From ce7d8056e38b770f070fc4499c577322b6ccb9c7 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Fri, 27 Nov 2020 00:10:03 +1100 Subject: [PATCH] powerpc/vdso: Prepare for switching VDSO to generic C implementation. Prepare for switching VDSO to generic C implementation in following patch. Here, we: - Prepare the helpers to call the C VDSO functions - Prepare the required callbacks for the C VDSO functions - Prepare the clocksource.h files to define VDSO_ARCH_CLOCKMODES - Add the C trampolines to the generic C VDSO functions 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. Implementing __arch_get_vdso_data() would clobber 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. Implement __arch_vdso_capable() and always return true. Provide vdso_shift_ns(), as the generic x >> s gives the following bad result: 18: 35 25 ff e0 addic. r9,r5,-32 1c: 41 80 00 10 blt 2c 20: 7c 64 4c 30 srw r4,r3,r9 24: 38 60 00 00 li r3,0 ... 2c: 54 69 08 3c rlwinm r9,r3,1,0,30 30: 21 45 00 1f subfic r10,r5,31 34: 7c 84 2c 30 srw r4,r4,r5 38: 7d 29 50 30 slw r9,r9,r10 3c: 7c 63 2c 30 srw r3,r3,r5 40: 7d 24 23 78 or r4,r9,r4 In our case the shift is always <= 32. In addition, the upper 32 bits of the result are likely nul. Lets GCC know it, it also optimises the following calculations. With the patch, we get: 0: 21 25 00 20 subfic r9,r5,32 4: 7c 69 48 30 slw r9,r3,r9 8: 7c 84 2c 30 srw r4,r4,r5 c: 7d 24 23 78 or r4,r9,r4 10: 7c 63 2c 30 srw r3,r3,r5 Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201126131006.2431205-6-mpe@ellerman.id.au --- arch/powerpc/include/asm/clocksource.h | 7 + arch/powerpc/include/asm/ppc_asm.h | 2 + arch/powerpc/include/asm/vdso/clocksource.h | 7 + arch/powerpc/include/asm/vdso/gettimeofday.h | 187 +++++++++++++++++++++++++++ arch/powerpc/kernel/vdso32/vgettimeofday.c | 28 ++++ arch/powerpc/kernel/vdso64/vgettimeofday.c | 29 +++++ 6 files changed, 260 insertions(+) create mode 100644 arch/powerpc/include/asm/clocksource.h create mode 100644 arch/powerpc/include/asm/vdso/clocksource.h create mode 100644 arch/powerpc/include/asm/vdso/gettimeofday.h create mode 100644 arch/powerpc/kernel/vdso32/vgettimeofday.c create mode 100644 arch/powerpc/kernel/vdso64/vgettimeofday.c diff --git a/arch/powerpc/include/asm/clocksource.h b/arch/powerpc/include/asm/clocksource.h new file mode 100644 index 0000000..0a26ef1 --- /dev/null +++ b/arch/powerpc/include/asm/clocksource.h @@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_POWERPC_CLOCKSOURCE_H +#define _ASM_POWERPC_CLOCKSOURCE_H + +#include + +#endif /* _ASM_POWERPC_CLOCKSOURCE_H */ diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h index 101986d..cfa8148 100644 --- a/arch/powerpc/include/asm/ppc_asm.h +++ b/arch/powerpc/include/asm/ppc_asm.h @@ -251,6 +251,8 @@ n: #define _GLOBAL_TOC(name) _GLOBAL(name) +#define DOTSYM(a) a + #endif /* diff --git a/arch/powerpc/include/asm/vdso/clocksource.h b/arch/powerpc/include/asm/vdso/clocksource.h new file mode 100644 index 0000000..c1ba56b --- /dev/null +++ b/arch/powerpc/include/asm/vdso/clocksource.h @@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_POWERPC_VDSO_CLOCKSOURCE_H +#define _ASM_POWERPC_VDSO_CLOCKSOURCE_H + +#define VDSO_ARCH_CLOCKMODES VDSO_CLOCKMODE_ARCHTIMER + +#endif diff --git a/arch/powerpc/include/asm/vdso/gettimeofday.h b/arch/powerpc/include/asm/vdso/gettimeofday.h new file mode 100644 index 0000000..43dd1dc --- /dev/null +++ b/arch/powerpc/include/asm/vdso/gettimeofday.h @@ -0,0 +1,187 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _ASM_POWERPC_VDSO_GETTIMEOFDAY_H +#define _ASM_POWERPC_VDSO_GETTIMEOFDAY_H + +#ifdef __ASSEMBLY__ + +#include + +/* + * The macros sets two stack frames, one for the caller and one for the callee + * because there are no requirement for the caller to set a stack frame when + * calling VDSO so it may have omitted to set one, especially on PPC64 + */ + +.macro cvdso_call funct + .cfi_startproc + PPC_STLU r1, -PPC_MIN_STKFRM(r1) + mflr r0 + .cfi_register lr, r0 + PPC_STLU r1, -PPC_MIN_STKFRM(r1) + PPC_STL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1) + get_datapage r5, r0 + addi r5, r5, VDSO_DATA_OFFSET + bl DOTSYM(\funct) + PPC_LL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1) + cmpwi r3, 0 + mtlr r0 + .cfi_restore lr + addi r1, r1, 2 * PPC_MIN_STKFRM + crclr so + beqlr+ + crset so + neg r3, r3 + blr + .cfi_endproc +.endm + +.macro cvdso_call_time funct + .cfi_startproc + PPC_STLU r1, -PPC_MIN_STKFRM(r1) + mflr r0 + .cfi_register lr, r0 + PPC_STLU r1, -PPC_MIN_STKFRM(r1) + PPC_STL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1) + get_datapage r4, r0 + addi r4, r4, VDSO_DATA_OFFSET + bl DOTSYM(\funct) + PPC_LL r0, PPC_MIN_STKFRM + PPC_LR_STKOFF(r1) + crclr so + mtlr r0 + .cfi_restore lr + addi r1, r1, 2 * PPC_MIN_STKFRM + blr + .cfi_endproc +.endm + +#else + +#include +#include +#include +#include + +#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" (r4), "+r" (r0) + : "r" (r3) + : "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 BUILD_VDSO32 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, + const struct vdso_data *vd) +{ + return get_tb(); +} + +const struct vdso_data *__arch_get_vdso_data(void); + +static inline bool vdso_clocksource_ok(const struct vdso_data *vd) +{ + return true; +} +#define vdso_clocksource_ok vdso_clocksource_ok + +/* + * 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 + +#ifndef __powerpc64__ +static __always_inline u64 vdso_shift_ns(u64 ns, unsigned long shift) +{ + u32 hi = ns >> 32; + u32 lo = ns; + + lo >>= shift; + lo |= hi << (32 - shift); + hi >>= shift; + + if (likely(hi == 0)) + return lo; + + return ((u64)hi << 32) | lo; +} +#define vdso_shift_ns vdso_shift_ns +#endif + +#ifdef __powerpc64__ +int __c_kernel_clock_gettime(clockid_t clock, struct __kernel_timespec *ts, + const struct vdso_data *vd); +int __c_kernel_clock_getres(clockid_t clock_id, struct __kernel_timespec *res, + const struct vdso_data *vd); +#else +int __c_kernel_clock_gettime(clockid_t clock, struct old_timespec32 *ts, + const struct vdso_data *vd); +int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res, + const struct vdso_data *vd); +#endif +int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz, + const struct vdso_data *vd); +__kernel_old_time_t __c_kernel_time(__kernel_old_time_t *time, + const struct vdso_data *vd); +#endif /* __ASSEMBLY__ */ + +#endif /* _ASM_POWERPC_VDSO_GETTIMEOFDAY_H */ diff --git a/arch/powerpc/kernel/vdso32/vgettimeofday.c b/arch/powerpc/kernel/vdso32/vgettimeofday.c new file mode 100644 index 0000000..0d4bc21 --- /dev/null +++ b/arch/powerpc/kernel/vdso32/vgettimeofday.c @@ -0,0 +1,28 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Powerpc userspace implementations of gettimeofday() and similar. + */ +#include + +int __c_kernel_clock_gettime(clockid_t clock, struct old_timespec32 *ts, + const struct vdso_data *vd) +{ + return __cvdso_clock_gettime32_data(vd, clock, ts); +} + +int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz, + const struct vdso_data *vd) +{ + return __cvdso_gettimeofday_data(vd, tv, tz); +} + +int __c_kernel_clock_getres(clockid_t clock_id, struct old_timespec32 *res, + const struct vdso_data *vd) +{ + return __cvdso_clock_getres_time32_data(vd, clock_id, res); +} + +__kernel_old_time_t __c_kernel_time(__kernel_old_time_t *time, const struct vdso_data *vd) +{ + return __cvdso_time_data(vd, time); +} diff --git a/arch/powerpc/kernel/vdso64/vgettimeofday.c b/arch/powerpc/kernel/vdso64/vgettimeofday.c new file mode 100644 index 0000000..5b55000 --- /dev/null +++ b/arch/powerpc/kernel/vdso64/vgettimeofday.c @@ -0,0 +1,29 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Powerpc userspace implementations of gettimeofday() and similar. + */ +#include +#include + +int __c_kernel_clock_gettime(clockid_t clock, struct __kernel_timespec *ts, + const struct vdso_data *vd) +{ + return __cvdso_clock_gettime_data(vd, clock, ts); +} + +int __c_kernel_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz, + const struct vdso_data *vd) +{ + return __cvdso_gettimeofday_data(vd, tv, tz); +} + +int __c_kernel_clock_getres(clockid_t clock_id, struct __kernel_timespec *res, + const struct vdso_data *vd) +{ + return __cvdso_clock_getres_data(vd, clock_id, res); +} + +__kernel_old_time_t __c_kernel_time(__kernel_old_time_t *time, const struct vdso_data *vd) +{ + return __cvdso_time_data(vd, time); +} -- 2.7.4