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* [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation.
@ 2020-01-13 17:08 Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 01/12] powerpc/64: Don't provide time functions in compat VDSO32 Christophe Leroy
                   ` (11 more replies)
  0 siblings, 12 replies; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

This is a third tentative to switch powerpc VDSO to generic C implementation.

This version should work on PPC64 (untested). VDSO32 for PPC64 is
impossible to build and has been de-activated, because the powerpc
ASM header files for C are not prepared to build 32 bits code with CONFIG_PPC64.

powerpc is a bit special for VDSO as well as system calls in the
way that it requires setting CR SO bit which cannot be done in C.
Therefore, entry/exit and fallback need to be performed in ASM.

On a powerpc8xx, with current powerpc/32 ASM VDSO:

gettimeofday:    vdso: 737 nsec/call
clock-getres-realtime:    vdso: 475 nsec/call
clock-gettime-realtime:    vdso: 892 nsec/call

The first patch adds VDSO generic C support without any changes to common code.
Performance is as follows:

gettimeofday:    vdso: 1379 nsec/call
clock-getres-realtime-coarse:    vdso: 984 nsec/call
clock-gettime-realtime-coarse:    vdso: 868 nsec/call
clock-getres-realtime:    vdso: 922 nsec/call
clock-gettime-realtime:    vdso: 1511 nsec/call
clock-getres-monotonic-raw:    vdso: 968 nsec/call
clock-gettime-monotonic-raw:    vdso: 1576 nsec/call

Then a few changes in the common code have allowed performance improvement. At
the end of the series we have:

gettimeofday:    vdso: 899 nsec/call
clock-getres-realtime-coarse:    vdso: 546 nsec/call
clock-gettime-realtime-coarse:    vdso: 615 nsec/call
clock-getres-realtime:    vdso: 545 nsec/call
clock-gettime-realtime:    vdso: 1064 nsec/call
clock-getres-monotonic-raw:    vdso: 546 nsec/call
clock-gettime-monotonic-raw:    vdso: 1125 nsec/call

Christophe Leroy (12):
  powerpc/64: Don't provide time functions in compat VDSO32
  powerpc/vdso: Switch VDSO to generic C implementation.
  lib: vdso: mark __cvdso_clock_getres() as static
  lib: vdso: inline do_hres() and do_coarse()
  lib: vdso: Avoid duplication in __cvdso_clock_getres()
  lib: vdso: __iter_div_u64_rem() is suboptimal for 32 bit time
  powerpc/vdso: simplify __get_datapage()
  lib: vdso: allow arches to provide vdso data pointer
  powerpc/vdso: provide inline alternative to __get_datapage()
  powerpc/vdso: provide vdso data pointer from the ASM caller.
  lib: vdso: split clock verification out of __arch_get_hw_counter()
  powerpc/vdso: provide __arch_is_hw_counter_valid()

 arch/powerpc/Kconfig                         |   2 +
 arch/powerpc/include/asm/vdso/gettimeofday.h | 104 +++++++++++
 arch/powerpc/include/asm/vdso/vsyscall.h     |  25 +++
 arch/powerpc/include/asm/vdso_datapage.h     |  52 +++---
 arch/powerpc/kernel/asm-offsets.c            |  46 +----
 arch/powerpc/kernel/time.c                   |  90 ----------
 arch/powerpc/kernel/vdso.c                   |  58 ++----
 arch/powerpc/kernel/vdso32/Makefile          |  30 +++-
 arch/powerpc/kernel/vdso32/datapage.S        |  10 +-
 arch/powerpc/kernel/vdso32/gettimeofday.S    | 258 ++++-----------------------
 arch/powerpc/kernel/vdso32/vdso32.lds.S      |   9 +-
 arch/powerpc/kernel/vdso32/vgettimeofday.c   |  29 +++
 arch/powerpc/kernel/vdso64/Makefile          |  23 ++-
 arch/powerpc/kernel/vdso64/datapage.S        |  13 +-
 arch/powerpc/kernel/vdso64/gettimeofday.S    | 257 ++++----------------------
 arch/powerpc/kernel/vdso64/vdso64.lds.S      |   7 +-
 arch/powerpc/kernel/vdso64/vgettimeofday.c   |  29 +++
 lib/vdso/gettimeofday.c                      | 130 +++++++++++---
 18 files changed, 457 insertions(+), 715 deletions(-)
 create mode 100644 arch/powerpc/include/asm/vdso/gettimeofday.h
 create mode 100644 arch/powerpc/include/asm/vdso/vsyscall.h
 create mode 100644 arch/powerpc/kernel/vdso32/vgettimeofday.c
 create mode 100644 arch/powerpc/kernel/vdso64/vgettimeofday.c

-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 01/12] powerpc/64: Don't provide time functions in compat VDSO32
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 02/12] powerpc/vdso: Switch VDSO to generic C implementation Christophe Leroy
                   ` (10 subsequent siblings)
  11 siblings, 0 replies; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

In order to allow use of generic C VDSO, remove time functions
from the 32 bits VDSO on PPC64.

This (temporary) removal is needed because powerpc kernel C headers
are not prepared for building 32 bits code on PPC64.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/kernel/vdso32/Makefile     | 3 ++-
 arch/powerpc/kernel/vdso32/vdso32.lds.S | 2 +-
 2 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/kernel/vdso32/Makefile b/arch/powerpc/kernel/vdso32/Makefile
index 06f54d947057..738d52105392 100644
--- a/arch/powerpc/kernel/vdso32/Makefile
+++ b/arch/powerpc/kernel/vdso32/Makefile
@@ -3,7 +3,8 @@
 # List of files in the vdso, has to be asm only for now
 
 obj-vdso32-$(CONFIG_PPC64) = getcpu.o
-obj-vdso32 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o \
+obj-vdso32-$(CONFIG_PPC32) = gettimeofday.o
+obj-vdso32 = sigtramp.o datapage.o cacheflush.o note.o \
 		$(obj-vdso32-y)
 
 # Build rules
diff --git a/arch/powerpc/kernel/vdso32/vdso32.lds.S b/arch/powerpc/kernel/vdso32/vdso32.lds.S
index 00c025ba4a92..9400b182e163 100644
--- a/arch/powerpc/kernel/vdso32/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso32/vdso32.lds.S
@@ -144,7 +144,7 @@ VERSION
 		__kernel_datapage_offset;
 
 		__kernel_get_syscall_map;
-#ifndef CONFIG_PPC_BOOK3S_601
+#if defined(CONFIG_PPC32) && !defined(CONFIG_PPC_BOOK3S_601)
 		__kernel_gettimeofday;
 		__kernel_clock_gettime;
 		__kernel_clock_getres;
-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 02/12] powerpc/vdso: Switch VDSO to generic C implementation.
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 01/12] powerpc/64: Don't provide time functions in compat VDSO32 Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 03/12] lib: vdso: mark __cvdso_clock_getres() as static Christophe Leroy
                   ` (9 subsequent siblings)
  11 siblings, 0 replies; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

This is a minimalistic conversion to VDSO generic C implementation.

On powerpc 8xx, performance is degraded by 40-45% for gettime and
by 50% for getres.

Optimisations will follow in next patches, some in the core
VDSO functions, some in the powerpc arch.

powerpc is a bit special for VDSO as well as system calls in the
way that it requires setting CR SO bit which cannot be done in C.
Therefore, entry/exit needs to be performed in ASM.

On a powerpc885 at 132MHz:
With current powerpc/32 ASM VDSO:

gettimeofday:    vdso: 737 nsec/call
clock-getres-realtime-coarse:    vdso: 3081 nsec/call
clock-gettime-realtime-coarse:    vdso: 2861 nsec/call
clock-getres-realtime:    vdso: 475 nsec/call
clock-gettime-realtime:    vdso: 892 nsec/call
clock-getres-boottime:    vdso: 2621 nsec/call
clock-gettime-boottime:    vdso: 3857 nsec/call
clock-getres-tai:    vdso: 2620 nsec/call
clock-gettime-tai:    vdso: 3854 nsec/call
clock-getres-monotonic-raw:    vdso: 2621 nsec/call
clock-gettime-monotonic-raw:    vdso: 3499 nsec/call
clock-getres-monotonic-coarse:    vdso: 3083 nsec/call
clock-gettime-monotonic-coarse:    vdso: 3082 nsec/call
clock-getres-monotonic:    vdso: 475 nsec/call
clock-gettime-monotonic:    vdso: 1014 nsec/call

Once switched to C implementation:

gettimeofday:    vdso: 1379 nsec/call
getcpu:    vdso: not tested
clock-getres-realtime-coarse:    vdso: 984 nsec/call
clock-gettime-realtime-coarse:    vdso: 868 nsec/call
clock-getres-realtime:    vdso: 922 nsec/call
clock-gettime-realtime:    vdso: 1511 nsec/call
clock-getres-boottime:    vdso: 922 nsec/call
clock-gettime-boottime:    vdso: 1510 nsec/call
clock-getres-tai:    vdso: 923 nsec/call
clock-gettime-tai:    vdso: 1511 nsec/call
clock-getres-monotonic-raw:    vdso: 968 nsec/call
clock-gettime-monotonic-raw:    vdso: 1576 nsec/call
clock-getres-monotonic-coarse:    vdso: 984 nsec/call
clock-gettime-monotonic-coarse:    vdso: 868 nsec/call
clock-getres-monotonic:    vdso: 922 nsec/call
clock-gettime-monotonic:    vdso: 1510 nsec/call
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/Kconfig                         |   2 +
 arch/powerpc/include/asm/vdso/gettimeofday.h | 109 ++++++++++++
 arch/powerpc/include/asm/vdso/vsyscall.h     |  25 +++
 arch/powerpc/include/asm/vdso_datapage.h     |  41 ++---
 arch/powerpc/kernel/asm-offsets.c            |  46 +----
 arch/powerpc/kernel/time.c                   |  90 ----------
 arch/powerpc/kernel/vdso.c                   |   5 +-
 arch/powerpc/kernel/vdso32/Makefile          |  27 ++-
 arch/powerpc/kernel/vdso32/gettimeofday.S    | 255 +++------------------------
 arch/powerpc/kernel/vdso32/vgettimeofday.c   |  26 +++
 arch/powerpc/kernel/vdso64/Makefile          |  23 ++-
 arch/powerpc/kernel/vdso64/datapage.S        |   3 +-
 arch/powerpc/kernel/vdso64/gettimeofday.S    | 254 +++-----------------------
 arch/powerpc/kernel/vdso64/vgettimeofday.c   |  26 +++
 14 files changed, 312 insertions(+), 620 deletions(-)
 create mode 100644 arch/powerpc/include/asm/vdso/gettimeofday.h
 create mode 100644 arch/powerpc/include/asm/vdso/vsyscall.h
 create mode 100644 arch/powerpc/kernel/vdso32/vgettimeofday.c
 create mode 100644 arch/powerpc/kernel/vdso64/vgettimeofday.c

diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 1ec34e16ed65..bd04c68baf91 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -169,6 +169,7 @@ config PPC
 	select GENERIC_STRNCPY_FROM_USER
 	select GENERIC_STRNLEN_USER
 	select GENERIC_TIME_VSYSCALL
+	select GENERIC_GETTIMEOFDAY
 	select HAVE_ARCH_AUDITSYSCALL
 	select HAVE_ARCH_HUGE_VMAP		if PPC_BOOK3S_64 && PPC_RADIX_MMU
 	select HAVE_ARCH_JUMP_LABEL
@@ -198,6 +199,7 @@ config PPC
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_FUNCTION_TRACER
 	select HAVE_GCC_PLUGINS			if GCC_VERSION >= 50200   # plugin support on gcc <= 5.1 is buggy on PPC
+	select HAVE_GENERIC_VDSO
 	select HAVE_HW_BREAKPOINT		if PERF_EVENTS && (PPC_BOOK3S || PPC_8xx)
 	select HAVE_IDE
 	select HAVE_IOREMAP_PROT
diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
new file mode 100644
index 000000000000..343c81a7e951
--- /dev/null
+++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
@@ -0,0 +1,109 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_VDSO_GETTIMEOFDAY_H
+#define __ASM_VDSO_GETTIMEOFDAY_H
+
+#ifndef __ASSEMBLY__
+
+#include <asm/time.h>
+#include <asm/unistd.h>
+#include <asm/vdso_datapage.h>
+#include <uapi/linux/time.h>
+
+#define VDSO_HAS_CLOCK_GETRES		1
+
+#define VDSO_HAS_TIME			1
+
+static __always_inline int do_syscall_2(const unsigned long _r0, const unsigned long _r3,
+					const unsigned long _r4)
+{
+	register long r0 asm("r0") = _r0;
+	register unsigned long r3 asm("r3") = _r3;
+	register unsigned long r4 asm("r4") = _r4;
+	register int ret asm ("r3");
+
+	asm volatile(
+		"       sc\n"
+		"	bns+	1f\n"
+		"	neg	%0, %0\n"
+		"1:\n"
+	: "+r" (ret), "+r" (r3), "+r" (r4), "+r" (r0)
+	:
+	: "memory", "r5", "r6", "r7", "r8", "r9", "r10", "r11", "r12", "cr0", "ctr");
+
+	return ret;
+}
+
+static __always_inline
+int gettimeofday_fallback(struct __kernel_old_timeval *_tv, struct timezone *_tz)
+{
+	return do_syscall_2(__NR_gettimeofday, (unsigned long)_tv, (unsigned long)_tz);
+}
+
+static __always_inline
+int clock_gettime_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
+{
+	return do_syscall_2(__NR_clock_gettime, _clkid, (unsigned long)_ts);
+}
+
+static __always_inline
+int clock_getres_fallback(clockid_t _clkid, struct __kernel_timespec *_ts)
+{
+	return do_syscall_2(__NR_clock_getres, _clkid, (unsigned long)_ts);
+}
+
+#ifdef CONFIG_VDSO32
+
+#define VDSO_HAS_32BIT_FALLBACK		1
+
+static __always_inline
+int clock_gettime32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
+{
+	return do_syscall_2(__NR_clock_gettime, _clkid, (unsigned long)_ts);
+}
+
+static __always_inline
+int clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
+{
+	return do_syscall_2(__NR_clock_getres, _clkid, (unsigned long)_ts);
+}
+#endif
+
+static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
+{
+	/*
+	 * clock_mode == 0 implies that vDSO are enabled otherwise
+	 * fallback on syscall.
+	 */
+	if (clock_mode != 0)
+		return U64_MAX;
+
+	return get_tb();
+}
+
+void *__get_datapage(void);
+
+static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
+{
+	struct vdso_arch_data *vdso_data = __get_datapage();
+
+	return vdso_data->data;
+}
+
+/*
+ * powerpc specific delta calculation.
+ *
+ * This variant removes the masking of the subtraction because the
+ * clocksource mask of all VDSO capable clocksources on powerpc is U64_MAX
+ * which would result in a pointless operation. The compiler cannot
+ * optimize it away as the mask comes from the vdso data and is not compile
+ * time constant.
+ */
+static __always_inline u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
+{
+	return (cycles - last) * mult;
+}
+#define vdso_calc_delta vdso_calc_delta
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __ASM_VDSO_GETTIMEOFDAY_H */
diff --git a/arch/powerpc/include/asm/vdso/vsyscall.h b/arch/powerpc/include/asm/vdso/vsyscall.h
new file mode 100644
index 000000000000..c56a030c0623
--- /dev/null
+++ b/arch/powerpc/include/asm/vdso/vsyscall.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __ASM_VDSO_VSYSCALL_H
+#define __ASM_VDSO_VSYSCALL_H
+
+#ifndef __ASSEMBLY__
+
+#include <linux/timekeeper_internal.h>
+#include <asm/vdso_datapage.h>
+
+/*
+ * Update the vDSO data page to keep in sync with kernel timekeeping.
+ */
+static __always_inline
+struct vdso_data *__arch_get_k_vdso_data(void)
+{
+	return vdso_data->data;
+}
+#define __arch_get_k_vdso_data __arch_get_k_vdso_data
+
+/* The asm-generic header needs to be included after the definitions above */
+#include <asm-generic/vdso/vsyscall.h>
+
+#endif /* !__ASSEMBLY__ */
+
+#endif /* __ASM_VDSO_VSYSCALL_H */
diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
index 40f13f3626d3..4d7965bf369e 100644
--- a/arch/powerpc/include/asm/vdso_datapage.h
+++ b/arch/powerpc/include/asm/vdso_datapage.h
@@ -36,6 +36,7 @@
 
 #include <linux/unistd.h>
 #include <linux/time.h>
+#include <vdso/datapage.h>
 
 #define SYSCALL_MAP_SIZE      ((NR_syscalls + 31) / 32)
 
@@ -45,7 +46,7 @@
 
 #ifdef CONFIG_PPC64
 
-struct vdso_data {
+struct vdso_arch_data {
 	__u8  eye_catcher[16];		/* Eyecatcher: SYSTEMCFG:PPC64	0x00 */
 	struct {			/* Systemcfg version numbers	     */
 		__u32 major;		/* Major number			0x10 */
@@ -59,13 +60,13 @@ struct vdso_data {
 	__u32 processor;		/* Processor type		0x1C */
 	__u64 processorCount;		/* # of physical processors	0x20 */
 	__u64 physicalMemorySize;	/* Size of real memory(B)	0x28 */
-	__u64 tb_orig_stamp;		/* Timebase at boot		0x30 */
+	__u64 tb_orig_stamp;		/* (NU) Timebase at boot	0x30 */
 	__u64 tb_ticks_per_sec;		/* Timebase tics / sec		0x38 */
-	__u64 tb_to_xs;			/* Inverse of TB to 2^20	0x40 */
-	__u64 stamp_xsec;		/*				0x48 */
-	__u64 tb_update_count;		/* Timebase atomicity ctr	0x50 */
-	__u32 tz_minuteswest;		/* Minutes west of Greenwich	0x58 */
-	__u32 tz_dsttime;		/* Type of dst correction	0x5C */
+	__u64 tb_to_xs;			/* (NU) Inverse of TB to 2^20	0x40 */
+	__u64 stamp_xsec;		/* (NU) 			0x48 */
+	__u64 tb_update_count;		/* (NU) Timebase atomicity ctr	0x50 */
+	__u32 tz_minuteswest;		/* (NU) Min. west of Greenwich	0x58 */
+	__u32 tz_dsttime;		/* (NU) Type of dst correction	0x5C */
 	__u32 dcache_size;		/* L1 d-cache size		0x60 */
 	__u32 dcache_line_size;		/* L1 d-cache line size		0x64 */
 	__u32 icache_size;		/* L1 i-cache size		0x68 */
@@ -78,14 +79,10 @@ struct vdso_data {
 	__u32 icache_block_size;		/* L1 i-cache block size     */
 	__u32 dcache_log_block_size;		/* L1 d-cache log block size */
 	__u32 icache_log_block_size;		/* L1 i-cache log block size */
-	__u32 stamp_sec_fraction;		/* fractional seconds of stamp_xtime */
-	__s32 wtom_clock_nsec;			/* Wall to monotonic clock nsec */
-	__s64 wtom_clock_sec;			/* Wall to monotonic clock sec */
-	__s64 stamp_xtime_sec;			/* xtime secs as at tb_orig_stamp */
-	__s64 stamp_xtime_nsec;			/* xtime nsecs as at tb_orig_stamp */
-	__u32 hrtimer_res;			/* hrtimer resolution */
    	__u32 syscall_map_64[SYSCALL_MAP_SIZE]; /* map of syscalls  */
    	__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
+
+	struct vdso_data data[CS_BASES];
 };
 
 #else /* CONFIG_PPC64 */
@@ -93,30 +90,20 @@ struct vdso_data {
 /*
  * And here is the simpler 32 bits version
  */
-struct vdso_data {
-	__u64 tb_orig_stamp;		/* Timebase at boot		0x30 */
+struct vdso_arch_data {
 	__u64 tb_ticks_per_sec;		/* Timebase tics / sec		0x38 */
-	__u64 tb_to_xs;			/* Inverse of TB to 2^20	0x40 */
-	__u64 stamp_xsec;		/*				0x48 */
-	__u32 tb_update_count;		/* Timebase atomicity ctr	0x50 */
-	__u32 tz_minuteswest;		/* Minutes west of Greenwich	0x58 */
-	__u32 tz_dsttime;		/* Type of dst correction	0x5C */
-	__s32 wtom_clock_sec;			/* Wall to monotonic clock */
-	__s32 wtom_clock_nsec;
-	__s32 stamp_xtime_sec;		/* xtime seconds as at tb_orig_stamp */
-	__s32 stamp_xtime_nsec;		/* xtime nsecs as at tb_orig_stamp */
-	__u32 stamp_sec_fraction;	/* fractional seconds of stamp_xtime */
-	__u32 hrtimer_res;		/* hrtimer resolution */
    	__u32 syscall_map_32[SYSCALL_MAP_SIZE]; /* map of syscalls */
 	__u32 dcache_block_size;	/* L1 d-cache block size     */
 	__u32 icache_block_size;	/* L1 i-cache block size     */
 	__u32 dcache_log_block_size;	/* L1 d-cache log block size */
 	__u32 icache_log_block_size;	/* L1 i-cache log block size */
+
+	struct vdso_data data[CS_BASES];
 };
 
 #endif /* CONFIG_PPC64 */
 
-extern struct vdso_data *vdso_data;
+extern struct vdso_arch_data *vdso_data;
 
 #endif /* __ASSEMBLY__ */
 
diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
index 3d47aec7becf..14ff4d159bc5 100644
--- a/arch/powerpc/kernel/asm-offsets.c
+++ b/arch/powerpc/kernel/asm-offsets.c
@@ -376,44 +376,16 @@ int main(void)
 #endif /* ! CONFIG_PPC64 */
 
 	/* datapage offsets for use by vdso */
-	OFFSET(CFG_TB_ORIG_STAMP, vdso_data, tb_orig_stamp);
-	OFFSET(CFG_TB_TICKS_PER_SEC, vdso_data, tb_ticks_per_sec);
-	OFFSET(CFG_TB_TO_XS, vdso_data, tb_to_xs);
-	OFFSET(CFG_TB_UPDATE_COUNT, vdso_data, tb_update_count);
-	OFFSET(CFG_TZ_MINUTEWEST, vdso_data, tz_minuteswest);
-	OFFSET(CFG_TZ_DSTTIME, vdso_data, tz_dsttime);
-	OFFSET(CFG_SYSCALL_MAP32, vdso_data, syscall_map_32);
-	OFFSET(WTOM_CLOCK_SEC, vdso_data, wtom_clock_sec);
-	OFFSET(WTOM_CLOCK_NSEC, vdso_data, wtom_clock_nsec);
-	OFFSET(STAMP_XTIME_SEC, vdso_data, stamp_xtime_sec);
-	OFFSET(STAMP_XTIME_NSEC, vdso_data, stamp_xtime_nsec);
-	OFFSET(STAMP_SEC_FRAC, vdso_data, stamp_sec_fraction);
-	OFFSET(CLOCK_HRTIMER_RES, vdso_data, hrtimer_res);
-	OFFSET(CFG_ICACHE_BLOCKSZ, vdso_data, icache_block_size);
-	OFFSET(CFG_DCACHE_BLOCKSZ, vdso_data, dcache_block_size);
-	OFFSET(CFG_ICACHE_LOGBLOCKSZ, vdso_data, icache_log_block_size);
-	OFFSET(CFG_DCACHE_LOGBLOCKSZ, vdso_data, dcache_log_block_size);
+	OFFSET(VDSO_DATA_OFFSET, vdso_arch_data, data);
+	OFFSET(CFG_TB_TICKS_PER_SEC, vdso_arch_data, tb_ticks_per_sec);
+	OFFSET(CFG_SYSCALL_MAP32, vdso_arch_data, syscall_map_32);
+	OFFSET(CFG_ICACHE_BLOCKSZ, vdso_arch_data, icache_block_size);
+	OFFSET(CFG_DCACHE_BLOCKSZ, vdso_arch_data, dcache_block_size);
+	OFFSET(CFG_ICACHE_LOGBLOCKSZ, vdso_arch_data, icache_log_block_size);
+	OFFSET(CFG_DCACHE_LOGBLOCKSZ, vdso_arch_data, dcache_log_block_size);
 #ifdef CONFIG_PPC64
-	OFFSET(CFG_SYSCALL_MAP64, vdso_data, syscall_map_64);
-	OFFSET(TVAL64_TV_SEC, __kernel_old_timeval, tv_sec);
-	OFFSET(TVAL64_TV_USEC, __kernel_old_timeval, tv_usec);
-#endif
-	OFFSET(TSPC64_TV_SEC, __kernel_timespec, tv_sec);
-	OFFSET(TSPC64_TV_NSEC, __kernel_timespec, tv_nsec);
-	OFFSET(TVAL32_TV_SEC, old_timeval32, tv_sec);
-	OFFSET(TVAL32_TV_USEC, old_timeval32, tv_usec);
-	OFFSET(TSPC32_TV_SEC, old_timespec32, tv_sec);
-	OFFSET(TSPC32_TV_NSEC, old_timespec32, tv_nsec);
-	/* timeval/timezone offsets for use by vdso */
-	OFFSET(TZONE_TZ_MINWEST, timezone, tz_minuteswest);
-	OFFSET(TZONE_TZ_DSTTIME, timezone, tz_dsttime);
-
-	/* Other bits used by the vdso */
-	DEFINE(CLOCK_REALTIME, CLOCK_REALTIME);
-	DEFINE(CLOCK_MONOTONIC, CLOCK_MONOTONIC);
-	DEFINE(CLOCK_REALTIME_COARSE, CLOCK_REALTIME_COARSE);
-	DEFINE(CLOCK_MONOTONIC_COARSE, CLOCK_MONOTONIC_COARSE);
-	DEFINE(NSEC_PER_SEC, NSEC_PER_SEC);
+	OFFSET(CFG_SYSCALL_MAP64, vdso_arch_data, syscall_map_64);
+#endif
 
 #ifdef CONFIG_BUG
 	DEFINE(BUG_ENTRY_SIZE, sizeof(struct bug_entry));
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index 1168e8b37e30..9075fe65424e 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -882,95 +882,6 @@ static notrace u64 timebase_read(struct clocksource *cs)
 	return (u64)get_tb();
 }
 
-
-void update_vsyscall(struct timekeeper *tk)
-{
-	struct timespec64 xt;
-	struct clocksource *clock = tk->tkr_mono.clock;
-	u32 mult = tk->tkr_mono.mult;
-	u32 shift = tk->tkr_mono.shift;
-	u64 cycle_last = tk->tkr_mono.cycle_last;
-	u64 new_tb_to_xs, new_stamp_xsec;
-	u64 frac_sec;
-
-	if (clock != &clocksource_timebase)
-		return;
-
-	xt.tv_sec = tk->xtime_sec;
-	xt.tv_nsec = (long)(tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift);
-
-	/* Make userspace gettimeofday spin until we're done. */
-	++vdso_data->tb_update_count;
-	smp_mb();
-
-	/*
-	 * This computes ((2^20 / 1e9) * mult) >> shift as a
-	 * 0.64 fixed-point fraction.
-	 * The computation in the else clause below won't overflow
-	 * (as long as the timebase frequency is >= 1.049 MHz)
-	 * but loses precision because we lose the low bits of the constant
-	 * in the shift.  Note that 19342813113834067 ~= 2^(20+64) / 1e9.
-	 * For a shift of 24 the error is about 0.5e-9, or about 0.5ns
-	 * over a second.  (Shift values are usually 22, 23 or 24.)
-	 * For high frequency clocks such as the 512MHz timebase clock
-	 * on POWER[6789], the mult value is small (e.g. 32768000)
-	 * and so we can shift the constant by 16 initially
-	 * (295147905179 ~= 2^(20+64-16) / 1e9) and then do the
-	 * remaining shifts after the multiplication, which gives a
-	 * more accurate result (e.g. with mult = 32768000, shift = 24,
-	 * the error is only about 1.2e-12, or 0.7ns over 10 minutes).
-	 */
-	if (mult <= 62500000 && clock->shift >= 16)
-		new_tb_to_xs = ((u64) mult * 295147905179ULL) >> (clock->shift - 16);
-	else
-		new_tb_to_xs = (u64) mult * (19342813113834067ULL >> clock->shift);
-
-	/*
-	 * Compute the fractional second in units of 2^-32 seconds.
-	 * The fractional second is tk->tkr_mono.xtime_nsec >> tk->tkr_mono.shift
-	 * in nanoseconds, so multiplying that by 2^32 / 1e9 gives
-	 * it in units of 2^-32 seconds.
-	 * We assume shift <= 32 because clocks_calc_mult_shift()
-	 * generates shift values in the range 0 - 32.
-	 */
-	frac_sec = tk->tkr_mono.xtime_nsec << (32 - shift);
-	do_div(frac_sec, NSEC_PER_SEC);
-
-	/*
-	 * Work out new stamp_xsec value for any legacy users of systemcfg.
-	 * stamp_xsec is in units of 2^-20 seconds.
-	 */
-	new_stamp_xsec = frac_sec >> 12;
-	new_stamp_xsec += tk->xtime_sec * XSEC_PER_SEC;
-
-	/*
-	 * tb_update_count is used to allow the userspace gettimeofday code
-	 * to assure itself that it sees a consistent view of the tb_to_xs and
-	 * stamp_xsec variables.  It reads the tb_update_count, then reads
-	 * tb_to_xs and stamp_xsec and then reads tb_update_count again.  If
-	 * the two values of tb_update_count match and are even then the
-	 * tb_to_xs and stamp_xsec values are consistent.  If not, then it
-	 * loops back and reads them again until this criteria is met.
-	 */
-	vdso_data->tb_orig_stamp = cycle_last;
-	vdso_data->stamp_xsec = new_stamp_xsec;
-	vdso_data->tb_to_xs = new_tb_to_xs;
-	vdso_data->wtom_clock_sec = tk->wall_to_monotonic.tv_sec;
-	vdso_data->wtom_clock_nsec = tk->wall_to_monotonic.tv_nsec;
-	vdso_data->stamp_xtime_sec = xt.tv_sec;
-	vdso_data->stamp_xtime_nsec = xt.tv_nsec;
-	vdso_data->stamp_sec_fraction = frac_sec;
-	vdso_data->hrtimer_res = hrtimer_resolution;
-	smp_wmb();
-	++(vdso_data->tb_update_count);
-}
-
-void update_vsyscall_tz(void)
-{
-	vdso_data->tz_minuteswest = sys_tz.tz_minuteswest;
-	vdso_data->tz_dsttime = sys_tz.tz_dsttime;
-}
-
 static void __init clocksource_init(void)
 {
 	struct clocksource *clock;
@@ -1140,7 +1051,6 @@ void __init time_init(void)
 		sys_tz.tz_dsttime = 0;
 	}
 
-	vdso_data->tb_update_count = 0;
 	vdso_data->tb_ticks_per_sec = tb_ticks_per_sec;
 
 	/* initialise and enable the large decrementer (if we have one) */
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index eae9ddaecbcf..16a44bffe698 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -17,6 +17,7 @@
 #include <linux/elf.h>
 #include <linux/security.h>
 #include <linux/memblock.h>
+#include <vdso/datapage.h>
 
 #include <asm/pgtable.h>
 #include <asm/processor.h>
@@ -71,10 +72,10 @@ static int vdso_ready;
  * with it, it will become dynamically allocated
  */
 static union {
-	struct vdso_data	data;
+	struct vdso_arch_data	data;
 	u8			page[PAGE_SIZE];
 } vdso_data_store __page_aligned_data;
-struct vdso_data *vdso_data = &vdso_data_store.data;
+struct vdso_arch_data *vdso_data = &vdso_data_store.data;
 
 /* Format of the patch table */
 struct vdso_patch_def
diff --git a/arch/powerpc/kernel/vdso32/Makefile b/arch/powerpc/kernel/vdso32/Makefile
index 738d52105392..b82f51a24747 100644
--- a/arch/powerpc/kernel/vdso32/Makefile
+++ b/arch/powerpc/kernel/vdso32/Makefile
@@ -2,11 +2,23 @@
 
 # List of files in the vdso, has to be asm only for now
 
+ARCH_REL_TYPE_ABS := R_PPC_JUMP_SLOT|R_PPC_GLOB_DAT|R_PPC_ADDR32|R_PPC_ADDR24|R_PPC_ADDR16|R_PPC_ADDR16_LO|R_PPC_ADDR16_HI|R_PPC_ADDR16_HA|R_PPC_ADDR14|R_PPC_ADDR14_BRTAKEN|R_PPC_ADDR14_BRNTAKEN
+include $(srctree)/lib/vdso/Makefile
+
 obj-vdso32-$(CONFIG_PPC64) = getcpu.o
 obj-vdso32-$(CONFIG_PPC32) = gettimeofday.o
 obj-vdso32 = sigtramp.o datapage.o cacheflush.o note.o \
 		$(obj-vdso32-y)
 
+ifneq ($(c-gettimeofday-y),)
+  CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
+  CFLAGS_vgettimeofday.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
+  CFLAGS_vgettimeofday.o += $(call cc-option, -fno-stack-protector)
+  CFLAGS_vgettimeofday.o += -DDISABLE_BRANCH_PROFILING
+  CFLAGS_vgettimeofday.o += -ffreestanding
+  CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE)
+endif
+
 # Build rules
 
 ifdef CROSS32_COMPILE
@@ -26,6 +38,7 @@ obj-vdso32 := $(addprefix $(obj)/, $(obj-vdso32))
 GCOV_PROFILE := n
 KCOV_INSTRUMENT := n
 UBSAN_SANITIZE := n
+KASAN_SANITIZE := n
 
 ccflags-y := -shared -fno-common -fno-builtin -nostdlib \
 	-Wl,-soname=linux-vdso32.so.1 -Wl,--hash-style=both
@@ -39,8 +52,12 @@ CPPFLAGS_vdso32.lds += -P -C -Upowerpc
 $(obj)/vdso32_wrapper.o : $(obj)/vdso32.so
 
 # link rule for the .so file, .lds has to be first
+ifdef CONFIG_PPC32
+$(obj)/vdso32.so.dbg: $(src)/vdso32.lds $(obj-vdso32) $(obj)/vgettimeofday.o FORCE
+else
 $(obj)/vdso32.so.dbg: $(src)/vdso32.lds $(obj-vdso32) FORCE
-	$(call if_changed,vdso32ld)
+endif
+	$(call if_changed,vdso32ld_and_check)
 
 # strip rule for the .so file
 $(obj)/%.so: OBJCOPYFLAGS := -S
@@ -50,12 +67,16 @@ $(obj)/%.so: $(obj)/%.so.dbg FORCE
 # assembly rules for the .S files
 $(obj-vdso32): %.o: %.S FORCE
 	$(call if_changed_dep,vdso32as)
+$(obj)/vgettimeofday.o: %.o: %.c FORCE
+	$(call if_changed_dep,vdso32cc)
 
 # actual build commands
-quiet_cmd_vdso32ld = VDSO32L $@
-      cmd_vdso32ld = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^)
+quiet_cmd_vdso32ld_and_check = VDSO32L $@
+      cmd_vdso32ld_and_check = $(VDSOCC) $(c_flags) $(CC32FLAGS) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) ; $(cmd_vdso_check)
 quiet_cmd_vdso32as = VDSO32A $@
       cmd_vdso32as = $(VDSOCC) $(a_flags) $(CC32FLAGS) -c -o $@ $<
+quiet_cmd_vdso32cc = VDSO32A $@
+      cmd_vdso32cc = $(VDSOCC) $(c_flags) $(CC32FLAGS) -c -o $@ $<
 
 # install commands for the unstripped file
 quiet_cmd_vdso_install = INSTALL $@
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
index 3306672f57a9..ba0bd64b3da3 100644
--- a/arch/powerpc/kernel/vdso32/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
@@ -12,14 +12,24 @@
 #include <asm/asm-offsets.h>
 #include <asm/unistd.h>
 
-/* Offset for the low 32-bit part of a field of long type */
-#ifdef CONFIG_PPC64
-#define LOPART	4
-#else
-#define LOPART	0
-#endif
-
 	.text
+
+.macro cvdso_call funct
+	stwu	r1, -16(r1)
+	mflr	r0
+	stw	r0, 20(r1)
+	bl	\funct
+	lwz	r0, 20(r1)
+	cmpwi	r3, 0
+	mtlr	r0
+	addi	r1, r1, 16
+	crclr	so
+	beqlr+
+	crset	so
+	neg	r3, r3
+	blr
+.endm
+
 /*
  * Exact prototype of gettimeofday
  *
@@ -28,32 +38,7 @@
  */
 V_FUNCTION_BEGIN(__kernel_gettimeofday)
   .cfi_startproc
-	mflr	r12
-  .cfi_register lr,r12
-
-	mr	r10,r3			/* r10 saves tv */
-	mr	r11,r4			/* r11 saves tz */
-	bl	__get_datapage@local	/* get data page */
-	mr	r9, r3			/* datapage ptr in r9 */
-	cmplwi	r10,0			/* check if tv is NULL */
-	beq	3f
-	lis	r7,1000000@ha		/* load up USEC_PER_SEC */
-	addi	r7,r7,1000000@l		/* so we get microseconds in r4 */
-	bl	__do_get_tspec@local	/* get sec/usec from tb & kernel */
-	stw	r3,TVAL32_TV_SEC(r10)
-	stw	r4,TVAL32_TV_USEC(r10)
-
-3:	cmplwi	r11,0			/* check if tz is NULL */
-	beq	1f
-	lwz	r4,CFG_TZ_MINUTEWEST(r9)/* fill tz */
-	lwz	r5,CFG_TZ_DSTTIME(r9)
-	stw	r4,TZONE_TZ_MINWEST(r11)
-	stw	r5,TZONE_TZ_DSTTIME(r11)
-
-1:	mtlr	r12
-	crclr	cr0*4+so
-	li	r3,0
-	blr
+	cvdso_call __c_kernel_gettimeofday
   .cfi_endproc
 V_FUNCTION_END(__kernel_gettimeofday)
 
@@ -65,77 +50,7 @@ V_FUNCTION_END(__kernel_gettimeofday)
  */
 V_FUNCTION_BEGIN(__kernel_clock_gettime)
   .cfi_startproc
-	/* Check for supported clock IDs */
-	cmpli	cr0,r3,CLOCK_REALTIME
-	cmpli	cr1,r3,CLOCK_MONOTONIC
-	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
-	bne	cr0,99f
-
-	mflr	r12			/* r12 saves lr */
-  .cfi_register lr,r12
-	mr	r11,r4			/* r11 saves tp */
-	bl	__get_datapage@local	/* get data page */
-	mr	r9,r3			/* datapage ptr in r9 */
-	lis	r7,NSEC_PER_SEC@h	/* want nanoseconds */
-	ori	r7,r7,NSEC_PER_SEC@l
-50:	bl	__do_get_tspec@local	/* get sec/nsec from tb & kernel */
-	bne	cr1,80f			/* not monotonic -> all done */
-
-	/*
-	 * CLOCK_MONOTONIC
-	 */
-
-	/* now we must fixup using wall to monotonic. We need to snapshot
-	 * that value and do the counter trick again. Fortunately, we still
-	 * have the counter value in r8 that was returned by __do_get_xsec.
-	 * At this point, r3,r4 contain our sec/nsec values, r5 and r6
-	 * can be used, r7 contains NSEC_PER_SEC.
-	 */
-
-	lwz	r5,(WTOM_CLOCK_SEC+LOPART)(r9)
-	lwz	r6,WTOM_CLOCK_NSEC(r9)
-
-	/* We now have our offset in r5,r6. We create a fake dependency
-	 * on that value and re-check the counter
-	 */
-	or	r0,r6,r5
-	xor	r0,r0,r0
-	add	r9,r9,r0
-	lwz	r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
-        cmpl    cr0,r8,r0		/* check if updated */
-	bne-	50b
-
-	/* Calculate and store result. Note that this mimics the C code,
-	 * which may cause funny results if nsec goes negative... is that
-	 * possible at all ?
-	 */
-	add	r3,r3,r5
-	add	r4,r4,r6
-	cmpw	cr0,r4,r7
-	cmpwi	cr1,r4,0
-	blt	1f
-	subf	r4,r7,r4
-	addi	r3,r3,1
-1:	bge	cr1,80f
-	addi	r3,r3,-1
-	add	r4,r4,r7
-
-80:	stw	r3,TSPC32_TV_SEC(r11)
-	stw	r4,TSPC32_TV_NSEC(r11)
-
-	mtlr	r12
-	crclr	cr0*4+so
-	li	r3,0
-	blr
-
-	/*
-	 * syscall fallback
-	 */
-99:
-	li	r0,__NR_clock_gettime
-  .cfi_restore lr
-	sc
-	blr
+	cvdso_call __c_kernel_clock_gettime
   .cfi_endproc
 V_FUNCTION_END(__kernel_clock_gettime)
 
@@ -148,32 +63,7 @@ V_FUNCTION_END(__kernel_clock_gettime)
  */
 V_FUNCTION_BEGIN(__kernel_clock_getres)
   .cfi_startproc
-	/* Check for supported clock IDs */
-	cmpwi	cr0,r3,CLOCK_REALTIME
-	cmpwi	cr1,r3,CLOCK_MONOTONIC
-	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
-	bne	cr0,99f
-
-	mflr	r12
-  .cfi_register lr,r12
-	bl	__get_datapage@local	/* get data page */
-	lwz	r5, CLOCK_HRTIMER_RES(r3)
-	mtlr	r12
-	li	r3,0
-	cmpli	cr0,r4,0
-	crclr	cr0*4+so
-	beqlr
-	stw	r3,TSPC32_TV_SEC(r4)
-	stw	r5,TSPC32_TV_NSEC(r4)
-	blr
-
-	/*
-	 * syscall fallback
-	 */
-99:
-	li	r0,__NR_clock_getres
-	sc
-	blr
+	cvdso_call __c_kernel_clock_getres
   .cfi_endproc
 V_FUNCTION_END(__kernel_clock_getres)
 
@@ -186,105 +76,14 @@ V_FUNCTION_END(__kernel_clock_getres)
  */
 V_FUNCTION_BEGIN(__kernel_time)
   .cfi_startproc
-	mflr	r12
-  .cfi_register lr,r12
-
-	mr	r11,r3			/* r11 holds t */
-	bl	__get_datapage@local
-	mr	r9, r3			/* datapage ptr in r9 */
-
-	lwz	r3,STAMP_XTIME_SEC+LOPART(r9)
-
-	cmplwi	r11,0			/* check if t is NULL */
-	beq	2f
-	stw	r3,0(r11)		/* store result at *t */
-2:	mtlr	r12
+	stwu	r1, -16(r1)
+	mflr	r0
+	stw	r0, 20(r1)
+	bl	__c_kernel_time
+	lwz	r0, 20(r1)
 	crclr	cr0*4+so
+	mtlr	r0
+	addi	r1, r1, 16
 	blr
   .cfi_endproc
 V_FUNCTION_END(__kernel_time)
-
-/*
- * This is the core of clock_gettime() and gettimeofday(),
- * it returns the current time in r3 (seconds) and r4.
- * On entry, r7 gives the resolution of r4, either USEC_PER_SEC
- * or NSEC_PER_SEC, giving r4 in microseconds or nanoseconds.
- * It expects the datapage ptr in r9 and doesn't clobber it.
- * It clobbers r0, r5 and r6.
- * On return, r8 contains the counter value that can be reused.
- * This clobbers cr0 but not any other cr field.
- */
-__do_get_tspec:
-  .cfi_startproc
-	/* Check for update count & load values. We use the low
-	 * order 32 bits of the update count
-	 */
-1:	lwz	r8,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
-	andi.	r0,r8,1			/* pending update ? loop */
-	bne-	1b
-	xor	r0,r8,r8		/* create dependency */
-	add	r9,r9,r0
-
-	/* Load orig stamp (offset to TB) */
-	lwz	r5,CFG_TB_ORIG_STAMP(r9)
-	lwz	r6,(CFG_TB_ORIG_STAMP+4)(r9)
-
-	/* Get a stable TB value */
-2:	MFTBU(r3)
-	MFTBL(r4)
-	MFTBU(r0)
-	cmplw	cr0,r3,r0
-	bne-	2b
-
-	/* Subtract tb orig stamp and shift left 12 bits.
-	 */
-	subfc	r4,r6,r4
-	subfe	r0,r5,r3
-	slwi	r0,r0,12
-	rlwimi.	r0,r4,12,20,31
-	slwi	r4,r4,12
-
-	/*
-	 * Load scale factor & do multiplication.
-	 * We only use the high 32 bits of the tb_to_xs value.
-	 * Even with a 1GHz timebase clock, the high 32 bits of
-	 * tb_to_xs will be at least 4 million, so the error from
-	 * ignoring the low 32 bits will be no more than 0.25ppm.
-	 * The error will just make the clock run very very slightly
-	 * slow until the next time the kernel updates the VDSO data,
-	 * at which point the clock will catch up to the kernel's value,
-	 * so there is no long-term error accumulation.
-	 */
-	lwz	r5,CFG_TB_TO_XS(r9)	/* load values */
-	mulhwu	r4,r4,r5
-	li	r3,0
-
-	beq+	4f			/* skip high part computation if 0 */
-	mulhwu	r3,r0,r5
-	mullw	r5,r0,r5
-	addc	r4,r4,r5
-	addze	r3,r3
-4:
-	/* At this point, we have seconds since the xtime stamp
-	 * as a 32.32 fixed-point number in r3 and r4.
-	 * Load & add the xtime stamp.
-	 */
-	lwz	r5,STAMP_XTIME_SEC+LOPART(r9)
-	lwz	r6,STAMP_SEC_FRAC(r9)
-	addc	r4,r4,r6
-	adde	r3,r3,r5
-
-	/* We create a fake dependency on the result in r3/r4
-	 * and re-check the counter
-	 */
-	or	r6,r4,r3
-	xor	r0,r6,r6
-	add	r9,r9,r0
-	lwz	r0,(CFG_TB_UPDATE_COUNT+LOPART)(r9)
-        cmplw	cr0,r8,r0		/* check if updated */
-	bne-	1b
-
-	mulhwu	r4,r4,r7		/* convert to micro or nanoseconds */
-
-	blr
-  .cfi_endproc
diff --git a/arch/powerpc/kernel/vdso32/vgettimeofday.c b/arch/powerpc/kernel/vdso32/vgettimeofday.c
new file mode 100644
index 000000000000..4ed1bf2ae30e
--- /dev/null
+++ b/arch/powerpc/kernel/vdso32/vgettimeofday.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Powerpc userspace implementations of gettimeofday() and similar.
+ */
+#include <linux/time.h>
+#include <linux/types.h>
+
+int __c_kernel_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
+{
+	return __cvdso_clock_gettime32(clock, ts);
+}
+
+int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
+{
+	return __cvdso_gettimeofday(tv, tz);
+}
+
+int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res)
+{
+	return __cvdso_clock_getres_time32(clock_id, res);
+}
+
+time_t __c_kernel_time(time_t *time)
+{
+	return __cvdso_time(time);
+}
diff --git a/arch/powerpc/kernel/vdso64/Makefile b/arch/powerpc/kernel/vdso64/Makefile
index 32ebb3522ea1..0d80069233e0 100644
--- a/arch/powerpc/kernel/vdso64/Makefile
+++ b/arch/powerpc/kernel/vdso64/Makefile
@@ -1,8 +1,20 @@
 # SPDX-License-Identifier: GPL-2.0
 # List of files in the vdso, has to be asm only for now
 
+ARCH_REL_TYPE_ABS := R_PPC_JUMP_SLOT|R_PPC_GLOB_DAT|R_PPC_ADDR32|R_PPC_ADDR24|R_PPC_ADDR16|R_PPC_ADDR16_LO|R_PPC_ADDR16_HI|R_PPC_ADDR16_HA|R_PPC_ADDR14|R_PPC_ADDR14_BRTAKEN|R_PPC_ADDR14_BRNTAKEN
+include $(srctree)/lib/vdso/Makefile
+
 obj-vdso64 = sigtramp.o gettimeofday.o datapage.o cacheflush.o note.o getcpu.o
 
+ifneq ($(c-gettimeofday-y),)
+  CFLAGS_vgettimeofday.o += -include $(c-gettimeofday-y)
+  CFLAGS_vgettimeofday.o += $(DISABLE_LATENT_ENTROPY_PLUGIN)
+  CFLAGS_vgettimeofday.o += $(call cc-option, -fno-stack-protector)
+  CFLAGS_vgettimeofday.o += -DDISABLE_BRANCH_PROFILING
+  CFLAGS_vgettimeofday.o += -ffreestanding
+  CFLAGS_REMOVE_vgettimeofday.o = $(CC_FLAGS_FTRACE)
+endif
+
 # Build rules
 
 targets := $(obj-vdso64) vdso64.so vdso64.so.dbg
@@ -11,6 +23,7 @@ obj-vdso64 := $(addprefix $(obj)/, $(obj-vdso64))
 GCOV_PROFILE := n
 KCOV_INSTRUMENT := n
 UBSAN_SANITIZE := n
+KASAN_SANITIZE := n
 
 ccflags-y := -shared -fno-common -fno-builtin -nostdlib \
 	-Wl,-soname=linux-vdso64.so.1 -Wl,--hash-style=both
@@ -20,12 +33,14 @@ obj-y += vdso64_wrapper.o
 extra-y += vdso64.lds
 CPPFLAGS_vdso64.lds += -P -C -U$(ARCH)
 
+$(obj)/vgettimeofday.o: %.o: %.c FORCE
+
 # Force dependency (incbin is bad)
 $(obj)/vdso64_wrapper.o : $(obj)/vdso64.so
 
 # link rule for the .so file, .lds has to be first
-$(obj)/vdso64.so.dbg: $(src)/vdso64.lds $(obj-vdso64) FORCE
-	$(call if_changed,vdso64ld)
+$(obj)/vdso64.so.dbg: $(src)/vdso64.lds $(obj-vdso64) $(obj)/vgettimeofday.o FORCE
+	$(call if_changed,vdso64ld_and_check)
 
 # strip rule for the .so file
 $(obj)/%.so: OBJCOPYFLAGS := -S
@@ -33,8 +48,8 @@ $(obj)/%.so: $(obj)/%.so.dbg FORCE
 	$(call if_changed,objcopy)
 
 # actual build commands
-quiet_cmd_vdso64ld = VDSO64L $@
-      cmd_vdso64ld = $(CC) $(c_flags) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^)
+quiet_cmd_vdso64ld_and_check = VDSO64L $@
+      cmd_vdso64ld_and_check = $(CC) $(c_flags) -o $@ -Wl,-T$(filter %.lds,$^) $(filter %.o,$^) ; $(cmd_vdso_check)
 
 # install commands for the unstripped file
 quiet_cmd_vdso_install = INSTALL $@
diff --git a/arch/powerpc/kernel/vdso64/datapage.S b/arch/powerpc/kernel/vdso64/datapage.S
index dc84f5ae3802..4808ce9eeb3d 100644
--- a/arch/powerpc/kernel/vdso64/datapage.S
+++ b/arch/powerpc/kernel/vdso64/datapage.S
@@ -16,7 +16,7 @@
 __kernel_datapage_offset:
 	.long	0
 
-V_FUNCTION_BEGIN(__get_datapage)
+_GLOBAL(__get_datapage)
   .cfi_startproc
 	/* We don't want that exposed or overridable as we want other objects
 	 * to be able to bl directly to here
@@ -37,7 +37,6 @@ data_page_branch:
 	add	r3,r0,r3
 	blr
   .cfi_endproc
-V_FUNCTION_END(__get_datapage)
 
 /*
  * void *__kernel_get_syscall_map(unsigned int *syscall_count) ;
diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
index 1c9a04703250..22f4f1f73bbc 100644
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -13,6 +13,23 @@
 #include <asm/unistd.h>
 
 	.text
+
+.macro cvdso_call funct
+	mflr	r0
+	std	r0, 16(r1)
+	stdu	r1, -128(r1)
+	bl	\funct
+	addi	r1, r1, 128
+	ld	r0, 16(r1)
+	cmpwi	r3, 0
+	mtlr	r0
+	crclr	so
+	beqlr+
+	crset	so
+	neg	r3, r3
+	blr
+.endm
+
 /*
  * Exact prototype of gettimeofday
  *
@@ -21,29 +38,7 @@
  */
 V_FUNCTION_BEGIN(__kernel_gettimeofday)
   .cfi_startproc
-	mflr	r12
-  .cfi_register lr,r12
-
-	mr	r11,r3			/* r11 holds tv */
-	mr	r10,r4			/* r10 holds tz */
-	bl	V_LOCAL_FUNC(__get_datapage)	/* get data page */
-	cmpldi	r11,0			/* check if tv is NULL */
-	beq	2f
-	lis	r7,1000000@ha		/* load up USEC_PER_SEC */
-	addi	r7,r7,1000000@l
-	bl	V_LOCAL_FUNC(__do_get_tspec) /* get sec/us from tb & kernel */
-	std	r4,TVAL64_TV_SEC(r11)	/* store sec in tv */
-	std	r5,TVAL64_TV_USEC(r11)	/* store usec in tv */
-2:	cmpldi	r10,0			/* check if tz is NULL */
-	beq	1f
-	lwz	r4,CFG_TZ_MINUTEWEST(r3)/* fill tz */
-	lwz	r5,CFG_TZ_DSTTIME(r3)
-	stw	r4,TZONE_TZ_MINWEST(r10)
-	stw	r5,TZONE_TZ_DSTTIME(r10)
-1:	mtlr	r12
-	crclr	cr0*4+so
-	li	r3,0			/* always success */
-	blr
+	cvdso_call __c_kernel_gettimeofday
   .cfi_endproc
 V_FUNCTION_END(__kernel_gettimeofday)
 
@@ -56,118 +51,7 @@ V_FUNCTION_END(__kernel_gettimeofday)
  */
 V_FUNCTION_BEGIN(__kernel_clock_gettime)
   .cfi_startproc
-	/* Check for supported clock IDs */
-	cmpwi	cr0,r3,CLOCK_REALTIME
-	cmpwi	cr1,r3,CLOCK_MONOTONIC
-	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
-
-	cmpwi	cr5,r3,CLOCK_REALTIME_COARSE
-	cmpwi	cr6,r3,CLOCK_MONOTONIC_COARSE
-	cror	cr5*4+eq,cr5*4+eq,cr6*4+eq
-
-	cror	cr0*4+eq,cr0*4+eq,cr5*4+eq
-	bne	cr0,99f
-
-	mflr	r12			/* r12 saves lr */
-  .cfi_register lr,r12
-	mr	r11,r4			/* r11 saves tp */
-	bl	V_LOCAL_FUNC(__get_datapage)	/* get data page */
-	lis	r7,NSEC_PER_SEC@h	/* want nanoseconds */
-	ori	r7,r7,NSEC_PER_SEC@l
-	beq	cr5,70f
-50:	bl	V_LOCAL_FUNC(__do_get_tspec)	/* get time from tb & kernel */
-	bne	cr1,80f			/* if not monotonic, all done */
-
-	/*
-	 * CLOCK_MONOTONIC
-	 */
-
-	/* now we must fixup using wall to monotonic. We need to snapshot
-	 * that value and do the counter trick again. Fortunately, we still
-	 * have the counter value in r8 that was returned by __do_get_tspec.
-	 * At this point, r4,r5 contain our sec/nsec values.
-	 */
-
-	ld	r6,WTOM_CLOCK_SEC(r3)
-	lwa	r9,WTOM_CLOCK_NSEC(r3)
-
-	/* We now have our result in r6,r9. We create a fake dependency
-	 * on that result and re-check the counter
-	 */
-	or	r0,r6,r9
-	xor	r0,r0,r0
-	add	r3,r3,r0
-	ld	r0,CFG_TB_UPDATE_COUNT(r3)
-        cmpld   cr0,r0,r8		/* check if updated */
-	bne-	50b
-	b	78f
-
-	/*
-	 * For coarse clocks we get data directly from the vdso data page, so
-	 * we don't need to call __do_get_tspec, but we still need to do the
-	 * counter trick.
-	 */
-70:	ld      r8,CFG_TB_UPDATE_COUNT(r3)
-	andi.   r0,r8,1                 /* pending update ? loop */
-	bne-    70b
-	add     r3,r3,r0		/* r0 is already 0 */
-
-	/*
-	 * CLOCK_REALTIME_COARSE, below values are needed for MONOTONIC_COARSE
-	 * too
-	 */
-	ld      r4,STAMP_XTIME_SEC(r3)
-	ld      r5,STAMP_XTIME_NSEC(r3)
-	bne     cr6,75f
-
-	/* CLOCK_MONOTONIC_COARSE */
-	ld	r6,WTOM_CLOCK_SEC(r3)
-	lwa     r9,WTOM_CLOCK_NSEC(r3)
-
-	/* check if counter has updated */
-	or      r0,r6,r9
-75:	or	r0,r0,r4
-	or	r0,r0,r5
-	xor     r0,r0,r0
-	add     r3,r3,r0
-	ld      r0,CFG_TB_UPDATE_COUNT(r3)
-	cmpld   cr0,r0,r8               /* check if updated */
-	bne-    70b
-
-	/* Counter has not updated, so continue calculating proper values for
-	 * sec and nsec if monotonic coarse, or just return with the proper
-	 * values for realtime.
-	 */
-	bne     cr6,80f
-
-	/* Add wall->monotonic offset and check for overflow or underflow */
-78:	add     r4,r4,r6
-	add     r5,r5,r9
-	cmpd    cr0,r5,r7
-	cmpdi   cr1,r5,0
-	blt     79f
-	subf    r5,r7,r5
-	addi    r4,r4,1
-79:	bge     cr1,80f
-	addi    r4,r4,-1
-	add     r5,r5,r7
-
-80:	std	r4,TSPC64_TV_SEC(r11)
-	std	r5,TSPC64_TV_NSEC(r11)
-
-	mtlr	r12
-	crclr	cr0*4+so
-	li	r3,0
-	blr
-
-	/*
-	 * syscall fallback
-	 */
-99:
-	li	r0,__NR_clock_gettime
-  .cfi_restore lr
-	sc
-	blr
+	cvdso_call __c_kernel_clock_gettime
   .cfi_endproc
 V_FUNCTION_END(__kernel_clock_gettime)
 
@@ -180,32 +64,7 @@ V_FUNCTION_END(__kernel_clock_gettime)
  */
 V_FUNCTION_BEGIN(__kernel_clock_getres)
   .cfi_startproc
-	/* Check for supported clock IDs */
-	cmpwi	cr0,r3,CLOCK_REALTIME
-	cmpwi	cr1,r3,CLOCK_MONOTONIC
-	cror	cr0*4+eq,cr0*4+eq,cr1*4+eq
-	bne	cr0,99f
-
-	mflr	r12
-  .cfi_register lr,r12
-	bl	V_LOCAL_FUNC(__get_datapage)
-	lwz	r5, CLOCK_HRTIMER_RES(r3)
-	mtlr	r12
-	li	r3,0
-	cmpldi	cr0,r4,0
-	crclr	cr0*4+so
-	beqlr
-	std	r3,TSPC64_TV_SEC(r4)
-	std	r5,TSPC64_TV_NSEC(r4)
-	blr
-
-	/*
-	 * syscall fallback
-	 */
-99:
-	li	r0,__NR_clock_getres
-	sc
-	blr
+	cvdso_call __c_kernel_clock_getres
   .cfi_endproc
 V_FUNCTION_END(__kernel_clock_getres)
 
@@ -217,73 +76,14 @@ V_FUNCTION_END(__kernel_clock_getres)
  */
 V_FUNCTION_BEGIN(__kernel_time)
   .cfi_startproc
-	mflr	r12
-  .cfi_register lr,r12
-
-	mr	r11,r3			/* r11 holds t */
-	bl	V_LOCAL_FUNC(__get_datapage)
-
-	ld	r4,STAMP_XTIME_SEC(r3)
-
-	cmpldi	r11,0			/* check if t is NULL */
-	beq	2f
-	std	r4,0(r11)		/* store result at *t */
-2:	mtlr	r12
+	mflr	r0
+	std	r0, 16(r1)
+	stdu	r1, -128(r1)
+	bl	__c_kernel_time
+	addi	r1, r1, 128
+	ld	r0, 16(r1)
 	crclr	cr0*4+so
-	mr	r3,r4
+	mtlr	r0
 	blr
   .cfi_endproc
 V_FUNCTION_END(__kernel_time)
-
-
-/*
- * This is the core of clock_gettime() and gettimeofday(),
- * it returns the current time in r4 (seconds) and r5.
- * On entry, r7 gives the resolution of r5, either USEC_PER_SEC
- * or NSEC_PER_SEC, giving r5 in microseconds or nanoseconds.
- * It expects the datapage ptr in r3 and doesn't clobber it.
- * It clobbers r0, r6 and r9.
- * On return, r8 contains the counter value that can be reused.
- * This clobbers cr0 but not any other cr field.
- */
-V_FUNCTION_BEGIN(__do_get_tspec)
-  .cfi_startproc
-	/* check for update count & load values */
-1:	ld	r8,CFG_TB_UPDATE_COUNT(r3)
-	andi.	r0,r8,1			/* pending update ? loop */
-	bne-	1b
-	xor	r0,r8,r8		/* create dependency */
-	add	r3,r3,r0
-
-	/* Get TB & offset it. We use the MFTB macro which will generate
-	 * workaround code for Cell.
-	 */
-	MFTB(r6)
-	ld	r9,CFG_TB_ORIG_STAMP(r3)
-	subf	r6,r9,r6
-
-	/* Scale result */
-	ld	r5,CFG_TB_TO_XS(r3)
-	sldi	r6,r6,12		/* compute time since stamp_xtime */
-	mulhdu	r6,r6,r5		/* in units of 2^-32 seconds */
-
-	/* Add stamp since epoch */
-	ld	r4,STAMP_XTIME_SEC(r3)
-	lwz	r5,STAMP_SEC_FRAC(r3)
-	or	r0,r4,r5
-	or	r0,r0,r6
-	xor	r0,r0,r0
-	add	r3,r3,r0
-	ld	r0,CFG_TB_UPDATE_COUNT(r3)
-	cmpld   r0,r8			/* check if updated */
-	bne-	1b			/* reload if so */
-
-	/* convert to seconds & nanoseconds and add to stamp */
-	add	r6,r6,r5		/* add on fractional seconds of xtime */
-	mulhwu	r5,r6,r7		/* compute micro or nanoseconds and */
-	srdi	r6,r6,32		/* seconds since stamp_xtime */
-	clrldi	r5,r5,32
-	add	r4,r4,r6
-	blr
-  .cfi_endproc
-V_FUNCTION_END(__do_get_tspec)
diff --git a/arch/powerpc/kernel/vdso64/vgettimeofday.c b/arch/powerpc/kernel/vdso64/vgettimeofday.c
new file mode 100644
index 000000000000..407c6a7ed4e2
--- /dev/null
+++ b/arch/powerpc/kernel/vdso64/vgettimeofday.c
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Powerpc userspace implementations of gettimeofday() and similar.
+ */
+#include <linux/time.h>
+#include <linux/types.h>
+
+int __c_kernel_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
+{
+	return __cvdso_clock_gettime(clock, ts);
+}
+
+int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
+{
+	return __cvdso_gettimeofday(tv, tz);
+}
+
+int __c_kernel_clock_getres(clockid_t clock_id, struct __kernel_timespec *res)
+{
+	return __cvdso_clock_getres(clock_id, res);
+}
+
+time_t __c_kernel_time(time_t *time)
+{
+	return __cvdso_time(time);
+}
-- 
2.13.3




^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 03/12] lib: vdso: mark __cvdso_clock_getres() as static
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 01/12] powerpc/64: Don't provide time functions in compat VDSO32 Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 02/12] powerpc/vdso: Switch VDSO to generic C implementation Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 04/12] lib: vdso: inline do_hres() and do_coarse() Christophe Leroy
                   ` (8 subsequent siblings)
  11 siblings, 0 replies; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

When __cvdso_clock_getres() became __cvdso_clock_getres_common()
and a new __cvdso_clock_getres() was added, static qualifier was
forgotten.

This change allows the compiler to inline __cvdso_clock_getres_common(),
and the performance improvement is significant:

Before:
clock-getres-realtime-coarse:    vdso: 984 nsec/call
clock-getres-realtime:    vdso: 922 nsec/call
clock-getres-monotonic-raw:    vdso: 968 nsec/call

After:
clock-getres-realtime-coarse:    vdso: 753 nsec/call
clock-getres-realtime:    vdso: 691 nsec/call
clock-getres-monotonic-raw:    vdso: 737 nsec/call

Fixes: 502a590a170b ("lib/vdso: Move fallback invocation to the callers")
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 lib/vdso/gettimeofday.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 9ecfd3b547ba..42bd8ab955fa 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -221,6 +221,7 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
 	return 0;
 }
 
+static __maybe_unused
 int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
 {
 	int ret = __cvdso_clock_getres_common(clock, res);
-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 04/12] lib: vdso: inline do_hres() and do_coarse()
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
                   ` (2 preceding siblings ...)
  2020-01-13 17:08 ` [RFC PATCH v3 03/12] lib: vdso: mark __cvdso_clock_getres() as static Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 05/12] lib: vdso: Avoid duplication in __cvdso_clock_getres() Christophe Leroy
                   ` (7 subsequent siblings)
  11 siblings, 0 replies; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

do_hres() is called from several places, so GCC doesn't inline
it at first.

do_hres() takes a struct __kernel_timespec * parameter for
passing the result. In the 32 bits case, this parameter corresponds
to a local var in the caller. In order to provide a pointer
to this structure, the caller has to put it in its stack and
do_hres() has to write the result in the stack. This is suboptimal,
especially on RISC processor like powerpc.

By making GCC inline the function, the struct __kernel_timespec
remains a local var using registers, avoiding the need to write and
read stack.

The improvement is significant on powerpc:
Before:
gettimeofday:    vdso: 1379 nsec/call
clock-gettime-realtime-coarse:    vdso: 868 nsec/call
clock-gettime-realtime:    vdso: 1511 nsec/call
clock-gettime-monotonic-raw:    vdso: 1576 nsec/call

After:
gettimeofday:    vdso: 1078 nsec/call
clock-gettime-realtime-coarse:    vdso: 807 nsec/call
clock-gettime-realtime:    vdso: 1256 nsec/call
clock-gettime-monotonic-raw:    vdso: 1316 nsec/call

At the same time, change the return type of do_coarse() to int, this
increase readability of the if/elseif/elseif/else  section
in __cvdso_clock_gettime_common()

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 lib/vdso/gettimeofday.c | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index 42bd8ab955fa..d75e44ba716f 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -38,8 +38,8 @@ u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
 }
 #endif
 
-static int do_hres(const struct vdso_data *vd, clockid_t clk,
-		   struct __kernel_timespec *ts)
+static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
+				   struct __kernel_timespec *ts)
 {
 	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
 	u64 cycles, last, sec, ns;
@@ -68,8 +68,8 @@ static int do_hres(const struct vdso_data *vd, clockid_t clk,
 	return 0;
 }
 
-static void do_coarse(const struct vdso_data *vd, clockid_t clk,
-		      struct __kernel_timespec *ts)
+static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk,
+				     struct __kernel_timespec *ts)
 {
 	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
 	u32 seq;
@@ -79,6 +79,8 @@ static void do_coarse(const struct vdso_data *vd, clockid_t clk,
 		ts->tv_sec = vdso_ts->sec;
 		ts->tv_nsec = vdso_ts->nsec;
 	} while (unlikely(vdso_read_retry(vd, seq)));
+
+	return 0;
 }
 
 static __maybe_unused int
@@ -96,15 +98,16 @@ __cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
 	 * clocks are handled in the VDSO directly.
 	 */
 	msk = 1U << clock;
-	if (likely(msk & VDSO_HRES)) {
-		return do_hres(&vd[CS_HRES_COARSE], clock, ts);
-	} else if (msk & VDSO_COARSE) {
-		do_coarse(&vd[CS_HRES_COARSE], clock, ts);
-		return 0;
-	} else if (msk & VDSO_RAW) {
-		return do_hres(&vd[CS_RAW], clock, ts);
-	}
-	return -1;
+	if (likely(msk & VDSO_HRES))
+		vd += CS_HRES_COARSE;
+	else if (msk & VDSO_COARSE)
+		return do_coarse(&vd[CS_HRES_COARSE], clock, ts);
+	else if (msk & VDSO_RAW)
+		vd += CS_RAW;
+	else
+		return -1;
+
+	return do_hres(vd, clock, ts);
 }
 
 static __maybe_unused int
-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 05/12] lib: vdso: Avoid duplication in __cvdso_clock_getres()
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
                   ` (3 preceding siblings ...)
  2020-01-13 17:08 ` [RFC PATCH v3 04/12] lib: vdso: inline do_hres() and do_coarse() Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 06/12] lib: vdso: __iter_div_u64_rem() is suboptimal for 32 bit time Christophe Leroy
                   ` (6 subsequent siblings)
  11 siblings, 0 replies; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

VDSO_HRES and VDSO_RAW clocks are handled the same way.

Don't duplicate code.

Before the patch:
clock-getres-monotonic-raw:    vdso: 737 nsec/call
clock-getres-monotonic-coarse:    vdso: 753 nsec/call
clock-getres-monotonic:    vdso: 691 nsec/call

After the patch:
clock-getres-monotonic-raw:    vdso: 715 nsec/call
clock-getres-monotonic-coarse:    vdso: 715 nsec/call
clock-getres-monotonic:    vdso: 714 nsec/call

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Reviewed-by: Andy Lutomirski <luto@kernel.org>
---
 lib/vdso/gettimeofday.c | 11 ++---------
 1 file changed, 2 insertions(+), 9 deletions(-)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index d75e44ba716f..decd3f2b37af 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -184,7 +184,6 @@ static __maybe_unused
 int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
 {
 	const struct vdso_data *vd = __arch_get_vdso_data();
-	u64 hrtimer_res;
 	u32 msk;
 	u64 ns;
 
@@ -192,27 +191,21 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
 	if (unlikely((u32) clock >= MAX_CLOCKS))
 		return -1;
 
-	hrtimer_res = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
 	/*
 	 * Convert the clockid to a bitmask and use it to check which
 	 * clocks are handled in the VDSO directly.
 	 */
 	msk = 1U << clock;
-	if (msk & VDSO_HRES) {
+	if (msk & (VDSO_HRES | VDSO_RAW)) {
 		/*
 		 * Preserves the behaviour of posix_get_hrtimer_res().
 		 */
-		ns = hrtimer_res;
+		ns = READ_ONCE(vd[CS_HRES_COARSE].hrtimer_res);
 	} else if (msk & VDSO_COARSE) {
 		/*
 		 * Preserves the behaviour of posix_get_coarse_res().
 		 */
 		ns = LOW_RES_NSEC;
-	} else if (msk & VDSO_RAW) {
-		/*
-		 * Preserves the behaviour of posix_get_hrtimer_res().
-		 */
-		ns = hrtimer_res;
 	} else {
 		return -1;
 	}
-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 06/12] lib: vdso: __iter_div_u64_rem() is suboptimal for 32 bit time
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
                   ` (4 preceding siblings ...)
  2020-01-13 17:08 ` [RFC PATCH v3 05/12] lib: vdso: Avoid duplication in __cvdso_clock_getres() Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  2020-01-14 11:31   ` Thomas Gleixner
  2020-01-13 17:08 ` [RFC PATCH v3 07/12] powerpc/vdso: simplify __get_datapage() Christophe Leroy
                   ` (5 subsequent siblings)
  11 siblings, 1 reply; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

Using __iter_div_ulong_rem() is suboptimal on 32 bits.
Nanoseconds are only 32 bits, and VDSO data is updated every 10ms
so nsec will never overflow 32 bits.

Add an equivalent of __iter_div_u64_rem() but based
on unsigned long to better fit with 32 bits arches.

Before:
gettimeofday:    vdso: 1078 nsec/call
clock-gettime-monotonic-raw:    vdso: 1317 nsec/call
clock-gettime-monotonic:    vdso: 1255 nsec/call

After:
gettimeofday:    vdso: 1032 nsec/call
clock-gettime-monotonic-raw:    vdso: 1312 nsec/call
clock-gettime-monotonic:    vdso: 1243 nsec/call
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 lib/vdso/gettimeofday.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index decd3f2b37af..da15a8842825 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -38,12 +38,32 @@ u64 vdso_calc_delta(u64 cycles, u64 last, u64 mask, u32 mult)
 }
 #endif
 
+static __always_inline u32
+__iter_div_ulong_rem(unsigned long dividend, u32 divisor, unsigned long *remainder)
+{
+	u32 ret = 0;
+
+	while (dividend >= divisor) {
+		/* The following asm() prevents the compiler from
+		   optimising this loop into a modulo operation.  */
+		asm("" : "+rm"(dividend));
+
+		dividend -= divisor;
+		ret++;
+	}
+
+	*remainder = dividend;
+
+	return ret;
+}
+
 static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
 				   struct __kernel_timespec *ts)
 {
 	const struct vdso_timestamp *vdso_ts = &vd->basetime[clk];
 	u64 cycles, last, sec, ns;
 	u32 seq;
+	unsigned long nsec;
 
 	do {
 		seq = vdso_read_begin(vd);
@@ -54,7 +74,7 @@ static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
 			return -1;
 
 		ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
-		ns >>= vd->shift;
+		nsec = ns >> vd->shift;
 		sec = vdso_ts->sec;
 	} while (unlikely(vdso_read_retry(vd, seq)));
 
@@ -62,8 +82,8 @@ static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
 	 * Do this outside the loop: a race inside the loop could result
 	 * in __iter_div_u64_rem() being extremely slow.
 	 */
-	ts->tv_sec = sec + __iter_div_u64_rem(ns, NSEC_PER_SEC, &ns);
-	ts->tv_nsec = ns;
+	ts->tv_sec = sec + __iter_div_ulong_rem(nsec, NSEC_PER_SEC, &nsec);
+	ts->tv_nsec = nsec;
 
 	return 0;
 }
-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 07/12] powerpc/vdso: simplify __get_datapage()
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
                   ` (5 preceding siblings ...)
  2020-01-13 17:08 ` [RFC PATCH v3 06/12] lib: vdso: __iter_div_u64_rem() is suboptimal for 32 bit time Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer Christophe Leroy
                   ` (4 subsequent siblings)
  11 siblings, 0 replies; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

The VDSO datapage and the text pages are always located immediately
next to each other, so it can be hardcoded without an indirection
through __kernel_datapage_offset

In order to ease things, move the data page in front like other
arches, that way there is no need to know the size of the library
to locate the data page.

Before:
clock-getres-realtime-coarse:    vdso: 714 nsec/call
clock-gettime-realtime-coarse:    vdso: 792 nsec/call
clock-gettime-realtime:    vdso: 1243 nsec/call

After:
clock-getres-realtime-coarse:    vdso: 699 nsec/call
clock-gettime-realtime-coarse:    vdso: 784 nsec/call
clock-gettime-realtime:    vdso: 1231 nsec/call
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/kernel/vdso.c              | 53 +++++----------------------------
 arch/powerpc/kernel/vdso32/datapage.S   | 10 +++----
 arch/powerpc/kernel/vdso32/vdso32.lds.S |  7 ++---
 arch/powerpc/kernel/vdso64/datapage.S   | 10 +++----
 arch/powerpc/kernel/vdso64/vdso64.lds.S |  7 ++---
 5 files changed, 19 insertions(+), 68 deletions(-)

diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index 16a44bffe698..c093d90a222a 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -191,7 +191,7 @@ int arch_setup_additional_pages(struct linux_binprm *bprm, int uses_interp)
 	 * install_special_mapping or the perf counter mmap tracking code
 	 * will fail to recognise it as a vDSO (since arch_vma_name fails).
 	 */
-	current->mm->context.vdso_base = vdso_base;
+	current->mm->context.vdso_base = vdso_base + PAGE_SIZE;
 
 	/*
 	 * our vma flags don't have VM_WRITE so by default, the process isn't
@@ -488,42 +488,6 @@ static __init void vdso_setup_trampolines(struct lib32_elfinfo *v32,
 	vdso32_rt_sigtramp = find_function32(v32, "__kernel_sigtramp_rt32");
 }
 
-static __init int vdso_fixup_datapage(struct lib32_elfinfo *v32,
-				       struct lib64_elfinfo *v64)
-{
-#ifdef CONFIG_VDSO32
-	Elf32_Sym *sym32;
-#endif
-#ifdef CONFIG_PPC64
-	Elf64_Sym *sym64;
-
-       	sym64 = find_symbol64(v64, "__kernel_datapage_offset");
-	if (sym64 == NULL) {
-		printk(KERN_ERR "vDSO64: Can't find symbol "
-		       "__kernel_datapage_offset !\n");
-		return -1;
-	}
-	*((int *)(vdso64_kbase + sym64->st_value - VDSO64_LBASE)) =
-		(vdso64_pages << PAGE_SHIFT) -
-		(sym64->st_value - VDSO64_LBASE);
-#endif /* CONFIG_PPC64 */
-
-#ifdef CONFIG_VDSO32
-	sym32 = find_symbol32(v32, "__kernel_datapage_offset");
-	if (sym32 == NULL) {
-		printk(KERN_ERR "vDSO32: Can't find symbol "
-		       "__kernel_datapage_offset !\n");
-		return -1;
-	}
-	*((int *)(vdso32_kbase + (sym32->st_value - VDSO32_LBASE))) =
-		(vdso32_pages << PAGE_SHIFT) -
-		(sym32->st_value - VDSO32_LBASE);
-#endif
-
-	return 0;
-}
-
-
 static __init int vdso_fixup_features(struct lib32_elfinfo *v32,
 				      struct lib64_elfinfo *v64)
 {
@@ -624,9 +588,6 @@ static __init int vdso_setup(void)
 	if (vdso_do_find_sections(&v32, &v64))
 		return -1;
 
-	if (vdso_fixup_datapage(&v32, &v64))
-		return -1;
-
 	if (vdso_fixup_features(&v32, &v64))
 		return -1;
 
@@ -771,26 +732,26 @@ static int __init vdso_init(void)
 	vdso32_pagelist = kcalloc(vdso32_pages + 2, sizeof(struct page *),
 				  GFP_KERNEL);
 	BUG_ON(vdso32_pagelist == NULL);
+	vdso32_pagelist[0] = virt_to_page(vdso_data);
 	for (i = 0; i < vdso32_pages; i++) {
 		struct page *pg = virt_to_page(vdso32_kbase + i*PAGE_SIZE);
 		get_page(pg);
-		vdso32_pagelist[i] = pg;
+		vdso32_pagelist[i + 1] = pg;
 	}
-	vdso32_pagelist[i++] = virt_to_page(vdso_data);
-	vdso32_pagelist[i] = NULL;
+	vdso32_pagelist[i + 1] = NULL;
 #endif
 
 #ifdef CONFIG_PPC64
 	vdso64_pagelist = kcalloc(vdso64_pages + 2, sizeof(struct page *),
 				  GFP_KERNEL);
 	BUG_ON(vdso64_pagelist == NULL);
+	vdso64_pagelist[0] = virt_to_page(vdso_data);
 	for (i = 0; i < vdso64_pages; i++) {
 		struct page *pg = virt_to_page(vdso64_kbase + i*PAGE_SIZE);
 		get_page(pg);
-		vdso64_pagelist[i] = pg;
+		vdso64_pagelist[i + 1] = pg;
 	}
-	vdso64_pagelist[i++] = virt_to_page(vdso_data);
-	vdso64_pagelist[i] = NULL;
+	vdso64_pagelist[i + 1] = NULL;
 #endif /* CONFIG_PPC64 */
 
 	get_page(virt_to_page(vdso_data));
diff --git a/arch/powerpc/kernel/vdso32/datapage.S b/arch/powerpc/kernel/vdso32/datapage.S
index 6c7401bd284e..d839aa1a4f01 100644
--- a/arch/powerpc/kernel/vdso32/datapage.S
+++ b/arch/powerpc/kernel/vdso32/datapage.S
@@ -12,9 +12,6 @@
 #include <asm/vdso.h>
 
 	.text
-	.global	__kernel_datapage_offset;
-__kernel_datapage_offset:
-	.long	0
 
 V_FUNCTION_BEGIN(__get_datapage)
   .cfi_startproc
@@ -31,10 +28,11 @@ V_FUNCTION_BEGIN(__get_datapage)
 data_page_branch:
 	mflr	r3
 	mtlr	r0
-	addi	r3, r3, __kernel_datapage_offset-data_page_branch
-	lwz	r0,0(r3)
+#if CONFIG_PPC_PAGE_SHIFT > 14
+	addis	r3, r3, (_vdso_datapage - data_page_branch)@ha
+#endif
+	addi	r3, r3, (_vdso_datapage - data_page_branch)@l
   .cfi_restore lr
-	add	r3,r0,r3
 	blr
   .cfi_endproc
 V_FUNCTION_END(__get_datapage)
diff --git a/arch/powerpc/kernel/vdso32/vdso32.lds.S b/arch/powerpc/kernel/vdso32/vdso32.lds.S
index 9400b182e163..f09c2354bd21 100644
--- a/arch/powerpc/kernel/vdso32/vdso32.lds.S
+++ b/arch/powerpc/kernel/vdso32/vdso32.lds.S
@@ -4,6 +4,7 @@
  * library
  */
 #include <asm/vdso.h>
+#include <asm/page.h>
 
 #ifdef __LITTLE_ENDIAN__
 OUTPUT_FORMAT("elf32-powerpcle", "elf32-powerpcle", "elf32-powerpcle")
@@ -15,6 +16,7 @@ ENTRY(_start)
 
 SECTIONS
 {
+	PROVIDE(_vdso_datapage = . - PAGE_SIZE);
 	. = VDSO32_LBASE + SIZEOF_HEADERS;
 
 	.hash          	: { *(.hash) }			:text
@@ -138,11 +140,6 @@ VERSION
 {
 	VDSO_VERSION_STRING {
 	global:
-		/*
-		 * Has to be there for the kernel to find
-		 */
-		__kernel_datapage_offset;
-
 		__kernel_get_syscall_map;
 #if defined(CONFIG_PPC32) && !defined(CONFIG_PPC_BOOK3S_601)
 		__kernel_gettimeofday;
diff --git a/arch/powerpc/kernel/vdso64/datapage.S b/arch/powerpc/kernel/vdso64/datapage.S
index 4808ce9eeb3d..8c41e1a93980 100644
--- a/arch/powerpc/kernel/vdso64/datapage.S
+++ b/arch/powerpc/kernel/vdso64/datapage.S
@@ -12,9 +12,6 @@
 #include <asm/vdso.h>
 
 	.text
-.global	__kernel_datapage_offset;
-__kernel_datapage_offset:
-	.long	0
 
 _GLOBAL(__get_datapage)
   .cfi_startproc
@@ -31,10 +28,11 @@ _GLOBAL(__get_datapage)
 data_page_branch:
 	mflr	r3
 	mtlr	r0
-	addi	r3, r3, __kernel_datapage_offset-data_page_branch
-	lwz	r0,0(r3)
+#if CONFIG_PPC_PAGE_SHIFT > 14
+	addis	r3, r3, (_vdso_datapage - data_page_branch)@ha
+#endif
+	addi	r3, r3, (_vdso_datapage - data_page_branch)@l
   .cfi_restore lr
-	add	r3,r0,r3
 	blr
   .cfi_endproc
 
diff --git a/arch/powerpc/kernel/vdso64/vdso64.lds.S b/arch/powerpc/kernel/vdso64/vdso64.lds.S
index 256fb9720298..f58c7e2e9cbd 100644
--- a/arch/powerpc/kernel/vdso64/vdso64.lds.S
+++ b/arch/powerpc/kernel/vdso64/vdso64.lds.S
@@ -4,6 +4,7 @@
  * library
  */
 #include <asm/vdso.h>
+#include <asm/page.h>
 
 #ifdef __LITTLE_ENDIAN__
 OUTPUT_FORMAT("elf64-powerpcle", "elf64-powerpcle", "elf64-powerpcle")
@@ -15,6 +16,7 @@ ENTRY(_start)
 
 SECTIONS
 {
+	PROVIDE(_vdso_datapage = . - PAGE_SIZE);
 	. = VDSO64_LBASE + SIZEOF_HEADERS;
 
 	.hash		: { *(.hash) }			:text
@@ -138,11 +140,6 @@ VERSION
 {
 	VDSO_VERSION_STRING {
 	global:
-		/*
-		 * Has to be there for the kernel to find
-		 */
-		__kernel_datapage_offset;
-
 		__kernel_get_syscall_map;
 		__kernel_gettimeofday;
 		__kernel_clock_gettime;
-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
                   ` (6 preceding siblings ...)
  2020-01-13 17:08 ` [RFC PATCH v3 07/12] powerpc/vdso: simplify __get_datapage() Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  2020-01-14 23:06   ` Thomas Gleixner
  2020-01-13 17:08 ` [RFC PATCH v3 09/12] powerpc/vdso: provide inline alternative to __get_datapage() Christophe Leroy
                   ` (3 subsequent siblings)
  11 siblings, 1 reply; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

On powerpc, __arch_get_vdso_data() clobbers the link register,
requiring the caller to save it.

As the parent function already has to set a stack frame and saves
the link register before calling the C vdso function, retriving the
vdso data pointer there is lighter.

Give arches the opportunity to hand the vdso data pointer
to C vdso functions.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 lib/vdso/gettimeofday.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index da15a8842825..ea1a55507af5 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -104,9 +104,15 @@ static __always_inline int do_coarse(const struct vdso_data *vd, clockid_t clk,
 }
 
 static __maybe_unused int
+#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
+__cvdso_clock_gettime_common(const struct vdso_data *vd, clockid_t clock,
+		      struct __kernel_timespec *ts)
+{
+#else
 __cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
 {
 	const struct vdso_data *vd = __arch_get_vdso_data();
+#endif
 	u32 msk;
 
 	/* Check for negative values or invalid clocks */
@@ -131,9 +137,16 @@ __cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
 }
 
 static __maybe_unused int
+#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
+__cvdso_clock_gettime(const struct vdso_data *vd, clockid_t clock,
+		      struct __kernel_timespec *ts)
+{
+	int ret = __cvdso_clock_gettime_common(vd, clock, ts);
+#else
 __cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
 {
 	int ret = __cvdso_clock_gettime_common(clock, ts);
+#endif
 
 	if (unlikely(ret))
 		return clock_gettime_fallback(clock, ts);
@@ -141,12 +154,21 @@ __cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
 }
 
 static __maybe_unused int
+#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
+__cvdso_clock_gettime32(const struct vdso_data *vd, clockid_t clock,
+			struct old_timespec32 *res)
+#else
 __cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
+#endif
 {
 	struct __kernel_timespec ts;
 	int ret;
 
+#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
+	ret = __cvdso_clock_gettime_common(vd, clock, &ts);
+#else
 	ret = __cvdso_clock_gettime_common(clock, &ts);
+#endif
 
 #ifdef VDSO_HAS_32BIT_FALLBACK
 	if (unlikely(ret))
@@ -164,9 +186,15 @@ __cvdso_clock_gettime32(clockid_t clock, struct old_timespec32 *res)
 }
 
 static __maybe_unused int
+#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
+__cvdso_gettimeofday(const struct vdso_data *vd, struct __kernel_old_timeval *tv,
+		     struct timezone *tz)
+{
+#else
 __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 {
 	const struct vdso_data *vd = __arch_get_vdso_data();
+#endif
 
 	if (likely(tv != NULL)) {
 		struct __kernel_timespec ts;
@@ -187,9 +215,15 @@ __cvdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
 }
 
 #ifdef VDSO_HAS_TIME
+#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
+static __maybe_unused __kernel_old_time_t
+__cvdso_time(const struct vdso_data *vd, __kernel_old_time_t *time)
+{
+#else
 static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time)
 {
 	const struct vdso_data *vd = __arch_get_vdso_data();
+#endif
 	__kernel_old_time_t t = READ_ONCE(vd[CS_HRES_COARSE].basetime[CLOCK_REALTIME].sec);
 
 	if (time)
@@ -201,9 +235,15 @@ static __maybe_unused __kernel_old_time_t __cvdso_time(__kernel_old_time_t *time
 
 #ifdef VDSO_HAS_CLOCK_GETRES
 static __maybe_unused
+#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
+int __cvdso_clock_getres_common(const struct vdso_data *vd, clockid_t clock,
+				struct __kernel_timespec *res)
+{
+#else
 int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
 {
 	const struct vdso_data *vd = __arch_get_vdso_data();
+#endif
 	u32 msk;
 	u64 ns;
 
@@ -238,9 +278,16 @@ int __cvdso_clock_getres_common(clockid_t clock, struct __kernel_timespec *res)
 }
 
 static __maybe_unused
+#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
+int __cvdso_clock_getres(const struct vdso_data *vd, clockid_t clock,
+			 struct __kernel_timespec *res)
+{
+	int ret = __cvdso_clock_getres_common(vd, clock, res);
+#else
 int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
 {
 	int ret = __cvdso_clock_getres_common(clock, res);
+#endif
 
 	if (unlikely(ret))
 		return clock_getres_fallback(clock, res);
@@ -248,12 +295,21 @@ int __cvdso_clock_getres(clockid_t clock, struct __kernel_timespec *res)
 }
 
 static __maybe_unused int
+#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
+__cvdso_clock_getres_time32(const struct vdso_data *vd, clockid_t clock,
+			    struct old_timespec32 *res)
+#else
 __cvdso_clock_getres_time32(clockid_t clock, struct old_timespec32 *res)
+#endif
 {
 	struct __kernel_timespec ts;
 	int ret;
 
+#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
+	ret = __cvdso_clock_getres_common(vd, clock, &ts);
+#else
 	ret = __cvdso_clock_getres_common(clock, &ts);
+#endif
 
 #ifdef VDSO_HAS_32BIT_FALLBACK
 	if (unlikely(ret))
-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 09/12] powerpc/vdso: provide inline alternative to __get_datapage()
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
                   ` (7 preceding siblings ...)
  2020-01-13 17:08 ` [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 10/12] powerpc/vdso: provide vdso data pointer from the ASM caller Christophe Leroy
                   ` (2 subsequent siblings)
  11 siblings, 0 replies; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

__get_datapage() is only a few instructions to retrieve the
address of the page where the kernel stores data to the VDSO.

By inlining this function into its users, a bl/blr pair and
a mflr/mtlr pair is avoided, plus a few reg moves.

The improvement is noticeable (about 55 nsec/call on an 8xx)

With current __get_datapage() function:
gettimeofday:    vdso: 731 nsec/call
clock-gettime-realtime-coarse:    vdso: 668 nsec/call
clock-gettime-monotonic-coarse:    vdso: 745 nsec/call

Using the __get_datapage macro provided by this patch:
gettimeofday:    vdso: 677 nsec/call
clock-gettime-realtime-coarse:    vdso: 613 nsec/call
clock-gettime-monotonic-coarse:    vdso: 690 nsec/call

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/vdso_datapage.h | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/arch/powerpc/include/asm/vdso_datapage.h b/arch/powerpc/include/asm/vdso_datapage.h
index 4d7965bf369e..7342cc0c1ae4 100644
--- a/arch/powerpc/include/asm/vdso_datapage.h
+++ b/arch/powerpc/include/asm/vdso_datapage.h
@@ -105,6 +105,17 @@ struct vdso_arch_data {
 
 extern struct vdso_arch_data *vdso_data;
 
+#else /* __ASSEMBLY__ */
+
+.macro get_datapage ptr, offset=0
+	bcl	20, 31, .+4
+	mflr	\ptr
+#if CONFIG_PPC_PAGE_SHIFT > 14
+	addis	\ptr, \ptr, (_vdso_datapage + \offset - (.-4))@ha
+#endif
+	addi	\ptr, \ptr, (_vdso_datapage + \offset - (.-4))@l
+.endm
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* __KERNEL__ */
-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 10/12] powerpc/vdso: provide vdso data pointer from the ASM caller.
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
                   ` (8 preceding siblings ...)
  2020-01-13 17:08 ` [RFC PATCH v3 09/12] powerpc/vdso: provide inline alternative to __get_datapage() Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 11/12] lib: vdso: split clock verification out of __arch_get_hw_counter() Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 12/12] powerpc/vdso: provide __arch_is_hw_counter_valid() Christophe Leroy
  11 siblings, 0 replies; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

__arch_get_vdso_data() clobbers the link register, requiring
the caller to save it.

As the ASM calling function already has to set a stack frame and
saves the link register before calling the C vdso function,
retriving the vdso data pointer there is lighter.

The improvement is significant:

Before:
gettimeofday:    vdso: 1027 nsec/call
clock-getres-realtime-coarse:    vdso: 699 nsec/call
clock-gettime-realtime-coarse:    vdso: 784 nsec/call
clock-gettime-realtime:    vdso: 1231 nsec/call

After:
gettimeofday:    vdso: 908 nsec/call
clock-getres-realtime-coarse:    vdso: 545 nsec/call
clock-gettime-realtime-coarse:    vdso: 617 nsec/call
clock-gettime-realtime:    vdso: 1078 nsec/call

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/vdso/gettimeofday.h | 12 ++----------
 arch/powerpc/kernel/vdso32/gettimeofday.S    |  3 +++
 arch/powerpc/kernel/vdso32/vgettimeofday.c   | 19 +++++++++++--------
 arch/powerpc/kernel/vdso64/gettimeofday.S    |  3 +++
 arch/powerpc/kernel/vdso64/vgettimeofday.c   | 19 +++++++++++--------
 5 files changed, 30 insertions(+), 26 deletions(-)

diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
index 343c81a7e951..d1e702e0ea86 100644
--- a/arch/powerpc/include/asm/vdso/gettimeofday.h
+++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
@@ -6,13 +6,14 @@
 
 #include <asm/time.h>
 #include <asm/unistd.h>
-#include <asm/vdso_datapage.h>
 #include <uapi/linux/time.h>
 
 #define VDSO_HAS_CLOCK_GETRES		1
 
 #define VDSO_HAS_TIME			1
 
+#define VDSO_GETS_VD_PTR_FROM_ARCH	1
+
 static __always_inline int do_syscall_2(const unsigned long _r0, const unsigned long _r3,
 					const unsigned long _r4)
 {
@@ -80,15 +81,6 @@ static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
 	return get_tb();
 }
 
-void *__get_datapage(void);
-
-static __always_inline const struct vdso_data *__arch_get_vdso_data(void)
-{
-	struct vdso_arch_data *vdso_data = __get_datapage();
-
-	return vdso_data->data;
-}
-
 /*
  * powerpc specific delta calculation.
  *
diff --git a/arch/powerpc/kernel/vdso32/gettimeofday.S b/arch/powerpc/kernel/vdso32/gettimeofday.S
index ba0bd64b3da3..0d43878e462c 100644
--- a/arch/powerpc/kernel/vdso32/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso32/gettimeofday.S
@@ -9,6 +9,7 @@
 #include <asm/processor.h>
 #include <asm/ppc_asm.h>
 #include <asm/vdso.h>
+#include <asm/vdso_datapage.h>
 #include <asm/asm-offsets.h>
 #include <asm/unistd.h>
 
@@ -18,6 +19,7 @@
 	stwu	r1, -16(r1)
 	mflr	r0
 	stw	r0, 20(r1)
+	get_datapage	r5, VDSO_DATA_OFFSET
 	bl	\funct
 	lwz	r0, 20(r1)
 	cmpwi	r3, 0
@@ -79,6 +81,7 @@ V_FUNCTION_BEGIN(__kernel_time)
 	stwu	r1, -16(r1)
 	mflr	r0
 	stw	r0, 20(r1)
+	get_datapage	r4, VDSO_DATA_OFFSET
 	bl	__c_kernel_time
 	lwz	r0, 20(r1)
 	crclr	cr0*4+so
diff --git a/arch/powerpc/kernel/vdso32/vgettimeofday.c b/arch/powerpc/kernel/vdso32/vgettimeofday.c
index 4ed1bf2ae30e..7fdccf896a9c 100644
--- a/arch/powerpc/kernel/vdso32/vgettimeofday.c
+++ b/arch/powerpc/kernel/vdso32/vgettimeofday.c
@@ -5,22 +5,25 @@
 #include <linux/time.h>
 #include <linux/types.h>
 
-int __c_kernel_clock_gettime(clockid_t clock, struct old_timespec32 *ts)
+int __c_kernel_clock_gettime(clockid_t clock, struct old_timespec32 *ts,
+			     const struct vdso_data *vd)
 {
-	return __cvdso_clock_gettime32(clock, ts);
+	return __cvdso_clock_gettime32(vd, clock, ts);
 }
 
-int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
+int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
+			    const struct vdso_data *vd)
 {
-	return __cvdso_gettimeofday(tv, tz);
+	return __cvdso_gettimeofday(vd, tv, tz);
 }
 
-int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res)
+int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res,
+			    const struct vdso_data *vd)
 {
-	return __cvdso_clock_getres_time32(clock_id, res);
+	return __cvdso_clock_getres_time32(vd, clock_id, res);
 }
 
-time_t __c_kernel_time(time_t *time)
+time_t __c_kernel_time(time_t *time, const struct vdso_data *vd)
 {
-	return __cvdso_time(time);
+	return __cvdso_time(vd, time);
 }
diff --git a/arch/powerpc/kernel/vdso64/gettimeofday.S b/arch/powerpc/kernel/vdso64/gettimeofday.S
index 22f4f1f73bbc..f61c53eb6600 100644
--- a/arch/powerpc/kernel/vdso64/gettimeofday.S
+++ b/arch/powerpc/kernel/vdso64/gettimeofday.S
@@ -9,6 +9,7 @@
 #include <asm/processor.h>
 #include <asm/ppc_asm.h>
 #include <asm/vdso.h>
+#include <asm/vdso_datapage.h>
 #include <asm/asm-offsets.h>
 #include <asm/unistd.h>
 
@@ -18,6 +19,7 @@
 	mflr	r0
 	std	r0, 16(r1)
 	stdu	r1, -128(r1)
+	get_datapage	r5, VDSO_DATA_OFFSET
 	bl	\funct
 	addi	r1, r1, 128
 	ld	r0, 16(r1)
@@ -79,6 +81,7 @@ V_FUNCTION_BEGIN(__kernel_time)
 	mflr	r0
 	std	r0, 16(r1)
 	stdu	r1, -128(r1)
+	get_datapage	r4, VDSO_DATA_OFFSET
 	bl	__c_kernel_time
 	addi	r1, r1, 128
 	ld	r0, 16(r1)
diff --git a/arch/powerpc/kernel/vdso64/vgettimeofday.c b/arch/powerpc/kernel/vdso64/vgettimeofday.c
index 407c6a7ed4e2..4917d7a92a0c 100644
--- a/arch/powerpc/kernel/vdso64/vgettimeofday.c
+++ b/arch/powerpc/kernel/vdso64/vgettimeofday.c
@@ -5,22 +5,25 @@
 #include <linux/time.h>
 #include <linux/types.h>
 
-int __c_kernel_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
+int __c_kernel_clock_gettime(clockid_t clock, struct __kernel_timespec *ts,
+			     const struct vdso_data *vd)
 {
-	return __cvdso_clock_gettime(clock, ts);
+	return __cvdso_clock_gettime(vd, clock, ts);
 }
 
-int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz)
+int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz,
+			    const struct vdso_data *vd)
 {
-	return __cvdso_gettimeofday(tv, tz);
+	return __cvdso_gettimeofday(vd, tv, tz);
 }
 
-int __c_kernel_clock_getres(clockid_t clock_id, struct __kernel_timespec *res)
+int __c_kernel_clock_getres(clockid_t clock_id, struct __kernel_timespec *res,
+			    const struct vdso_data *vd)
 {
-	return __cvdso_clock_getres(clock_id, res);
+	return __cvdso_clock_getres(vd, clock_id, res);
 }
 
-time_t __c_kernel_time(time_t *time)
+time_t __c_kernel_time(time_t *time, const struct vdso_data *vd)
 {
-	return __cvdso_time(time);
+	return __cvdso_time(vd, time);
 }
-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 11/12] lib: vdso: split clock verification out of __arch_get_hw_counter()
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
                   ` (9 preceding siblings ...)
  2020-01-13 17:08 ` [RFC PATCH v3 10/12] powerpc/vdso: provide vdso data pointer from the ASM caller Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  2020-01-13 17:08 ` [RFC PATCH v3 12/12] powerpc/vdso: provide __arch_is_hw_counter_valid() Christophe Leroy
  11 siblings, 0 replies; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

__arch_get_hw_counter() returns the current value of the counter if
the counter is valid or a negative number if the counter is not valid.

This is suboptimal because the validity is checked twice: once before
reading the counter and once after reading the counter.

Optionaly split the verification out of __arch_get_hw_counter()
by providing an optional __arch_is_hw_counter_valid() function.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 lib/vdso/gettimeofday.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/vdso/gettimeofday.c b/lib/vdso/gettimeofday.c
index ea1a55507af5..001f6329e846 100644
--- a/lib/vdso/gettimeofday.c
+++ b/lib/vdso/gettimeofday.c
@@ -67,11 +67,18 @@ static __always_inline int do_hres(const struct vdso_data *vd, clockid_t clk,
 
 	do {
 		seq = vdso_read_begin(vd);
+#ifdef __arch_is_hw_counter_valid
+		if (unlikely(!__arch_is_hw_counter_valid(vd->clock_mode)))
+			return -1;
+#endif
+
 		cycles = __arch_get_hw_counter(vd->clock_mode);
 		ns = vdso_ts->nsec;
 		last = vd->cycle_last;
+#ifndef __arch_is_hw_counter_valid
 		if (unlikely((s64)cycles < 0))
 			return -1;
+#endif
 
 		ns += vdso_calc_delta(cycles, last, vd->mask, vd->mult);
 		nsec = ns >> vd->shift;
-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* [RFC PATCH v3 12/12] powerpc/vdso: provide __arch_is_hw_counter_valid()
  2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
                   ` (10 preceding siblings ...)
  2020-01-13 17:08 ` [RFC PATCH v3 11/12] lib: vdso: split clock verification out of __arch_get_hw_counter() Christophe Leroy
@ 2020-01-13 17:08 ` Christophe Leroy
  11 siblings, 0 replies; 19+ messages in thread
From: Christophe Leroy @ 2020-01-13 17:08 UTC (permalink / raw)
  To: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	tglx, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

To avoid a double verification of the hw_counter validity,
provide __arch_is_hw_counter_valid()

Before:
clock-gettime-realtime:    vdso: 1078 nsec/call

After:
clock-gettime-realtime:    vdso: 1064 nsec/call

The * shows the test of the clock type.
The > shows the additional test on the counter,
that goes away with this patch

Before:
 5e0:	81 25 00 04 	lwz     r9,4(r5)
*5e4:	2f 89 00 00 	cmpwi   cr7,r9,0
*5e8:	40 9e 01 3c 	bne     cr7,724 <__c_kernel_clock_gettime+0x17c>
 5ec:	94 21 ff e0 	stwu    r1,-32(r1)
 5f0:	93 61 00 0c 	stw     r27,12(r1)
 5f4:	93 81 00 10 	stw     r28,16(r1)
 5f8:	93 a1 00 14 	stw     r29,20(r1)
 5fc:	93 c1 00 18 	stw     r30,24(r1)
 600:	93 e1 00 1c 	stw     r31,28(r1)
 604:	7d 8d 42 e6 	mftbu   r12
 608:	7f ac 42 e6 	mftb    r29
 60c:	7c cd 42 e6 	mftbu   r6
 610:	7f 8c 30 40 	cmplw   cr7,r12,r6
 614:	40 9e ff f0 	bne     cr7,604 <__c_kernel_clock_gettime+0x5c>
>618:	2f 8c 00 00 	cmpwi   cr7,r12,0
 61c:	83 6b 00 28 	lwz     r27,40(r11)
 620:	83 8b 00 2c 	lwz     r28,44(r11)
 624:	81 45 00 08 	lwz     r10,8(r5)
 628:	80 e5 00 0c 	lwz     r7,12(r5)
>62c:	41 9c 00 b4 	blt     cr7,6e0 <__c_kernel_clock_gettime+0x138>
 630:	81 05 00 18 	lwz     r8,24(r5)
 634:	83 c5 00 1c 	lwz     r30,28(r5)
 638:	80 cb 00 24 	lwz     r6,36(r11)
 63c:	83 e5 00 00 	lwz     r31,0(r5)
 640:	7f 9f 00 40 	cmplw   cr7,r31,r0
 644:	40 9e 00 84 	bne     cr7,6c8 <__c_kernel_clock_gettime+0x120>

After:
 5e0:	81 25 00 04 	lwz     r9,4(r5)
*5e4:	2f 89 00 00 	cmpwi   cr7,r9,0
*5e8:	40 9e 01 88 	bne     cr7,770 <__c_kernel_clock_gettime+0x1c8>
 5ec:	94 21 ff e0 	stwu    r1,-32(r1)
 5f0:	93 61 00 0c 	stw     r27,12(r1)
 5f4:	93 81 00 10 	stw     r28,16(r1)
 5f8:	93 a1 00 14 	stw     r29,20(r1)
 5fc:	93 c1 00 18 	stw     r30,24(r1)
 600:	93 e1 00 1c 	stw     r31,28(r1)
 604:	7f cd 42 e6 	mftbu   r30
 608:	7f ac 42 e6 	mftb    r29
 60c:	7c cd 42 e6 	mftbu   r6
 610:	7f 9e 30 40 	cmplw   cr7,r30,r6
 614:	40 9e ff f0 	bne     cr7,604 <__c_kernel_clock_gettime+0x5c>
 618:	83 6b 00 28 	lwz     r27,40(r11)
 61c:	83 8b 00 2c 	lwz     r28,44(r11)
 620:	81 45 00 08 	lwz     r10,8(r5)
 624:	80 e5 00 0c 	lwz     r7,12(r5)
 628:	81 05 00 18 	lwz     r8,24(r5)
 62c:	83 e5 00 1c 	lwz     r31,28(r5)
 630:	80 cb 00 24 	lwz     r6,36(r11)
 634:	81 85 00 00 	lwz     r12,0(r5)
 638:	7f 8c 00 40 	cmplw   cr7,r12,r0
 63c:	40 9e 00 84 	bne     cr7,6c0 <__c_kernel_clock_gettime+0x118>

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
 arch/powerpc/include/asm/vdso/gettimeofday.h | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h
index d1e702e0ea86..c5a24f31382e 100644
--- a/arch/powerpc/include/asm/vdso/gettimeofday.h
+++ b/arch/powerpc/include/asm/vdso/gettimeofday.h
@@ -69,15 +69,18 @@ int clock_getres32_fallback(clockid_t _clkid, struct old_timespec32 *_ts)
 }
 #endif
 
-static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
+static __always_inline bool __arch_is_hw_counter_valid(s32 clock_mode)
 {
 	/*
 	 * clock_mode == 0 implies that vDSO are enabled otherwise
 	 * fallback on syscall.
 	 */
-	if (clock_mode != 0)
-		return U64_MAX;
+	return clock_mode == 0 ? true : false;
+}
+#define __arch_is_hw_counter_valid __arch_is_hw_counter_valid
 
+static __always_inline u64 __arch_get_hw_counter(s32 clock_mode)
+{
 	return get_tb();
 }
 
-- 
2.13.3


^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [RFC PATCH v3 06/12] lib: vdso: __iter_div_u64_rem() is suboptimal for 32 bit time
  2020-01-13 17:08 ` [RFC PATCH v3 06/12] lib: vdso: __iter_div_u64_rem() is suboptimal for 32 bit time Christophe Leroy
@ 2020-01-14 11:31   ` Thomas Gleixner
  0 siblings, 0 replies; 19+ messages in thread
From: Thomas Gleixner @ 2020-01-14 11:31 UTC (permalink / raw)
  To: Christophe Leroy, Benjamin Herrenschmidt, Paul Mackerras,
	Michael Ellerman, arnd, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

Christophe Leroy <christophe.leroy@c-s.fr> writes:

> Using __iter_div_ulong_rem() is suboptimal on 32 bits.
> Nanoseconds are only 32 bits, and VDSO data is updated every 10ms
> so nsec will never overflow 32 bits.

That's theory and perhaps true for bare metal, but there is no guarantee
on VIRT that the CPU which has the timekeeping duty assigned is not
scheduled out for longer than 4 seconds.

Thanks,

        tglx

^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer
  2020-01-13 17:08 ` [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer Christophe Leroy
@ 2020-01-14 23:06   ` Thomas Gleixner
  2020-01-15  6:15     ` Christophe Leroy
  0 siblings, 1 reply; 19+ messages in thread
From: Thomas Gleixner @ 2020-01-14 23:06 UTC (permalink / raw)
  To: Christophe Leroy, Benjamin Herrenschmidt, Paul Mackerras,
	Michael Ellerman, arnd, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86

Christophe Leroy <christophe.leroy@c-s.fr> writes:
>  
>  static __maybe_unused int
> +#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
> +__cvdso_clock_gettime_common(const struct vdso_data *vd, clockid_t clock,
> +		      struct __kernel_timespec *ts)
> +{
> +#else
>  __cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
>  {
>  	const struct vdso_data *vd = __arch_get_vdso_data();
> +#endif
>  	u32 msk;

If we do that, then there is no point in propagating this to the inner
functions. It's perfectly fine to have this distinction at the outermost
level.

As a related question, I noticed that you keep all that ASM voodoo in
the PPC specific code which provides the actual entry points. Is that
ASM code really still necessary? All current users of the generic VDSO
just do something like:

int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
{
        return __cvdso_clock_gettime(clock, ts);
}

in the architecture code. Is there a reason why this can't work on PPC?

Thanks,

        tglx

^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer
  2020-01-14 23:06   ` Thomas Gleixner
@ 2020-01-15  6:15     ` Christophe Leroy
  2020-01-16  9:16       ` Christophe Leroy
  0 siblings, 1 reply; 19+ messages in thread
From: Christophe Leroy @ 2020-01-15  6:15 UTC (permalink / raw)
  To: Thomas Gleixner, Benjamin Herrenschmidt, Paul Mackerras,
	Michael Ellerman, arnd, vincenzo.frascino, luto
  Cc: linux-kernel, linuxppc-dev, linux-arm-kernel, linux-mips, x86



Le 15/01/2020 à 00:06, Thomas Gleixner a écrit :
> Christophe Leroy <christophe.leroy@c-s.fr> writes:
>>   
>>   static __maybe_unused int
>> +#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
>> +__cvdso_clock_gettime_common(const struct vdso_data *vd, clockid_t clock,
>> +		      struct __kernel_timespec *ts)
>> +{
>> +#else
>>   __cvdso_clock_gettime_common(clockid_t clock, struct __kernel_timespec *ts)
>>   {
>>   	const struct vdso_data *vd = __arch_get_vdso_data();
>> +#endif
>>   	u32 msk;
> 
> If we do that, then there is no point in propagating this to the inner
> functions. It's perfectly fine to have this distinction at the outermost
> level.

In v2, I did it at the arch level (see 
https://patchwork.ozlabs.org/patch/1214983/). Andy was concerned about 
it being suboptimal for arches which (unlike powerpc) have PC related 
data addressing mode.

Wouldn't it be the same issue if doing it at the outermost level of 
generic VDSO ?

> 
> As a related question, I noticed that you keep all that ASM voodoo in
> the PPC specific code which provides the actual entry points. Is that
> ASM code really still necessary? All current users of the generic VDSO
> just do something like:
> 
> int __vdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
> {
>          return __cvdso_clock_gettime(clock, ts);
> }
> 
> in the architecture code. Is there a reason why this can't work on PPC?

The problem with powerpc is that VDSO functions have to (just like 
system calls) set the SO bit in CR register in case of error, or clear 
it if no error. There is no way to do that from the C function, because 
there is no way to tell GCC to not play up with CR register on function 
return.

Refer discussion at https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92769

Christophe

^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer
  2020-01-15  6:15     ` Christophe Leroy
@ 2020-01-16  9:16       ` Christophe Leroy
  2020-01-16 10:35         ` Thomas Gleixner
  0 siblings, 1 reply; 19+ messages in thread
From: Christophe Leroy @ 2020-01-16  9:16 UTC (permalink / raw)
  To: Thomas Gleixner, luto
  Cc: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	vincenzo.frascino, x86, linuxppc-dev, linux-kernel,
	linux-arm-kernel, linux-mips

Thomas, Andy,

Le 15/01/2020 à 07:15, Christophe Leroy a écrit :
> 
> 
> Le 15/01/2020 à 00:06, Thomas Gleixner a écrit :
>> Christophe Leroy <christophe.leroy@c-s.fr> writes:
>>>   static __maybe_unused int
>>> +#ifdef VDSO_GETS_VD_PTR_FROM_ARCH
>>> +__cvdso_clock_gettime_common(const struct vdso_data *vd, clockid_t 
>>> clock,
>>> +              struct __kernel_timespec *ts)
>>> +{
>>> +#else
>>>   __cvdso_clock_gettime_common(clockid_t clock, struct 
>>> __kernel_timespec *ts)
>>>   {
>>>       const struct vdso_data *vd = __arch_get_vdso_data();
>>> +#endif
>>>       u32 msk;
>>
>> If we do that, then there is no point in propagating this to the inner
>> functions. It's perfectly fine to have this distinction at the outermost
>> level.
> 
> In v2, I did it at the arch level (see 
> https://patchwork.ozlabs.org/patch/1214983/). Andy was concerned about 
> it being suboptimal for arches which (unlike powerpc) have PC related 
> data addressing mode.
> 
> Wouldn't it be the same issue if doing it at the outermost level of 
> generic VDSO ?

Any opinion on this ?

 From your point of view, what should I do:
A/ __arch_get_vdso_data() handled entirely at arch level and arches 
handing over the vdso data pointer to generic C VDSO functions all the 
time (as in my v2 series) ?
B/ Data pointer being handed over all the way up for arches wanting to 
do so, no changes at all for others (as in my v3 series) ?
C/ __arch_get_vdso_data() being called at the outermost generic level 
for arches not interested in handling data pointer from the caller (as 
suggested by Thomas) ?

Andy, with A/ you were concerned about arches being able to do PC 
related accesses. Would it be an issue for C/ as well ? If not, I guess 
C/ would be cleaner than B/ allthought not as clean as A which doesn't 
add any #ifdefery at all.

Thanks
Christophe

^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer
  2020-01-16  9:16       ` Christophe Leroy
@ 2020-01-16 10:35         ` Thomas Gleixner
  2020-01-16 20:22           ` Andy Lutomirski
  0 siblings, 1 reply; 19+ messages in thread
From: Thomas Gleixner @ 2020-01-16 10:35 UTC (permalink / raw)
  To: Christophe Leroy, luto
  Cc: Benjamin Herrenschmidt, Paul Mackerras, Michael Ellerman, arnd,
	vincenzo.frascino, x86, linuxppc-dev, linux-kernel,
	linux-arm-kernel, linux-mips

Christophe Leroy <christophe.leroy@c-s.fr> writes:
> Le 15/01/2020 à 07:15, Christophe Leroy a écrit :
>  From your point of view, what should I do:
> A/ __arch_get_vdso_data() handled entirely at arch level and arches 
> handing over the vdso data pointer to generic C VDSO functions all the 
> time (as in my v2 series) ?

No. That's again moving the same code to all architectures.

> B/ Data pointer being handed over all the way up for arches wanting to 
> do so, no changes at all for others (as in my v3 series) ?

Too much ifdeffery

> C/ __arch_get_vdso_data() being called at the outermost generic level 
> for arches not interested in handling data pointer from the caller (as 
> suggested by Thomas) ?
>
> Andy, with A/ you were concerned about arches being able to do PC 
> related accesses. Would it be an issue for C/ as well ? If not, I guess 
> C/ would be cleaner than B/ allthought not as clean as A which doesn't 
> add any #ifdefery at all.

You can avoid ifdeffery with C if you do:

static __maybe_unused int
__cvdso_data_clock_gettime(clockid_t clock, struct __kernel_timespec *ts,
                           const struct vdso_data *vd)
{
        .....
}

static __maybe_unused int
__cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
{
        const struct vdso_data *vd = __arch_get_vdso_data();

        return __cvdso_data_clock_gettime(clock, ts, vd);
}

and then use __cvdso_data_clock_gettime on PPC and let the other archs
unmodified.

Thanks,

        tglx

^ permalink raw reply	[flat|nested] 19+ messages in thread

* Re: [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer
  2020-01-16 10:35         ` Thomas Gleixner
@ 2020-01-16 20:22           ` Andy Lutomirski
  0 siblings, 0 replies; 19+ messages in thread
From: Andy Lutomirski @ 2020-01-16 20:22 UTC (permalink / raw)
  To: Thomas Gleixner
  Cc: Christophe Leroy, Andrew Lutomirski, Benjamin Herrenschmidt,
	Paul Mackerras, Michael Ellerman, Arnd Bergmann,
	Vincenzo Frascino, X86 ML, linuxppc-dev, LKML, linux-arm-kernel,
	open list:MIPS

On Thu, Jan 16, 2020 at 2:35 AM Thomas Gleixner <tglx@linutronix.de> wrote:
>
> static __maybe_unused int
> __cvdso_data_clock_gettime(clockid_t clock, struct __kernel_timespec *ts,
>                            const struct vdso_data *vd)
> {
>         .....
> }
>
> static __maybe_unused int
> __cvdso_clock_gettime(clockid_t clock, struct __kernel_timespec *ts)
> {
>         const struct vdso_data *vd = __arch_get_vdso_data();
>
>         return __cvdso_data_clock_gettime(clock, ts, vd);
> }
>
> and then use __cvdso_data_clock_gettime on PPC and let the other archs
> unmodified.
>
>

FWIW, I did some experiments on x86 with gcc 9.2.  gcc 9.2 uses
rip-relative accesses if I simplify the config enough and otherwise
materializes the pointer.  Presumably it decides that the code size
reduction is worth it if there are a lot of accesses.

I suspect that tglx's suggestion will be fine or at worst will add
negligible overhead on x86_64.

^ permalink raw reply	[flat|nested] 19+ messages in thread

end of thread, back to index

Thread overview: 19+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-01-13 17:08 [RFC PATCH v3 00/12] powerpc: switch VDSO to C implementation Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 01/12] powerpc/64: Don't provide time functions in compat VDSO32 Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 02/12] powerpc/vdso: Switch VDSO to generic C implementation Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 03/12] lib: vdso: mark __cvdso_clock_getres() as static Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 04/12] lib: vdso: inline do_hres() and do_coarse() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 05/12] lib: vdso: Avoid duplication in __cvdso_clock_getres() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 06/12] lib: vdso: __iter_div_u64_rem() is suboptimal for 32 bit time Christophe Leroy
2020-01-14 11:31   ` Thomas Gleixner
2020-01-13 17:08 ` [RFC PATCH v3 07/12] powerpc/vdso: simplify __get_datapage() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 08/12] lib: vdso: allow arches to provide vdso data pointer Christophe Leroy
2020-01-14 23:06   ` Thomas Gleixner
2020-01-15  6:15     ` Christophe Leroy
2020-01-16  9:16       ` Christophe Leroy
2020-01-16 10:35         ` Thomas Gleixner
2020-01-16 20:22           ` Andy Lutomirski
2020-01-13 17:08 ` [RFC PATCH v3 09/12] powerpc/vdso: provide inline alternative to __get_datapage() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 10/12] powerpc/vdso: provide vdso data pointer from the ASM caller Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 11/12] lib: vdso: split clock verification out of __arch_get_hw_counter() Christophe Leroy
2020-01-13 17:08 ` [RFC PATCH v3 12/12] powerpc/vdso: provide __arch_is_hw_counter_valid() Christophe Leroy

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