITE | VM_MAYEXEC, > + vm_flags, > &aarch32_vdso_maps[AA32_MAP_SIGPAGE]); > if (IS_ERR(ret)) > goto out; > -- > 2.48.1.658.g4767266eb4-goog > Patch looks fine for purposes of what you're trying to achieve though, just need to have some calming reassurances about arch :) Thanks!
