Re: [PATCH OLK-6.6 1/2] arm64: arch_timer: Disable CNTVCT_EL0 trap if workaround is enabled

On 2023/12/4 10:27, Yang Yingliang wrote:

hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/I8LFBU CVE: NA

---

It costs very much time to read CNTVCT_EL0, if a cntvct workaround and CNTVCT_EL0 trap is enabled. To decrease the read time, we disable CNTVCT_EL0 trap, introduce vdso_fix and vdso_shift for doing cntvct workaround in VDSO.

Signed-off-by: Yang Yingliang yangyingliang@huawei.com Reviewed-by: Hanjun Guo guohanjun@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com

这个要移除掉，只保留第一个；

. 下面的strncmp strlen是不是太重了 可以直接判断 wa->read_cntvct_el0 是否跟hisi_161010101_read_cntvct_el0相等吧；

---

drivers/clocksource/arm_arch_timer.c | 20 +++++++++++++++++--- include/linux/clocksource.h | 2 ++ include/vdso/datapage.h | 6 ++++-- kernel/time/vsyscall.c | 8 ++++++++ 4 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c index 071b04f1ee73..f47b2a59020f 100644 --- a/drivers/clocksource/arm_arch_timer.c +++ b/drivers/clocksource/arm_arch_timer.c @@ -92,6 +92,8 @@ static enum vdso_clock_mode vdso_default = VDSO_CLOCKMODE_ARCHTIMER; #else static enum vdso_clock_mode vdso_default = VDSO_CLOCKMODE_NONE; #endif /* CONFIG_GENERIC_GETTIMEOFDAY */ +static bool vdso_fix; +static u16 vdso_shift;

static cpumask_t evtstrm_available = CPU_MASK_NONE; static bool evtstrm_enable __ro_after_init = IS_ENABLED(CONFIG_ARM_ARCH_TIMER_EVTSTREAM); @@ -599,8 +601,18 @@ void arch_timer_enable_workaround(const struct arch_timer_erratum_workaround *wa * change both the default value and the vdso itself. */ if (wa->read_cntvct_el0) {

• clocksource_counter.vdso_clock_mode = VDSO_CLOCKMODE_NONE;
  

• vdso_default = VDSO_CLOCKMODE_NONE;
  

• if (!strncmp(wa->desc, "HiSilicon erratum 161010101",
  

• 	     strlen("HiSilicon erratum 161010101"))) {
  

• 	vdso_fix = true;
  

• 	vdso_shift = 5;
  

• } else if (!strncmp(wa->desc, "Freescale erratum a005858",
  

• 		    strlen("Freescale erratum a005858"))) {
  

• 	vdso_fix = true;
  

• 	vdso_shift = 0;
  

• } else {
  

• 	clocksource_counter.vdso_clock_mode = VDSO_CLOCKMODE_NONE;
  

• 	vdso_default = VDSO_CLOCKMODE_NONE;
  

• }
  

  } else if (wa->disable_compat_vdso && vdso_default != VDSO_CLOCKMODE_NONE) { vdso_default = VDSO_CLOCKMODE_ARCHTIMER_NOCOMPAT; clocksource_counter.vdso_clock_mode = vdso_default;

@@ -973,7 +985,7 @@ static void arch_counter_set_user_access(void) * need to be workaround. The vdso may have been already * disabled though. */

• if (arch_timer_this_cpu_has_cntvct_wa())

• if (arch_timer_this_cpu_has_cntvct_wa() && !vdso_fix) pr_info("CPU%d: Trapping CNTVCT access\n", smp_processor_id()); else cntkctl |= ARCH_TIMER_USR_VCT_ACCESS_EN;

@@ -1129,6 +1141,8 @@ static void __init arch_counter_register(unsigned type)

arch_timer_read_counter = rd;
clocksource_counter.vdso_clock_mode = vdso_default;

• clocksource_counter.vdso_fix = vdso_fix;
  

• clocksource_counter.vdso_shift = vdso_shift;
  

  } else { arch_timer_read_counter = arch_counter_get_cntvct_mem; scr = arch_counter_get_cntvct_mem;

diff --git a/include/linux/clocksource.h b/include/linux/clocksource.h index 1d42d4b17327..e23eea881d0f 100644 --- a/include/linux/clocksource.h +++ b/include/linux/clocksource.h @@ -110,6 +110,8 @@ struct clocksource { int rating; enum clocksource_ids id; enum vdso_clock_mode vdso_clock_mode;

• u16 vdso_fix;

• u16 vdso_shift; unsigned long flags;

  int (*enable)(struct clocksource *cs);

diff --git a/include/vdso/datapage.h b/include/vdso/datapage.h index 73eb622e7663..6bbca70342f3 100644 --- a/include/vdso/datapage.h +++ b/include/vdso/datapage.h @@ -69,7 +69,8 @@ struct vdso_timestamp {

• @tz_minuteswest: minutes west of Greenwich
• @tz_dsttime: type of DST correction
• @hrtimer_res: hrtimer resolution

• • @__unused: unused

• • @vdso_fix: avoid the clock bug in VDSO
• • @vdso_shift: count of bit to be ignored
  • @arch_data: architecture specific data (optional, defaults

  • 	to an empty struct)
    

@@ -104,7 +105,8 @@ struct vdso_data { s32 tz_minuteswest; s32 tz_dsttime; u32 hrtimer_res;

• u32 __unused;

• u16 vdso_fix;

• u16 vdso_shift;

  struct arch_vdso_data arch_data; };

diff --git a/kernel/time/vsyscall.c b/kernel/time/vsyscall.c index f0d5062d9cbc..8045de999586 100644 --- a/kernel/time/vsyscall.c +++ b/kernel/time/vsyscall.c @@ -74,14 +74,22 @@ void update_vsyscall(struct timekeeper *tk) struct vdso_data *vdata = __arch_get_k_vdso_data(); struct vdso_timestamp *vdso_ts; s32 clock_mode;

• u16 vdso_fix;

• u16 vdso_shift; u64 nsec;

  /* copy vsyscall data */ vdso_write_begin(vdata);

  clock_mode = tk->tkr_mono.clock->vdso_clock_mode;

• vdso_fix = tk->tkr_mono.clock->vdso_fix;

• vdso_shift = tk->tkr_mono.clock->vdso_shift; vdata[CS_HRES_COARSE].clock_mode = clock_mode;

• vdata[CS_HRES_COARSE].vdso_fix = vdso_fix;

• vdata[CS_HRES_COARSE].vdso_shift = vdso_shift; vdata[CS_RAW].clock_mode = clock_mode;

• vdata[CS_RAW].vdso_fix = vdso_fix;

• vdata[CS_RAW].vdso_shift = vdso_shift;

  /* CLOCK_REALTIME also required for time() */ vdso_ts = &vdata[CS_HRES_COARSE].basetime[CLOCK_REALTIME];