From: Andrei Vagin <[email protected]> As modern applications fetch time from vdso without entering the kernel, it's needed to provide offsets for userspace code.
Allocate a page for timens offsets when constructing time namespace. As vdso mappings are platform-specific, add Kconfig dependency for arch. Signed-off-by: Andrei Vagin <[email protected]> Co-developed-by: Dmitry Safonov <[email protected]> Signed-off-by: Dmitry Safonov <[email protected]> --- arch/Kconfig | 5 +++++ arch/x86/Kconfig | 1 + arch/x86/entry/vdso/vclock_gettime.c | 26 ++++++++++++++++++++++++++ arch/x86/entry/vdso/vdso-layout.lds.S | 9 ++++++++- arch/x86/entry/vdso/vdso2c.c | 3 +++ arch/x86/entry/vdso/vma.c | 12 ++++++++++++ arch/x86/include/asm/vdso.h | 1 + init/Kconfig | 1 + 8 files changed, 57 insertions(+), 1 deletion(-) diff --git a/arch/Kconfig b/arch/Kconfig index 6801123932a5..411df0227a1d 100644 --- a/arch/Kconfig +++ b/arch/Kconfig @@ -681,6 +681,11 @@ config HAVE_ARCH_HASH config ISA_BUS_API def_bool ISA +config ARCH_HAS_VDSO_TIME_NS + bool + help + VDSO can add time-ns offsets without entering kernel. + # # ABI hall of shame # diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 1a0be022f91d..4bcbdd1f1200 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -70,6 +70,7 @@ config X86 select ARCH_HAS_STRICT_MODULE_RWX select ARCH_HAS_SYNC_CORE_BEFORE_USERMODE select ARCH_HAS_UBSAN_SANITIZE_ALL + select ARCH_HAS_VDSO_TIME_NS select ARCH_HAS_ZONE_DEVICE if X86_64 select ARCH_HAVE_NMI_SAFE_CMPXCHG select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI diff --git a/arch/x86/entry/vdso/vclock_gettime.c b/arch/x86/entry/vdso/vclock_gettime.c index f19856d95c60..0594266740b9 100644 --- a/arch/x86/entry/vdso/vclock_gettime.c +++ b/arch/x86/entry/vdso/vclock_gettime.c @@ -21,6 +21,7 @@ #include <linux/math64.h> #include <linux/time.h> #include <linux/kernel.h> +#include <linux/timens_offsets.h> #define gtod (&VVAR(vsyscall_gtod_data)) @@ -38,6 +39,11 @@ extern u8 hvclock_page __attribute__((visibility("hidden"))); #endif +#ifdef CONFIG_TIME_NS +extern u8 timens_page + __attribute__((visibility("hidden"))); +#endif + #ifndef BUILD_VDSO32 notrace static long vdso_fallback_gettime(long clock, struct timespec *ts) @@ -225,6 +231,23 @@ notrace static int __always_inline do_realtime(struct timespec *ts) return mode; } +notrace static __always_inline void monotonic_to_ns(struct timespec *ts) +{ +#ifdef CONFIG_TIME_NS + struct timens_offsets *timens = (struct timens_offsets *) &timens_page; + + ts->tv_sec += timens->monotonic_time_offset.tv_sec; + ts->tv_nsec += timens->monotonic_time_offset.tv_nsec; + if (ts->tv_nsec > NSEC_PER_SEC) { + ts->tv_nsec -= NSEC_PER_SEC; + ts->tv_sec++; + } else if (ts->tv_nsec < 0) { + ts->tv_nsec += NSEC_PER_SEC; + ts->tv_sec--; + } +#endif +} + notrace static int __always_inline do_monotonic(struct timespec *ts) { unsigned long seq; @@ -243,6 +266,8 @@ notrace static int __always_inline do_monotonic(struct timespec *ts) ts->tv_sec += __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns); ts->tv_nsec = ns; + monotonic_to_ns(ts); + return mode; } @@ -264,6 +289,7 @@ notrace static void do_monotonic_coarse(struct timespec *ts) ts->tv_sec = gtod->monotonic_time_coarse_sec; ts->tv_nsec = gtod->monotonic_time_coarse_nsec; } while (unlikely(gtod_read_retry(gtod, seq))); + monotonic_to_ns(ts); } notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts) diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S index acfd5ba7d943..e5c2e9deca03 100644 --- a/arch/x86/entry/vdso/vdso-layout.lds.S +++ b/arch/x86/entry/vdso/vdso-layout.lds.S @@ -17,6 +17,12 @@ #define NUM_FAKE_SHDRS 13 +#ifdef CONFIG_TIME_NS +# define TIMENS_SZ PAGE_SIZE +#else +# define TIMENS_SZ 0 +#endif + SECTIONS { /* @@ -26,7 +32,7 @@ SECTIONS * segment. */ - vvar_start = . - 3 * PAGE_SIZE; + vvar_start = . - (3 * PAGE_SIZE + TIMENS_SZ); vvar_page = vvar_start; /* Place all vvars at the offsets in asm/vvar.h. */ @@ -38,6 +44,7 @@ SECTIONS pvclock_page = vvar_start + PAGE_SIZE; hvclock_page = vvar_start + 2 * PAGE_SIZE; + timens_page = vvar_start + 3 * PAGE_SIZE; . = SIZEOF_HEADERS; diff --git a/arch/x86/entry/vdso/vdso2c.c b/arch/x86/entry/vdso/vdso2c.c index 4674f58581a1..6c67cde7fe99 100644 --- a/arch/x86/entry/vdso/vdso2c.c +++ b/arch/x86/entry/vdso/vdso2c.c @@ -76,6 +76,7 @@ enum { sym_hpet_page, sym_pvclock_page, sym_hvclock_page, + sym_timens_page, sym_VDSO_FAKE_SECTION_TABLE_START, sym_VDSO_FAKE_SECTION_TABLE_END, }; @@ -85,6 +86,7 @@ const int special_pages[] = { sym_hpet_page, sym_pvclock_page, sym_hvclock_page, + sym_timens_page, }; struct vdso_sym { @@ -98,6 +100,7 @@ struct vdso_sym required_syms[] = { [sym_hpet_page] = {"hpet_page", true}, [sym_pvclock_page] = {"pvclock_page", true}, [sym_hvclock_page] = {"hvclock_page", true}, + [sym_timens_page] = {"timens_page", true}, [sym_VDSO_FAKE_SECTION_TABLE_START] = { "VDSO_FAKE_SECTION_TABLE_START", false }, diff --git a/arch/x86/entry/vdso/vma.c b/arch/x86/entry/vdso/vma.c index 8cc0395687b0..0f92227a4a7e 100644 --- a/arch/x86/entry/vdso/vma.c +++ b/arch/x86/entry/vdso/vma.c @@ -14,6 +14,7 @@ #include <linux/elf.h> #include <linux/cpu.h> #include <linux/ptrace.h> +#include <linux/time_namespace.h> #include <asm/pvclock.h> #include <asm/vgtod.h> #include <asm/proto.h> @@ -23,6 +24,7 @@ #include <asm/desc.h> #include <asm/cpufeature.h> #include <asm/mshyperv.h> +#include <asm/page.h> #if defined(CONFIG_X86_64) unsigned int __read_mostly vdso64_enabled = 1; @@ -138,6 +140,16 @@ static int vvar_fault(const struct vm_special_mapping *sm, if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK)) ret = vm_insert_pfn(vma, vmf->address, vmalloc_to_pfn(tsc_pg)); + } else if (sym_offset == image->sym_timens_page) { + struct time_namespace *ns = current->nsproxy->time_ns; + unsigned long pfn; + + if (!ns->offsets) + pfn = page_to_pfn(ZERO_PAGE(0)); + else + pfn = page_to_pfn(virt_to_page(ns->offsets)); + + ret = vm_insert_pfn(vma, vmf->address, pfn); } if (ret == 0 || ret == -EBUSY) diff --git a/arch/x86/include/asm/vdso.h b/arch/x86/include/asm/vdso.h index 27566e57e87d..619322065b8e 100644 --- a/arch/x86/include/asm/vdso.h +++ b/arch/x86/include/asm/vdso.h @@ -22,6 +22,7 @@ struct vdso_image { long sym_hpet_page; long sym_pvclock_page; long sym_hvclock_page; + long sym_timens_page; long sym_VDSO32_NOTE_MASK; long sym___kernel_sigreturn; long sym___kernel_rt_sigreturn; diff --git a/init/Kconfig b/init/Kconfig index dc2b40f7d73f..c9b250475ddb 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -929,6 +929,7 @@ config UTS_NS config TIME_NS bool "TIME namespace" + depends on ARCH_HAS_VDSO_TIME_NS default y help In this namespace boottime and monotonic clocks can be set. -- 2.13.6
