Take an effort to recode the arm64 vdso code from assembler to C previously submitted by Andrew Pinski <apin...@cavium.com>, rework it for use in both arm and arm64, overlapping any optimizations for each architecture. But instead of landing it in arm64, land the result into lib/vdso and unify both implementations to simplify future maintenance.
Move compiler-specific code to a local compiler.h file: - CONFIG_AEABI dependency check. - System call fallback functions standardized into a DEFINE_FALLBACK macro. - Replace arch_counter_get_cntvct() with arch_vdso_read_counter. - Deal with architecture specific unresolved references emitted by GCC. - Optimize handling of fallback calls in callers. - For time functions that always return success, do not waste time checking return value for switch to fallback. - Optimize unlikely nullptr checking in __vdso_gettimeofday, if tv null no need to proceed to fallback, as vdso is still capable of filling in the tv values. Signed-off-by: Mark Salyzyn <saly...@android.com> Tested-by: Mark Salyzyn <saly...@android.com> Cc: James Morse <james.mo...@arm.com> Cc: Russell King <li...@armlinux.org.uk> Cc: Catalin Marinas <catalin.mari...@arm.com> Cc: Will Deacon <will.dea...@arm.com> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Dmitry Safonov <dsafo...@virtuozzo.com> Cc: John Stultz <john.stu...@linaro.org> Cc: Mark Rutland <mark.rutl...@arm.com> Cc: Laura Abbott <labb...@redhat.com> Cc: Kees Cook <keesc...@chromium.org> Cc: Ard Biesheuvel <ard.biesheu...@linaro.org> Cc: Andy Gross <andy.gr...@linaro.org> Cc: Kevin Brodsky <kevin.brod...@arm.com> Cc: Andrew Pinski <apin...@cavium.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: linux-kernel@vger.kernel.org Cc: linux-arm-ker...@lists.infradead.org Cc: Jeremy Linton <jeremy.lin...@arm.com> Cc: android-ker...@android.com v2: - split first CL into 3 of 7 pieces v4: - switch to arch_vdso_read_counter as common API - update commit message to reflect overall reasoning v5: - comment about asm/arch_timer.h and asm/processor.h regarding why they have been added in compiler.h for porting clarity. - add linux/compiler.h in vgettimeofday.c because of notrace. - remove unnecessary dependency on linux/hrtimer.h --- arch/arm/vdso/compiler.h | 69 +++++++++++++++++++++ arch/arm/vdso/vgettimeofday.c | 109 +++++++++------------------------- 2 files changed, 96 insertions(+), 82 deletions(-) create mode 100644 arch/arm/vdso/compiler.h diff --git a/arch/arm/vdso/compiler.h b/arch/arm/vdso/compiler.h new file mode 100644 index 000000000000..af24502797e8 --- /dev/null +++ b/arch/arm/vdso/compiler.h @@ -0,0 +1,69 @@ +/* + * Userspace implementations of fallback calls + * + * Copyright (C) 2017 Cavium, Inc. + * Copyright (C) 2012 ARM Limited + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + * + * Author: Will Deacon <will.dea...@arm.com> + * Rewriten into C by: Andrew Pinski <apin...@cavium.com> + */ + +#ifndef __VDSO_COMPILER_H +#define __VDSO_COMPILER_H + +#include <asm/arch_timer.h> /* for arch_counter_get_cntvct() */ +#include <asm/processor.h> /* for cpu_relax() */ +#include <asm/unistd.h> +#include <linux/compiler.h> + +#ifndef CONFIG_AEABI +#error This code depends on AEABI system call conventions +#endif + +#define DEFINE_FALLBACK(name, type_arg1, name_arg1, type_arg2, name_arg2) \ +static notrace long name##_fallback(type_arg1 _##name_arg1, \ + type_arg2 _##name_arg2) \ +{ \ + register type_arg1 name_arg1 asm("r0") = _##name_arg1; \ + register type_arg2 name_arg2 asm("r1") = _##name_arg2; \ + register long ret asm ("r0"); \ + register long nr asm("r7") = __NR_##name; \ + \ + asm volatile( \ + " swi #0\n" \ + : "=r" (ret) \ + : "r" (name_arg1), "r" (name_arg2), "r" (nr) \ + : "memory"); \ + \ + return ret; \ +} + +#define arch_vdso_read_counter() arch_counter_get_cntvct() + +/* Avoid unresolved references emitted by GCC */ + +void __aeabi_unwind_cpp_pr0(void) +{ +} + +void __aeabi_unwind_cpp_pr1(void) +{ +} + +void __aeabi_unwind_cpp_pr2(void) +{ +} + +#endif /* __VDSO_COMPILER_H */ diff --git a/arch/arm/vdso/vgettimeofday.c b/arch/arm/vdso/vgettimeofday.c index 2474c17dc356..522094b147a2 100644 --- a/arch/arm/vdso/vgettimeofday.c +++ b/arch/arm/vdso/vgettimeofday.c @@ -22,21 +22,16 @@ * Reworked and rebased over arm version by: Mark Salyzyn <saly...@android.com> */ -#include <linux/compiler.h> -#include <linux/hrtimer.h> -#include <linux/time.h> -#include <asm/arch_timer.h> #include <asm/barrier.h> -#include <asm/bug.h> -#include <asm/page.h> -#include <asm/unistd.h> - -#ifndef CONFIG_AEABI -#error This code depends on AEABI system call conventions -#endif +#include <linux/compiler.h> /* for notrace */ +#include <linux/time.h> +#include "compiler.h" #include "datapage.h" +DEFINE_FALLBACK(gettimeofday, struct timeval *, tv, struct timezone *, tz) +DEFINE_FALLBACK(clock_gettime, clockid_t, clock, struct timespec *, ts) + static notrace u32 vdso_read_begin(const struct vdso_data *vd) { u32 seq; @@ -63,23 +58,6 @@ static notrace int vdso_read_retry(const struct vdso_data *vd, u32 start) return seq != start; } -static notrace long clock_gettime_fallback(clockid_t _clkid, - struct timespec *_ts) -{ - register struct timespec *ts asm("r1") = _ts; - register clockid_t clkid asm("r0") = _clkid; - register long ret asm ("r0"); - register long nr asm("r7") = __NR_clock_gettime; - - asm volatile( - " swi #0\n" - : "=r" (ret) - : "r" (clkid), "r" (ts), "r" (nr) - : "memory"); - - return ret; -} - static notrace int do_realtime_coarse(const struct vdso_data *vd, struct timespec *ts) { @@ -127,7 +105,7 @@ static notrace u64 get_ns(const struct vdso_data *vd) u64 cycle_now; u64 nsec; - cycle_now = arch_counter_get_cntvct(); + cycle_now = arch_vdso_read_counter(); cycle_delta = (cycle_now - vd->cs_cycle_last) & vd->cs_mask; @@ -200,85 +178,52 @@ static notrace int do_monotonic(const struct vdso_data *vd, struct timespec *ts) #endif /* CONFIG_ARM_ARCH_TIMER */ -notrace int __vdso_clock_gettime(clockid_t clkid, struct timespec *ts) +notrace int __vdso_clock_gettime(clockid_t clock, struct timespec *ts) { - int ret = -1; - const struct vdso_data *vd = __get_datapage(); - switch (clkid) { + switch (clock) { case CLOCK_REALTIME_COARSE: - ret = do_realtime_coarse(vd, ts); + do_realtime_coarse(vd, ts); break; case CLOCK_MONOTONIC_COARSE: - ret = do_monotonic_coarse(vd, ts); + do_monotonic_coarse(vd, ts); break; case CLOCK_REALTIME: - ret = do_realtime(vd, ts); + if (do_realtime(vd, ts)) + goto fallback; break; case CLOCK_MONOTONIC: - ret = do_monotonic(vd, ts); + if (do_monotonic(vd, ts)) + goto fallback; break; default: - break; + goto fallback; } - if (ret) - ret = clock_gettime_fallback(clkid, ts); - - return ret; -} - -static notrace long gettimeofday_fallback(struct timeval *_tv, - struct timezone *_tz) -{ - register struct timezone *tz asm("r1") = _tz; - register struct timeval *tv asm("r0") = _tv; - register long ret asm ("r0"); - register long nr asm("r7") = __NR_gettimeofday; - - asm volatile( - " swi #0\n" - : "=r" (ret) - : "r" (tv), "r" (tz), "r" (nr) - : "memory"); - - return ret; + return 0; +fallback: + return clock_gettime_fallback(clock, ts); } notrace int __vdso_gettimeofday(struct timeval *tv, struct timezone *tz) { - struct timespec ts; - int ret; - const struct vdso_data *vd = __get_datapage(); - ret = do_realtime(vd, &ts); - if (ret) - return gettimeofday_fallback(tv, tz); + if (likely(tv != NULL)) { + struct timespec ts; + + if (do_realtime(vd, &ts)) + return gettimeofday_fallback(tv, tz); - if (tv) { tv->tv_sec = ts.tv_sec; tv->tv_usec = ts.tv_nsec / 1000; } - if (tz) { + + if (unlikely(tz != NULL)) { tz->tz_minuteswest = vd->tz_minuteswest; tz->tz_dsttime = vd->tz_dsttime; } - return ret; -} - -/* Avoid unresolved references emitted by GCC */ - -void __aeabi_unwind_cpp_pr0(void) -{ -} - -void __aeabi_unwind_cpp_pr1(void) -{ -} - -void __aeabi_unwind_cpp_pr2(void) -{ + return 0; } -- 2.19.0.605.g01d371f741-goog
