| Message ID | 20200624083321.144975-2-avagin@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | arm64: add the time namespace support | expand |
On Fri, Jul 24, 2020 at 06:26:23PM +0100, Catalin Marinas wrote: > On Wed, 24 Jun 2020 01:33:16 -0700, Andrei Vagin wrote: > > Currently the vdso has no awareness of time namespaces, which may > > apply distinct offsets to processes in different namespaces. To handle > > this within the vdso, we'll need to expose a per-namespace data page. > > > > As a preparatory step, this patch separates the vdso data page from > > the code pages, and has it faulted in via its own fault callback. > > Subsquent patches will extend this to support distinct pages per time > > namespace. > > > > [...] > > Applied to arm64 (for-next/timens), provisionally. > > One potential issue I did not check is the compat vDSO. The arm32 port > does not support timens currently. IIUC, with these patches and > COMPAT_VDSO enabled, it will allow timens for compat processes. Normally > I'd like the arm32 support first before updating compat but I don't > think there would be any interface incompatibility here. > > However, does this still work for arm32 processes if COMPAT_VDSO is > disabled in the arm64 kernel? Yes, it does. I checked that the timens test passes with and without COMPAT_VDSO: [avagin@laptop linux]$ git describe HEAD v5.8-rc3-6-g9614cc576d76 alpine:/tip/tools/testing/selftests/timens# readelf -h ./timens ELF Header: Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 Class: ELF32 Data: 2's complement, little endian Version: 1 (current) OS/ABI: UNIX - System V ABI Version: 0 Type: DYN (Shared object file) Machine: ARM Version: 0x1 Entry point address: 0x711 Start of program headers: 52 (bytes into file) Start of section headers: 15444 (bytes into file) Flags: 0x5000400, Version5 EABI, hard-float ABI Size of this header: 52 (bytes) Size of program headers: 32 (bytes) Number of program headers: 7 Size of section headers: 40 (bytes) Number of section headers: 32 Section header string table index: 31 alpine:/tip/tools/testing/selftests/timens# uname -a Linux arm64-alpine 5.8.0-rc3+ #100 SMP Sun Jul 26 23:21:07 PDT 2020 aarch64 Linux [avagin@laptop linux]$ cat .config | grep VDSO CONFIG_COMPAT_VDSO=y CONFIG_THUMB2_COMPAT_VDSO=y CONFIG_HAVE_GENERIC_VDSO=y CONFIG_GENERIC_COMPAT_VDSO=y CONFIG_GENERIC_VDSO_TIME_NS=y alpine:/tip/tools/testing/selftests/timens# ./timens 1..10 ok 1 Passed for CLOCK_BOOTTIME (syscall) ok 2 Passed for CLOCK_BOOTTIME (vdso) not ok 3 # SKIP CLOCK_BOOTTIME_ALARM isn't supported not ok 4 # SKIP CLOCK_BOOTTIME_ALARM isn't supported ok 5 Passed for CLOCK_MONOTONIC (syscall) ok 6 Passed for CLOCK_MONOTONIC (vdso) ok 7 Passed for CLOCK_MONOTONIC_COARSE (syscall) ok 8 Passed for CLOCK_MONOTONIC_COARSE (vdso) ok 9 Passed for CLOCK_MONOTONIC_RAW (syscall) ok 10 Passed for CLOCK_MONOTONIC_RAW (vdso) # Pass 8 Fail 0 Xfail 0 Xpass 0 Skip 2 Error 0 [avagin@laptop linux]$ cat .config | grep VDSO # CONFIG_COMPAT_VDSO is not set CONFIG_HAVE_GENERIC_VDSO=y CONFIG_GENERIC_VDSO_TIME_NS=y alpine:/tip/tools/testing/selftests/timens# ./timens 1..10 ok 1 Passed for CLOCK_BOOTTIME (syscall) ok 2 Passed for CLOCK_BOOTTIME (vdso) not ok 3 # SKIP CLOCK_BOOTTIME_ALARM isn't supported not ok 4 # SKIP CLOCK_BOOTTIME_ALARM isn't supported ok 5 Passed for CLOCK_MONOTONIC (syscall) ok 6 Passed for CLOCK_MONOTONIC (vdso) ok 7 Passed for CLOCK_MONOTONIC_COARSE (syscall) ok 8 Passed for CLOCK_MONOTONIC_COARSE (vdso) ok 9 Passed for CLOCK_MONOTONIC_RAW (syscall) ok 10 Passed for CLOCK_MONOTONIC_RAW (vdso) # Pass 8 Fail 0 Xfail 0 Xpass 0 Skip 2 Error 0 Thanks, Andrei
diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c index 4e016574bd91..7c4620451fa5 100644 --- a/arch/arm64/kernel/vdso.c +++ b/arch/arm64/kernel/vdso.c @@ -107,29 +107,32 @@ static int __vdso_init(enum vdso_abi abi) vdso_info[abi].vdso_code_start) >> PAGE_SHIFT; - /* Allocate the vDSO pagelist, plus a page for the data. */ - vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages + 1, + vdso_pagelist = kcalloc(vdso_info[abi].vdso_pages, sizeof(struct page *), GFP_KERNEL); if (vdso_pagelist == NULL) return -ENOMEM; - /* Grab the vDSO data page. */ - vdso_pagelist[0] = phys_to_page(__pa_symbol(vdso_data)); - - /* Grab the vDSO code pages. */ pfn = sym_to_pfn(vdso_info[abi].vdso_code_start); for (i = 0; i < vdso_info[abi].vdso_pages; i++) - vdso_pagelist[i + 1] = pfn_to_page(pfn + i); + vdso_pagelist[i] = pfn_to_page(pfn + i); - vdso_info[abi].dm->pages = &vdso_pagelist[0]; - vdso_info[abi].cm->pages = &vdso_pagelist[1]; + vdso_info[abi].cm->pages = vdso_pagelist; return 0; } +static vm_fault_t vvar_fault(const struct vm_special_mapping *sm, + struct vm_area_struct *vma, struct vm_fault *vmf) +{ + if (vmf->pgoff == 0) + return vmf_insert_pfn(vma, vmf->address, + sym_to_pfn(vdso_data)); + return VM_FAULT_SIGBUS; +} + static int __setup_additional_pages(enum vdso_abi abi, struct mm_struct *mm, struct linux_binprm *bprm, @@ -150,7 +153,7 @@ static int __setup_additional_pages(enum vdso_abi abi, } ret = _install_special_mapping(mm, vdso_base, PAGE_SIZE, - VM_READ|VM_MAYREAD, + VM_READ|VM_MAYREAD|VM_PFNMAP, vdso_info[abi].dm); if (IS_ERR(ret)) goto up_fail; @@ -209,6 +212,7 @@ static struct vm_special_mapping aarch32_vdso_maps[] = { #ifdef CONFIG_COMPAT_VDSO [AA32_MAP_VVAR] = { .name = "[vvar]", + .fault = vvar_fault, }, [AA32_MAP_VDSO] = { .name = "[vdso]", @@ -376,6 +380,7 @@ enum aarch64_map { static struct vm_special_mapping aarch64_vdso_maps[] __ro_after_init = { [AA64_MAP_VVAR] = { .name = "[vvar]", + .fault = vvar_fault, }, [AA64_MAP_VDSO] = { .name = "[vdso]",