Merge tag 'timers-core-2020-01-27' of git://git.kernel.org/pub/scm/li…

…nux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 "The timekeeping and timers departement provides:

   - Time namespace support:

     If a container migrates from one host to another then it expects
     that clocks based on MONOTONIC and BOOTTIME are not subject to
     disruption. Due to different boot time and non-suspended runtime
     these clocks can differ significantly on two hosts, in the worst
     case time goes backwards which is a violation of the POSIX
     requirements.

     The time namespace addresses this problem. It allows to set offsets
     for clock MONOTONIC and BOOTTIME once after creation and before
     tasks are associated with the namespace. These offsets are taken
     into account by timers and timekeeping including the VDSO.

     Offsets for wall clock based clocks (REALTIME/TAI) are not provided
     by this mechanism. While in theory possible, the overhead and code
     complexity would be immense and not justified by the esoteric
     potential use cases which were discussed at Plumbers '18.

     The overhead for tasks in the root namespace (ie where host time
     offsets = 0) is in the noise and great effort was made to ensure
     that especially in the VDSO. If time namespace is disabled in the
     kernel configuration the code is compiled out.

     Kudos to Andrei Vagin and Dmitry Sofanov who implemented this
     feature and kept on for more than a year addressing review
     comments, finding better solutions. A pleasant experience.

   - Overhaul of the alarmtimer device dependency handling to ensure
     that the init/suspend/resume ordering is correct.

   - A new clocksource/event driver for Microchip PIT64

   - Suspend/resume support for the Hyper-V clocksource

   - The usual pile of fixes, updates and improvements mostly in the
     driver code"

* tag 'timers-core-2020-01-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (71 commits)
  alarmtimer: Make alarmtimer_get_rtcdev() a stub when CONFIG_RTC_CLASS=n
  alarmtimer: Use wakeup source from alarmtimer platform device
  alarmtimer: Make alarmtimer platform device child of RTC device
  alarmtimer: Update alarmtimer_get_rtcdev() docs to reflect reality
  hrtimer: Add missing sparse annotation for __run_timer()
  lib/vdso: Only read hrtimer_res when needed in __cvdso_clock_getres()
  MIPS: vdso: Define BUILD_VDSO32 when building a 32bit kernel
  clocksource/drivers/hyper-v: Set TSC clocksource as default w/ InvariantTSC
  clocksource/drivers/hyper-v: Untangle stimers and timesync from clocksources
  clocksource/drivers/timer-microchip-pit64b: Fix sparse warning
  clocksource/drivers/exynos_mct: Rename Exynos to lowercase
  clocksource/drivers/timer-ti-dm: Fix uninitialized pointer access
  clocksource/drivers/timer-ti-dm: Switch to platform_get_irq
  clocksource/drivers/timer-ti-dm: Convert to devm_platform_ioremap_resource
  clocksource/drivers/em_sti: Fix variable declaration in em_sti_probe
  clocksource/drivers/em_sti: Convert to devm_platform_ioremap_resource
  clocksource/drivers/bcm2835_timer: Fix memory leak of timer
  clocksource/drivers/cadence-ttc: Use ttc driver as platform driver
  clocksource/drivers/timer-microchip-pit64b: Add Microchip PIT64B support
  clocksource/drivers/hyper-v: Reserve PAGE_SIZE space for tsc page
  ...

Documentation/devicetree/bindings/arm/atmel-sysregs.txt

@@ -10,6 +10,12 @@ PIT Timer required properties:
 - interrupts: Should contain interrupt for the PIT which is the IRQ line
   shared across all System Controller members.
 
+PIT64B Timer required properties:
+- compatible: Should be "microchip,sam9x60-pit64b"
+- reg: Should contain registers location and length
+- interrupts: Should contain interrupt for PIT64B timer
+- clocks: Should contain the available clock sources for PIT64B timer.
+
 System Timer (ST) required properties:
 - compatible: Should be "atmel,at91rm9200-st", "syscon", "simple-mfd"
 - reg: Should contain registers location and length

Documentation/devicetree/bindings/timer/renesas,cmt.txt

@@ -29,6 +29,8 @@ Required Properties:
     - "renesas,r8a77470-cmt1" for the 48-bit CMT1 device included in r8a77470.
     - "renesas,r8a774a1-cmt0" for the 32-bit CMT0 device included in r8a774a1.
     - "renesas,r8a774a1-cmt1" for the 48-bit CMT devices included in r8a774a1.
+    - "renesas,r8a774b1-cmt0" for the 32-bit CMT0 device included in r8a774b1.
+    - "renesas,r8a774b1-cmt1" for the 48-bit CMT devices included in r8a774b1.
     - "renesas,r8a774c0-cmt0" for the 32-bit CMT0 device included in r8a774c0.
     - "renesas,r8a774c0-cmt1" for the 48-bit CMT devices included in r8a774c0.
     - "renesas,r8a7790-cmt0" for the 32-bit CMT0 device included in r8a7790.

MAINTAINERS

@@ -13258,6 +13258,8 @@ T:	git git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git timers/core
 S:	Maintained
 F:	fs/timerfd.c
 F:	include/linux/timer*
+F:	include/linux/time_namespace.h
+F:	kernel/time_namespace.c
 F:	kernel/time/*timer*
 
 POWER MANAGEMENT CORE

arch/arm/include/asm/vdso/gettimeofday.h

@@ -52,6 +52,24 @@ static __always_inline long clock_gettime_fallback(
 	return ret;
 }
 
+static __always_inline long clock_gettime32_fallback(
+					clockid_t _clkid,
+					struct old_timespec32 *_ts)
+{
+	register struct old_timespec32 *ts asm("r1") = _ts;
+	register clockid_t clkid asm("r0") = _clkid;
+	register long ret asm ("r0");
+	register long nr asm("r7") = __NR_clock_gettime;
+
+	asm volatile(
+	"	swi #0\n"
+	: "=r" (ret)
+	: "r" (clkid), "r" (ts), "r" (nr)
+	: "memory");
+
+	return ret;
+}
+
 static __always_inline int clock_getres_fallback(
 					clockid_t _clkid,
 					struct __kernel_timespec *_ts)
@@ -70,6 +88,24 @@ static __always_inline int clock_getres_fallback(
 	return ret;
 }
 
+static __always_inline int clock_getres32_fallback(
+					clockid_t _clkid,
+					struct old_timespec32 *_ts)
+{
+	register struct old_timespec32 *ts asm("r1") = _ts;
+	register clockid_t clkid asm("r0") = _clkid;
+	register long ret asm ("r0");
+	register long nr asm("r7") = __NR_clock_getres;
+
+	asm volatile(
+	"       swi #0\n"
+	: "=r" (ret)
+	: "r" (clkid), "r" (ts), "r" (nr)
+	: "memory");
+
+	return ret;
+}
+
 static __always_inline u64 __arch_get_hw_counter(int clock_mode)
 {
 #ifdef CONFIG_ARM_ARCH_TIMER

arch/arm/vdso/Makefile

@@ -14,7 +14,7 @@ targets := $(obj-vdso) vdso.so vdso.so.dbg vdso.so.raw vdso.lds
 obj-vdso := $(addprefix $(obj)/, $(obj-vdso))
 
 ccflags-y := -fPIC -fno-common -fno-builtin -fno-stack-protector
-ccflags-y += -DDISABLE_BRANCH_PROFILING
+ccflags-y += -DDISABLE_BRANCH_PROFILING -DBUILD_VDSO32
 
 ldflags-$(CONFIG_CPU_ENDIAN_BE8) := --be8
 ldflags-y := -Bsymbolic --no-undefined -soname=linux-vdso.so.1 \

arch/arm64/include/asm/vdso/compat_gettimeofday.h

@@ -16,7 +16,7 @@
 
 #define VDSO_HAS_CLOCK_GETRES		1
 
-#define VDSO_HAS_32BIT_FALLBACK		1
+#define BUILD_VDSO32			1
 
 static __always_inline
 int gettimeofday_fallback(struct __kernel_old_timeval *_tv,

arch/mips/include/asm/vdso/gettimeofday.h

@@ -96,8 +96,6 @@ static __always_inline int clock_getres_fallback(
 
 #if _MIPS_SIM != _MIPS_SIM_ABI64
 
-#define VDSO_HAS_32BIT_FALLBACK	1
-
 static __always_inline long clock_gettime32_fallback(
 					clockid_t _clkid,
 					struct old_timespec32 *_ts)

arch/mips/vdso/Makefile

@@ -18,6 +18,10 @@ ccflags-vdso := \
 	$(filter -mno-loongson-%,$(KBUILD_CFLAGS)) \
 	-D__VDSO__
 
+ifndef CONFIG_64BIT
+ccflags-vdso += -DBUILD_VDSO32
+endif
+
 ifdef CONFIG_CC_IS_CLANG
 ccflags-vdso += $(filter --target=%,$(KBUILD_CFLAGS))
 endif

arch/x86/Kconfig

@@ -124,6 +124,7 @@ config X86
 	select GENERIC_STRNLEN_USER
 	select GENERIC_TIME_VSYSCALL
 	select GENERIC_GETTIMEOFDAY
+	select GENERIC_VDSO_TIME_NS
 	select GUP_GET_PTE_LOW_HIGH		if X86_PAE
 	select HARDLOCKUP_CHECK_TIMESTAMP	if X86_64
 	select HAVE_ACPI_APEI			if ACPI

arch/x86/entry/vdso/vdso-layout.lds.S

@@ -16,18 +16,23 @@ SECTIONS
 	 * segment.
 	 */
 
-	vvar_start = . - 3 * PAGE_SIZE;
-	vvar_page = vvar_start;
+	vvar_start = . - 4 * PAGE_SIZE;
+	vvar_page  = vvar_start;
 
 	/* Place all vvars at the offsets in asm/vvar.h. */
 #define EMIT_VVAR(name, offset) vvar_ ## name = vvar_page + offset;
-#define __VVAR_KERNEL_LDS
 #include <asm/vvar.h>
-#undef __VVAR_KERNEL_LDS
 #undef EMIT_VVAR
 
 	pvclock_page = vvar_start + PAGE_SIZE;
 	hvclock_page = vvar_start + 2 * PAGE_SIZE;
+	timens_page  = vvar_start + 3 * PAGE_SIZE;
+
+#undef _ASM_X86_VVAR_H
+	/* Place all vvars in timens too at the offsets in asm/vvar.h. */
+#define EMIT_VVAR(name, offset) timens_ ## name = timens_page + offset;
+#include <asm/vvar.h>
+#undef EMIT_VVAR
 
 	. = SIZEOF_HEADERS;
 

arch/x86/entry/vdso/vdso2c.c

@@ -75,12 +75,14 @@ enum {
 	sym_vvar_page,
 	sym_pvclock_page,
 	sym_hvclock_page,
+	sym_timens_page,
 };
 
 const int special_pages[] = {
 	sym_vvar_page,
 	sym_pvclock_page,
 	sym_hvclock_page,
+	sym_timens_page,
 };
 
 struct vdso_sym {
@@ -93,6 +95,7 @@ struct vdso_sym required_syms[] = {
 	[sym_vvar_page] = {"vvar_page", true},
 	[sym_pvclock_page] = {"pvclock_page", true},
 	[sym_hvclock_page] = {"hvclock_page", true},
+	[sym_timens_page] = {"timens_page", true},
 	{"VDSO32_NOTE_MASK", true},
 	{"__kernel_vsyscall", true},
 	{"__kernel_sigreturn", true},

arch/x86/entry/vdso/vma.c

@@ -14,16 +14,30 @@
 #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>
 #include <asm/vdso.h>
 #include <asm/vvar.h>
+#include <asm/tlb.h>
 #include <asm/page.h>
 #include <asm/desc.h>
 #include <asm/cpufeature.h>
 #include <clocksource/hyperv_timer.h>
 
+#undef _ASM_X86_VVAR_H
+#define EMIT_VVAR(name, offset)	\
+	const size_t name ## _offset = offset;
+#include <asm/vvar.h>
+
+struct vdso_data *arch_get_vdso_data(void *vvar_page)
+{
+	return (struct vdso_data *)(vvar_page + _vdso_data_offset);
+}
+#undef EMIT_VVAR
+
 #if defined(CONFIG_X86_64)
 unsigned int __read_mostly vdso64_enabled = 1;
 #endif
@@ -37,6 +51,7 @@ void __init init_vdso_image(const struct vdso_image *image)
 						image->alt_len));
 }
 
+static const struct vm_special_mapping vvar_mapping;
 struct linux_binprm;
 
 static vm_fault_t vdso_fault(const struct vm_special_mapping *sm,
@@ -84,10 +99,74 @@ static int vdso_mremap(const struct vm_special_mapping *sm,
 	return 0;
 }
 
+static int vvar_mremap(const struct vm_special_mapping *sm,
+		struct vm_area_struct *new_vma)
+{
+	const struct vdso_image *image = new_vma->vm_mm->context.vdso_image;
+	unsigned long new_size = new_vma->vm_end - new_vma->vm_start;
+
+	if (new_size != -image->sym_vvar_start)
+		return -EINVAL;
+
+	return 0;
+}
+
+#ifdef CONFIG_TIME_NS
+static struct page *find_timens_vvar_page(struct vm_area_struct *vma)
+{
+	if (likely(vma->vm_mm == current->mm))
+		return current->nsproxy->time_ns->vvar_page;
+
+	/*
+	 * VM_PFNMAP | VM_IO protect .fault() handler from being called
+	 * through interfaces like /proc/$pid/mem or
+	 * process_vm_{readv,writev}() as long as there's no .access()
+	 * in special_mapping_vmops().
+	 * For more details check_vma_flags() and __access_remote_vm()
+	 */
+
+	WARN(1, "vvar_page accessed remotely");
+
+	return NULL;
+}
+
+/*
+ * The vvar page layout depends on whether a task belongs to the root or
+ * non-root time namespace. Whenever a task changes its namespace, the VVAR
+ * page tables are cleared and then they will re-faulted with a
+ * corresponding layout.
+ * See also the comment near timens_setup_vdso_data() for details.
+ */
+int vdso_join_timens(struct task_struct *task, struct time_namespace *ns)
+{
+	struct mm_struct *mm = task->mm;
+	struct vm_area_struct *vma;
+
+	if (down_write_killable(&mm->mmap_sem))
+		return -EINTR;
+
+	for (vma = mm->mmap; vma; vma = vma->vm_next) {
+		unsigned long size = vma->vm_end - vma->vm_start;
+
+		if (vma_is_special_mapping(vma, &vvar_mapping))
+			zap_page_range(vma, vma->vm_start, size);
+	}
+
+	up_write(&mm->mmap_sem);
+	return 0;
+}
+#else
+static inline struct page *find_timens_vvar_page(struct vm_area_struct *vma)
+{
+	return NULL;
+}
+#endif
+
 static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		      struct vm_area_struct *vma, struct vm_fault *vmf)
 {
 	const struct vdso_image *image = vma->vm_mm->context.vdso_image;
+	unsigned long pfn;
 	long sym_offset;
 
 	if (!image)
@@ -107,8 +186,36 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		return VM_FAULT_SIGBUS;
 
 	if (sym_offset == image->sym_vvar_page) {
-		return vmf_insert_pfn(vma, vmf->address,
-				__pa_symbol(&__vvar_page) >> PAGE_SHIFT);
+		struct page *timens_page = find_timens_vvar_page(vma);
+
+		pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
+
+		/*
+		 * If a task belongs to a time namespace then a namespace
+		 * specific VVAR is mapped with the sym_vvar_page offset and
+		 * the real VVAR page is mapped with the sym_timens_page
+		 * offset.
+		 * See also the comment near timens_setup_vdso_data().
+		 */
+		if (timens_page) {
+			unsigned long addr;
+			vm_fault_t err;
+
+			/*
+			 * Optimization: inside time namespace pre-fault
+			 * VVAR page too. As on timens page there are only
+			 * offsets for clocks on VVAR, it'll be faulted
+			 * shortly by VDSO code.
+			 */
+			addr = vmf->address + (image->sym_timens_page - sym_offset);
+			err = vmf_insert_pfn(vma, addr, pfn);
+			if (unlikely(err & VM_FAULT_ERROR))
+				return err;
+
+			pfn = page_to_pfn(timens_page);
+		}
+
+		return vmf_insert_pfn(vma, vmf->address, pfn);
 	} else if (sym_offset == image->sym_pvclock_page) {
 		struct pvclock_vsyscall_time_info *pvti =
 			pvclock_get_pvti_cpu0_va();
@@ -123,6 +230,14 @@ static vm_fault_t vvar_fault(const struct vm_special_mapping *sm,
 		if (tsc_pg && vclock_was_used(VCLOCK_HVCLOCK))
 			return vmf_insert_pfn(vma, vmf->address,
 					virt_to_phys(tsc_pg) >> PAGE_SHIFT);
+	} else if (sym_offset == image->sym_timens_page) {
+		struct page *timens_page = find_timens_vvar_page(vma);
+
+		if (!timens_page)
+			return VM_FAULT_SIGBUS;
+
+		pfn = __pa_symbol(&__vvar_page) >> PAGE_SHIFT;
+		return vmf_insert_pfn(vma, vmf->address, pfn);
 	}
 
 	return VM_FAULT_SIGBUS;
@@ -136,6 +251,7 @@ static const struct vm_special_mapping vdso_mapping = {
 static const struct vm_special_mapping vvar_mapping = {
 	.name = "[vvar]",
 	.fault = vvar_fault,
+	.mremap = vvar_mremap,
 };
 
 /*

arch/x86/include/asm/vdso.h

@@ -21,6 +21,7 @@ struct vdso_image {
 	long sym_vvar_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;

arch/x86/include/asm/vdso/gettimeofday.h

@@ -21,6 +21,7 @@
 #include <clocksource/hyperv_timer.h>
 
 #define __vdso_data (VVAR(_vdso_data))
+#define __timens_vdso_data (TIMENS(_vdso_data))
 
 #define VDSO_HAS_TIME 1
 
@@ -56,6 +57,13 @@ extern struct ms_hyperv_tsc_page hvclock_page
 	__attribute__((visibility("hidden")));
 #endif
 
+#ifdef CONFIG_TIME_NS
+static __always_inline const struct vdso_data *__arch_get_timens_vdso_data(void)
+{
+	return __timens_vdso_data;
+}
+#endif
+
 #ifndef BUILD_VDSO32
 
 static __always_inline
@@ -96,8 +104,6 @@ long clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
 
 #else
 
-#define VDSO_HAS_32BIT_FALLBACK	1
-
 static __always_inline
 long clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
 {