From: Vincenzo Frascino <vincenzo.frascino@arm.com> To: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>, Catalin Marinas <catalin.marinas@arm.com>, Daniel Lezcano <daniel.lezcano@linaro.org>, Will Deacon <will.deacon@arm.com>, Russell King <linux@armlinux.org.uk>, Ralf Baechle <ralf@linux-mips.org>, Mark Salyzyn <salyzyn@android.com>, Paul Burton <paul.burton@mips.com>, Peter Collingbourne <pcc@google.com>, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v2 06/28] kernel: Define gettimeofday vdso common code Date: Tue, 11 Dec 2018 13:54:07 +0000 [thread overview] Message-ID: <97be4423-fb05-69a5-cd01-245e0ff29479@arm.com> (raw) In-Reply-To: <alpine.DEB.2.21.1811292230430.1657@nanos.tec.linutronix.de> On 29/11/2018 22:11, Thomas Gleixner wrote: > Vinzenco, > > On Thu, 29 Nov 2018, Vincenzo Frascino wrote: [...] >> +/* >> + * Returns the clock delta, in nanoseconds left-shifted by the clock >> + * shift. >> + */ >> +static __always_inline notrace u64 get_clock_shifted_nsec(u64 cycle_last, >> + u64 mult, >> + u64 mask) >> +{ >> + u64 res; >> + >> + /* Read the virtual counter. */ > > Virtual counter? No. That's again an ARM thingy. This needs to be done in > architecture code. > I agree, the name choice is unfortunate here. And I should have removed the comment as well. What this function does is getting the hardware counter, which seems not ARM specific. >> +/* >> + * This hook allows the architecture to validate the arguments >> + * passed to the library. >> + */ >> +#ifndef __HAVE_VDSO_ARCH_VALIDATE_ARG >> +#define __arch_valid_arg(x) true >> +#endif > > Why would you need that? There is really no point in adding architecture > hooks. > It is for the bogus. BTW I agree with your comment below. Will remove it in v3. >> +static notrace int __cvdso_clock_gettime(clockid_t clock, >> + struct __vdso_timespec *ts) >> +{ >> + const struct vdso_data *vd = __arch_get_vdso_data(); >> + >> + if (!__arch_valid_arg(ts)) > > Especially not for a timespec pointer. It's a user space supplied pointer > and what do you want to validate there? If it's bogus, access will fault, > end of story. >>> + return -EFAULT; >> + >> + switch (clock) { >> + case CLOCK_REALTIME: >> + if (do_realtime(vd, ts)) >> + goto fallback; >> + break; >> + case CLOCK_TAI: >> + if (do_tai(vd, ts)) >> + goto fallback; >> + break; >> + case CLOCK_MONOTONIC: >> + if (do_monotonic(vd, ts)) >> + goto fallback; >> + break; >> + case CLOCK_MONOTONIC_RAW: >> + if (do_monotonic_raw(vd, ts)) >> + goto fallback; >> + break; >> + case CLOCK_BOOTTIME: >> + if (do_boottime(vd, ts)) >> + goto fallback; >> + break; >> + case CLOCK_REALTIME_COARSE: >> + do_realtime_coarse(vd, ts); >> + break; >> + case CLOCK_MONOTONIC_COARSE: >> + do_monotonic_coarse(vd, ts); >> + break; > > See the x86 implementation. It avoids the switch case. The reason why you > want to avoid it is that the compiler will turn that thing above into a > call table, using an indirect branch and then requiring retpoline. > Thanks for providing the rationale here. Going forward I will generalize that implementation and make sure it works on all the architectures. [...] >> +static notrace int __cvdso_clock_getres(clockid_t clock_id, >> + struct __vdso_timespec *res) >> +{ >> + u64 ns; >> + >> + if (!__arch_valid_arg(res)) >> + return -EFAULT; >> + >> + if (clock_id == CLOCK_REALTIME || >> + clock_id == CLOCK_TAI || >> + clock_id == CLOCK_BOOTTIME || >> + clock_id == CLOCK_MONOTONIC || >> + clock_id == CLOCK_MONOTONIC_RAW) >> + ns = MONOTONIC_RES_NSEC; > > This is wrong. You cannot unconditionally set that. See what the syscall > based version does. You always need to verify that the syscall version and > the vdso version return the same information and not something randomly > different. > Agreed, I will fix it in v3. > Thanks, > > tglx > -- Regards, Vincenzo
WARNING: multiple messages have this Message-ID (diff)
From: Vincenzo Frascino <vincenzo.frascino@arm.com> To: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will.deacon@arm.com>, Arnd Bergmann <arnd@arndb.de>, Russell King <linux@armlinux.org.uk>, Ralf Baechle <ralf@linux-mips.org>, Paul Burton <paul.burton@mips.com>, Daniel Lezcano <daniel.lezcano@linaro.org>, Mark Salyzyn <salyzyn@android.com>, Peter Collingbourne <pcc@google.com> Subject: Re: [PATCH v2 06/28] kernel: Define gettimeofday vdso common code Date: Tue, 11 Dec 2018 13:54:07 +0000 [thread overview] Message-ID: <97be4423-fb05-69a5-cd01-245e0ff29479@arm.com> (raw) Message-ID: <20181211135407.DUheiTJ3axlIcnsuK2avEtOhGK87n9vstYZZtad6GGI@z> (raw) In-Reply-To: <alpine.DEB.2.21.1811292230430.1657@nanos.tec.linutronix.de> On 29/11/2018 22:11, Thomas Gleixner wrote: > Vinzenco, > > On Thu, 29 Nov 2018, Vincenzo Frascino wrote: [...] >> +/* >> + * Returns the clock delta, in nanoseconds left-shifted by the clock >> + * shift. >> + */ >> +static __always_inline notrace u64 get_clock_shifted_nsec(u64 cycle_last, >> + u64 mult, >> + u64 mask) >> +{ >> + u64 res; >> + >> + /* Read the virtual counter. */ > > Virtual counter? No. That's again an ARM thingy. This needs to be done in > architecture code. > I agree, the name choice is unfortunate here. And I should have removed the comment as well. What this function does is getting the hardware counter, which seems not ARM specific. >> +/* >> + * This hook allows the architecture to validate the arguments >> + * passed to the library. >> + */ >> +#ifndef __HAVE_VDSO_ARCH_VALIDATE_ARG >> +#define __arch_valid_arg(x) true >> +#endif > > Why would you need that? There is really no point in adding architecture > hooks. > It is for the bogus. BTW I agree with your comment below. Will remove it in v3. >> +static notrace int __cvdso_clock_gettime(clockid_t clock, >> + struct __vdso_timespec *ts) >> +{ >> + const struct vdso_data *vd = __arch_get_vdso_data(); >> + >> + if (!__arch_valid_arg(ts)) > > Especially not for a timespec pointer. It's a user space supplied pointer > and what do you want to validate there? If it's bogus, access will fault, > end of story. >>> + return -EFAULT; >> + >> + switch (clock) { >> + case CLOCK_REALTIME: >> + if (do_realtime(vd, ts)) >> + goto fallback; >> + break; >> + case CLOCK_TAI: >> + if (do_tai(vd, ts)) >> + goto fallback; >> + break; >> + case CLOCK_MONOTONIC: >> + if (do_monotonic(vd, ts)) >> + goto fallback; >> + break; >> + case CLOCK_MONOTONIC_RAW: >> + if (do_monotonic_raw(vd, ts)) >> + goto fallback; >> + break; >> + case CLOCK_BOOTTIME: >> + if (do_boottime(vd, ts)) >> + goto fallback; >> + break; >> + case CLOCK_REALTIME_COARSE: >> + do_realtime_coarse(vd, ts); >> + break; >> + case CLOCK_MONOTONIC_COARSE: >> + do_monotonic_coarse(vd, ts); >> + break; > > See the x86 implementation. It avoids the switch case. The reason why you > want to avoid it is that the compiler will turn that thing above into a > call table, using an indirect branch and then requiring retpoline. > Thanks for providing the rationale here. Going forward I will generalize that implementation and make sure it works on all the architectures. [...] >> +static notrace int __cvdso_clock_getres(clockid_t clock_id, >> + struct __vdso_timespec *res) >> +{ >> + u64 ns; >> + >> + if (!__arch_valid_arg(res)) >> + return -EFAULT; >> + >> + if (clock_id == CLOCK_REALTIME || >> + clock_id == CLOCK_TAI || >> + clock_id == CLOCK_BOOTTIME || >> + clock_id == CLOCK_MONOTONIC || >> + clock_id == CLOCK_MONOTONIC_RAW) >> + ns = MONOTONIC_RES_NSEC; > > This is wrong. You cannot unconditionally set that. See what the syscall > based version does. You always need to verify that the syscall version and > the vdso version return the same information and not something randomly > different. > Agreed, I will fix it in v3. > Thanks, > > tglx > -- Regards, Vincenzo
next prev parent reply other threads:[~2018-12-11 13:54 UTC|newest] Thread overview: 100+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-11-29 17:05 [PATCH v2 00/28] Unify vDSOs across more architectures Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 01/28] kernel: Standardize vdso_datapage Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 22:39 ` Thomas Gleixner 2018-11-29 22:39 ` Thomas Gleixner 2018-12-11 13:22 ` Vincenzo Frascino 2018-12-11 13:22 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 02/28] kernel: Add Monotonic boot time support Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 03/28] kernel: Add International Atomic Time support Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 04/28] kernel: Add masks support for Raw and NTP time Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 22:41 ` Thomas Gleixner 2018-11-29 22:41 ` Thomas Gleixner 2018-12-11 13:24 ` Vincenzo Frascino 2018-12-11 13:24 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 05/28] kernel: Add clock_mode support Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 06/28] kernel: Define gettimeofday vdso common code Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 20:42 ` Arnd Bergmann 2018-11-29 20:42 ` Arnd Bergmann 2018-12-11 13:39 ` Vincenzo Frascino 2018-12-11 13:39 ` Vincenzo Frascino 2018-12-11 21:41 ` Arnd Bergmann 2018-12-11 21:41 ` Arnd Bergmann 2018-12-13 9:46 ` Vincenzo Frascino 2018-12-13 9:46 ` Vincenzo Frascino 2018-11-29 22:11 ` Thomas Gleixner 2018-11-29 22:11 ` Thomas Gleixner 2018-11-30 14:29 ` Arnd Bergmann 2018-11-30 14:29 ` Arnd Bergmann 2018-12-11 14:02 ` Vincenzo Frascino 2018-12-11 14:02 ` Vincenzo Frascino 2018-12-07 17:53 ` Will Deacon 2018-12-07 17:53 ` Will Deacon 2019-02-08 17:35 ` Will Deacon 2019-02-08 17:35 ` Will Deacon 2019-02-08 19:28 ` Thomas Gleixner 2019-02-08 19:28 ` Thomas Gleixner 2019-02-08 19:30 ` Thomas Gleixner 2019-02-08 19:30 ` Thomas Gleixner 2019-02-13 17:04 ` Will Deacon 2019-02-13 17:04 ` Will Deacon 2019-02-13 19:35 ` Thomas Gleixner 2019-02-13 19:35 ` Thomas Gleixner 2019-02-13 17:05 ` Will Deacon 2019-02-13 17:05 ` Will Deacon 2018-12-11 13:54 ` Vincenzo Frascino [this message] 2018-12-11 13:54 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 07/28] arm64: Build vDSO with -ffixed-x18 Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 08/28] arm64: Substitute gettimeofday with C implementation Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 09/28] arm64: compat: Alloc separate pages for vectors and sigpage Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 10/28] arm64: compat: Split kuser32 Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 11/28] arm64: compat: Refactor aarch32_alloc_vdso_pages() Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 12/28] arm64: compat: Add KUSER_HELPERS config option Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 13/28] arm64: compat: Add missing syscall numbers Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 14/28] arm64: compat: Expose signal related structures Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 15/28] arm64: compat: Generate asm offsets for signals Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 16/28] lib: vdso: Add compat support Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 17/28] arm64: compat: Add vDSO Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 18/28] arm64: Refactor vDSO code Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 19/28] arm64: compat: vDSO setup for compat layer Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 20/28] arm64: elf: vDSO code page discovery Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 21/28] arm64: compat: Get sigreturn trampolines from vDSO Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 22/28] arm64: Add vDSO compat support Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 23/28] arm64: Enable compat vDSO support Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 24/28] arm: Add support for generic vDSO Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-12-10 22:13 ` Mark Salyzyn 2018-12-10 22:13 ` Mark Salyzyn 2018-12-11 14:15 ` Vincenzo Frascino 2018-12-11 14:15 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 25/28] mips: Introduce vdso_direct Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 26/28] clock: csrc-4k: Add support for vdso_direct Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 27/28] clock: gic-timer: " Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino 2018-11-29 17:05 ` [PATCH v2 28/28] mips: Add support for generic vDSO Vincenzo Frascino 2018-11-29 17:05 ` Vincenzo Frascino
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