Commit ce7d8056 authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman

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 <shift+0x14>
  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: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20201126131006.2431205-6-mpe@ellerman.id.au
parent 1f1676bb
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_POWERPC_CLOCKSOURCE_H
#define _ASM_POWERPC_CLOCKSOURCE_H
#include <asm/vdso/clocksource.h>
#endif /* _ASM_POWERPC_CLOCKSOURCE_H */
......@@ -251,6 +251,8 @@ GLUE(.,name):
#define _GLOBAL_TOC(name) _GLOBAL(name)
#define DOTSYM(a) a
#endif
/*
......
/* 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
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_POWERPC_VDSO_GETTIMEOFDAY_H
#define _ASM_POWERPC_VDSO_GETTIMEOFDAY_H
#ifdef __ASSEMBLY__
#include <asm/ppc_asm.h>
/*
* 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 <asm/vdso/timebase.h>
#include <asm/barrier.h>
#include <asm/unistd.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" (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 */
// SPDX-License-Identifier: GPL-2.0
/*
* Powerpc userspace implementations of gettimeofday() and similar.
*/
#include <linux/types.h>
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);
}
// 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,
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);
}
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment