October 2019 - Linux-stable-mirror

[tip: x86/urgent] x86/asm: Fix MWAITX C-state hint value

by tip-bot2 for Janakarajan Natarajan

The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 9b69cab42e5d14b8f0467566e3d97e682365db2d Gitweb: https://git.kernel.org/tip/9b69cab42e5d14b8f0467566e3d97e682365db2d Author: Janakarajan Natarajan <Janakarajan.Natarajan(a)amd.com> AuthorDate: Mon, 07 Oct 2019 19:00:22 Committer: Borislav Petkov <bp(a)suse.de> CommitterDate: Tue, 08 Oct 2019 09:48:09 +02:00 x86/asm: Fix MWAITX C-state hint value As per "AMD64 Architecture Programmer's Manual Volume 3: General-Purpose and System Instructions", MWAITX EAX[7:4]+1 specifies the optional hint of the optimized C-state. For C0 state, EAX[7:4] should be set to 0xf. Currently, a value of 0xf is set for EAX[3:0] instead of EAX[7:4]. Fix this by changing MWAITX_DISABLE_CSTATES from 0xf to 0xf0. This hasn't had any implications so far because setting reserved bits in EAX is simply ignored by the CPU. [ bp: Fixup comment in delay_mwaitx() and massage. ] Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan(a)amd.com> Signed-off-by: Borislav Petkov <bp(a)suse.de> Cc: Frederic Weisbecker <frederic(a)kernel.org> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: "H. Peter Anvin" <hpa(a)zytor.com> Cc: Ingo Molnar <mingo(a)redhat.com> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: "x86(a)kernel.org" <x86(a)kernel.org> Cc: Zhenzhong Duan <zhenzhong.duan(a)oracle.com> Cc: <stable(a)vger.kernel.org> Link: https://lkml.kernel.org/r/20191007190011.4859-1-Janakarajan.Natarajan@amd.c… --- arch/x86/include/asm/mwait.h | 2 +- arch/x86/lib/delay.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h index e28f8b7..9d5252c 100644 --- a/arch/x86/include/asm/mwait.h +++ b/arch/x86/include/asm/mwait.h @@ -21,7 +21,7 @@ #define MWAIT_ECX_INTERRUPT_BREAK 0x1 #define MWAITX_ECX_TIMER_ENABLE BIT(1) #define MWAITX_MAX_LOOPS ((u32)-1) -#define MWAITX_DISABLE_CSTATES 0xf +#define MWAITX_DISABLE_CSTATES 0xf0 static inline void __monitor(const void *eax, unsigned long ecx, unsigned long edx) diff --git a/arch/x86/lib/delay.c b/arch/x86/lib/delay.c index b7375dc..c126571 100644 --- a/arch/x86/lib/delay.c +++ b/arch/x86/lib/delay.c @@ -113,8 +113,8 @@ static void delay_mwaitx(unsigned long __loops) __monitorx(raw_cpu_ptr(&cpu_tss_rw), 0, 0); /* - * AMD, like Intel, supports the EAX hint and EAX=0xf - * means, do not enter any deep C-state and we use it + * AMD, like Intel's MWAIT version, supports the EAX hint and + * EAX=0xf0 means, do not enter any deep C-state and we use it * here in delay() to minimize wakeup latency. */ __mwaitx(MWAITX_DISABLE_CSTATES, delay, MWAITX_ECX_TIMER_ENABLE);

5 years, 3 months

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[tip: x86/urgent] x86/asm: Fix MWAITX C-state hint value

by tip-bot2 for Janakarajan Natarajan

The following commit has been merged into the x86/urgent branch of tip: Commit-ID: 9b69cab42e5d14b8f0467566e3d97e682365db2d Gitweb: https://git.kernel.org/tip/9b69cab42e5d14b8f0467566e3d97e682365db2d Author: Janakarajan Natarajan <Janakarajan.Natarajan(a)amd.com> AuthorDate: Mon, 07 Oct 2019 19:00:22 Committer: Borislav Petkov <bp(a)suse.de> CommitterDate: Tue, 08 Oct 2019 09:48:09 +02:00 x86/asm: Fix MWAITX C-state hint value As per "AMD64 Architecture Programmer's Manual Volume 3: General-Purpose and System Instructions", MWAITX EAX[7:4]+1 specifies the optional hint of the optimized C-state. For C0 state, EAX[7:4] should be set to 0xf. Currently, a value of 0xf is set for EAX[3:0] instead of EAX[7:4]. Fix this by changing MWAITX_DISABLE_CSTATES from 0xf to 0xf0. This hasn't had any implications so far because setting reserved bits in EAX is simply ignored by the CPU. [ bp: Fixup comment in delay_mwaitx() and massage. ] Signed-off-by: Janakarajan Natarajan <Janakarajan.Natarajan(a)amd.com> Signed-off-by: Borislav Petkov <bp(a)suse.de> Cc: Frederic Weisbecker <frederic(a)kernel.org> Cc: Greg Kroah-Hartman <gregkh(a)linuxfoundation.org> Cc: "H. Peter Anvin" <hpa(a)zytor.com> Cc: Ingo Molnar <mingo(a)redhat.com> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: "x86(a)kernel.org" <x86(a)kernel.org> Cc: Zhenzhong Duan <zhenzhong.duan(a)oracle.com> Cc: <stable(a)vger.kernel.org> Link: https://lkml.kernel.org/r/20191007190011.4859-1-Janakarajan.Natarajan@amd.c… --- arch/x86/include/asm/mwait.h | 2 +- arch/x86/lib/delay.c | 4 ++-- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/x86/include/asm/mwait.h b/arch/x86/include/asm/mwait.h index e28f8b7..9d5252c 100644 --- a/arch/x86/include/asm/mwait.h +++ b/arch/x86/include/asm/mwait.h @@ -21,7 +21,7 @@ #define MWAIT_ECX_INTERRUPT_BREAK 0x1 #define MWAITX_ECX_TIMER_ENABLE BIT(1) #define MWAITX_MAX_LOOPS ((u32)-1) -#define MWAITX_DISABLE_CSTATES 0xf +#define MWAITX_DISABLE_CSTATES 0xf0 static inline void __monitor(const void *eax, unsigned long ecx, unsigned long edx) diff --git a/arch/x86/lib/delay.c b/arch/x86/lib/delay.c index b7375dc..c126571 100644 --- a/arch/x86/lib/delay.c +++ b/arch/x86/lib/delay.c @@ -113,8 +113,8 @@ static void delay_mwaitx(unsigned long __loops) __monitorx(raw_cpu_ptr(&cpu_tss_rw), 0, 0); /* - * AMD, like Intel, supports the EAX hint and EAX=0xf - * means, do not enter any deep C-state and we use it + * AMD, like Intel's MWAIT version, supports the EAX hint and + * EAX=0xf0 means, do not enter any deep C-state and we use it * here in delay() to minimize wakeup latency. */ __mwaitx(MWAITX_DISABLE_CSTATES, delay, MWAITX_ECX_TIMER_ENABLE);

5 years, 3 months

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[PATCH 8/8] xhci: Fix NULL pointer dereference in xhci_clear_tt_buffer_complete()

by Mathias Nyman

udev stored in ep->hcpriv might be NULL if tt buffer is cleared due to a halted control endpoint during device enumeration xhci_clear_tt_buffer_complete is called by hub_tt_work() once it's scheduled, and by then usb core might have freed and allocated a new udev for the next enumeration attempt. Fixes: ef513be0a905 ("usb: xhci: Add Clear_TT_Buffer") Cc: <stable(a)vger.kernel.org> # v5.3 Reported-by: Johan Hovold <johan(a)kernel.org> Signed-off-by: Mathias Nyman <mathias.nyman(a)linux.intel.com> --- drivers/usb/host/xhci.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index 00f3804f7aa7..517ec3206f6e 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -5238,8 +5238,16 @@ static void xhci_clear_tt_buffer_complete(struct usb_hcd *hcd, unsigned int ep_index; unsigned long flags; + /* + * udev might be NULL if tt buffer is cleared during a failed device + * enumeration due to a halted control endpoint. Usb core might + * have allocated a new udev for the next enumeration attempt. + */ + xhci = hcd_to_xhci(hcd); udev = (struct usb_device *)ep->hcpriv; + if (!udev) + return; slot_id = udev->slot_id; ep_index = xhci_get_endpoint_index(&ep->desc); -- 2.7.4

5 years, 3 months

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FAILED: patch "[PATCH] tick: broadcast-hrtimer: Fix a race in bc_set_next" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From b9023b91dd020ad7e093baa5122b6968c48cc9e0 Mon Sep 17 00:00:00 2001 From: Balasubramani Vivekanandan <balasubramani_vivekanandan(a)mentor.com> Date: Thu, 26 Sep 2019 15:51:01 +0200 Subject: [PATCH] tick: broadcast-hrtimer: Fix a race in bc_set_next When a cpu requests broadcasting, before starting the tick broadcast hrtimer, bc_set_next() checks if the timer callback (bc_handler) is active using hrtimer_try_to_cancel(). But hrtimer_try_to_cancel() does not provide the required synchronization when the callback is active on other core. The callback could have already executed tick_handle_oneshot_broadcast() and could have also returned. But still there is a small time window where the hrtimer_try_to_cancel() returns -1. In that case bc_set_next() returns without doing anything, but the next_event of the tick broadcast clock device is already set to a timeout value. In the race condition diagram below, CPU #1 is running the timer callback and CPU #2 is entering idle state and so calls bc_set_next(). In the worst case, the next_event will contain an expiry time, but the hrtimer will not be started which happens when the racing callback returns HRTIMER_NORESTART. The hrtimer might never recover if all further requests from the CPUs to subscribe to tick broadcast have timeout greater than the next_event of tick broadcast clock device. This leads to cascading of failures and finally noticed as rcu stall warnings Here is a depiction of the race condition CPU #1 (Running timer callback) CPU #2 (Enter idle and subscribe to tick broadcast) --------------------- --------------------- __run_hrtimer() tick_broadcast_enter() bc_handler() __tick_broadcast_oneshot_control() tick_handle_oneshot_broadcast() raw_spin_lock(&tick_broadcast_lock); dev->next_event = KTIME_MAX; //wait for tick_broadcast_lock //next_event for tick broadcast clock set to KTIME_MAX since no other cores subscribed to tick broadcasting raw_spin_unlock(&tick_broadcast_lock); if (dev->next_event == KTIME_MAX) return HRTIMER_NORESTART // callback function exits without restarting the hrtimer //tick_broadcast_lock acquired raw_spin_lock(&tick_broadcast_lock); tick_broadcast_set_event() clockevents_program_event() dev->next_event = expires; bc_set_next() hrtimer_try_to_cancel() //returns -1 since the timer callback is active. Exits without restarting the timer cpu_base->running = NULL; The comment that hrtimer cannot be armed from within the callback is wrong. It is fine to start the hrtimer from within the callback. Also it is safe to start the hrtimer from the enter/exit idle code while the broadcast handler is active. The enter/exit idle code and the broadcast handler are synchronized using tick_broadcast_lock. So there is no need for the existing try to cancel logic. All this can be removed which will eliminate the race condition as well. Fixes: 5d1638acb9f6 ("tick: Introduce hrtimer based broadcast") Originally-by: Thomas Gleixner <tglx(a)linutronix.de> Signed-off-by: Balasubramani Vivekanandan <balasubramani_vivekanandan(a)mentor.com> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Cc: stable(a)vger.kernel.org Link: https://lkml.kernel.org/r/20190926135101.12102-2-balasubramani_vivekanandan… diff --git a/kernel/time/tick-broadcast-hrtimer.c b/kernel/time/tick-broadcast-hrtimer.c index c1f5bb590b5e..b5a65e212df2 100644 --- a/kernel/time/tick-broadcast-hrtimer.c +++ b/kernel/time/tick-broadcast-hrtimer.c @@ -42,39 +42,39 @@ static int bc_shutdown(struct clock_event_device *evt) */ static int bc_set_next(ktime_t expires, struct clock_event_device *bc) { - int bc_moved; /* - * We try to cancel the timer first. If the callback is on - * flight on some other cpu then we let it handle it. If we - * were able to cancel the timer nothing can rearm it as we - * own broadcast_lock. + * This is called either from enter/exit idle code or from the + * broadcast handler. In all cases tick_broadcast_lock is held. * - * However we can also be called from the event handler of - * ce_broadcast_hrtimer itself when it expires. We cannot - * restart the timer because we are in the callback, but we - * can set the expiry time and let the callback return - * HRTIMER_RESTART. + * hrtimer_cancel() cannot be called here neither from the + * broadcast handler nor from the enter/exit idle code. The idle + * code can run into the problem described in bc_shutdown() and the + * broadcast handler cannot wait for itself to complete for obvious + * reasons. * - * Since we are in the idle loop at this point and because - * hrtimer_{start/cancel} functions call into tracing, - * calls to these functions must be bound within RCU_NONIDLE. + * Each caller tries to arm the hrtimer on its own CPU, but if the + * hrtimer callbback function is currently running, then + * hrtimer_start() cannot move it and the timer stays on the CPU on + * which it is assigned at the moment. + * + * As this can be called from idle code, the hrtimer_start() + * invocation has to be wrapped with RCU_NONIDLE() as + * hrtimer_start() can call into tracing. */ - RCU_NONIDLE( - { - bc_moved = hrtimer_try_to_cancel(&bctimer) >= 0; - if (bc_moved) { - hrtimer_start(&bctimer, expires, - HRTIMER_MODE_ABS_PINNED_HARD); - } - } - ); - - if (bc_moved) { - /* Bind the "device" to the cpu */ - bc->bound_on = smp_processor_id(); - } else if (bc->bound_on == smp_processor_id()) { - hrtimer_set_expires(&bctimer, expires); - } + RCU_NONIDLE( { + hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED_HARD); + /* + * The core tick broadcast mode expects bc->bound_on to be set + * correctly to prevent a CPU which has the broadcast hrtimer + * armed from going deep idle. + * + * As tick_broadcast_lock is held, nothing can change the cpu + * base which was just established in hrtimer_start() above. So + * the below access is safe even without holding the hrtimer + * base lock. + */ + bc->bound_on = bctimer.base->cpu_base->cpu; + } ); return 0; } @@ -100,10 +100,6 @@ static enum hrtimer_restart bc_handler(struct hrtimer *t) { ce_broadcast_hrtimer.event_handler(&ce_broadcast_hrtimer); - if (clockevent_state_oneshot(&ce_broadcast_hrtimer)) - if (ce_broadcast_hrtimer.next_event != KTIME_MAX) - return HRTIMER_RESTART; - return HRTIMER_NORESTART; }

5 years, 3 months

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FAILED: patch "[PATCH] tick: broadcast-hrtimer: Fix a race in bc_set_next" failed to apply to 4.19-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From b9023b91dd020ad7e093baa5122b6968c48cc9e0 Mon Sep 17 00:00:00 2001 From: Balasubramani Vivekanandan <balasubramani_vivekanandan(a)mentor.com> Date: Thu, 26 Sep 2019 15:51:01 +0200 Subject: [PATCH] tick: broadcast-hrtimer: Fix a race in bc_set_next When a cpu requests broadcasting, before starting the tick broadcast hrtimer, bc_set_next() checks if the timer callback (bc_handler) is active using hrtimer_try_to_cancel(). But hrtimer_try_to_cancel() does not provide the required synchronization when the callback is active on other core. The callback could have already executed tick_handle_oneshot_broadcast() and could have also returned. But still there is a small time window where the hrtimer_try_to_cancel() returns -1. In that case bc_set_next() returns without doing anything, but the next_event of the tick broadcast clock device is already set to a timeout value. In the race condition diagram below, CPU #1 is running the timer callback and CPU #2 is entering idle state and so calls bc_set_next(). In the worst case, the next_event will contain an expiry time, but the hrtimer will not be started which happens when the racing callback returns HRTIMER_NORESTART. The hrtimer might never recover if all further requests from the CPUs to subscribe to tick broadcast have timeout greater than the next_event of tick broadcast clock device. This leads to cascading of failures and finally noticed as rcu stall warnings Here is a depiction of the race condition CPU #1 (Running timer callback) CPU #2 (Enter idle and subscribe to tick broadcast) --------------------- --------------------- __run_hrtimer() tick_broadcast_enter() bc_handler() __tick_broadcast_oneshot_control() tick_handle_oneshot_broadcast() raw_spin_lock(&tick_broadcast_lock); dev->next_event = KTIME_MAX; //wait for tick_broadcast_lock //next_event for tick broadcast clock set to KTIME_MAX since no other cores subscribed to tick broadcasting raw_spin_unlock(&tick_broadcast_lock); if (dev->next_event == KTIME_MAX) return HRTIMER_NORESTART // callback function exits without restarting the hrtimer //tick_broadcast_lock acquired raw_spin_lock(&tick_broadcast_lock); tick_broadcast_set_event() clockevents_program_event() dev->next_event = expires; bc_set_next() hrtimer_try_to_cancel() //returns -1 since the timer callback is active. Exits without restarting the timer cpu_base->running = NULL; The comment that hrtimer cannot be armed from within the callback is wrong. It is fine to start the hrtimer from within the callback. Also it is safe to start the hrtimer from the enter/exit idle code while the broadcast handler is active. The enter/exit idle code and the broadcast handler are synchronized using tick_broadcast_lock. So there is no need for the existing try to cancel logic. All this can be removed which will eliminate the race condition as well. Fixes: 5d1638acb9f6 ("tick: Introduce hrtimer based broadcast") Originally-by: Thomas Gleixner <tglx(a)linutronix.de> Signed-off-by: Balasubramani Vivekanandan <balasubramani_vivekanandan(a)mentor.com> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Cc: stable(a)vger.kernel.org Link: https://lkml.kernel.org/r/20190926135101.12102-2-balasubramani_vivekanandan… diff --git a/kernel/time/tick-broadcast-hrtimer.c b/kernel/time/tick-broadcast-hrtimer.c index c1f5bb590b5e..b5a65e212df2 100644 --- a/kernel/time/tick-broadcast-hrtimer.c +++ b/kernel/time/tick-broadcast-hrtimer.c @@ -42,39 +42,39 @@ static int bc_shutdown(struct clock_event_device *evt) */ static int bc_set_next(ktime_t expires, struct clock_event_device *bc) { - int bc_moved; /* - * We try to cancel the timer first. If the callback is on - * flight on some other cpu then we let it handle it. If we - * were able to cancel the timer nothing can rearm it as we - * own broadcast_lock. + * This is called either from enter/exit idle code or from the + * broadcast handler. In all cases tick_broadcast_lock is held. * - * However we can also be called from the event handler of - * ce_broadcast_hrtimer itself when it expires. We cannot - * restart the timer because we are in the callback, but we - * can set the expiry time and let the callback return - * HRTIMER_RESTART. + * hrtimer_cancel() cannot be called here neither from the + * broadcast handler nor from the enter/exit idle code. The idle + * code can run into the problem described in bc_shutdown() and the + * broadcast handler cannot wait for itself to complete for obvious + * reasons. * - * Since we are in the idle loop at this point and because - * hrtimer_{start/cancel} functions call into tracing, - * calls to these functions must be bound within RCU_NONIDLE. + * Each caller tries to arm the hrtimer on its own CPU, but if the + * hrtimer callbback function is currently running, then + * hrtimer_start() cannot move it and the timer stays on the CPU on + * which it is assigned at the moment. + * + * As this can be called from idle code, the hrtimer_start() + * invocation has to be wrapped with RCU_NONIDLE() as + * hrtimer_start() can call into tracing. */ - RCU_NONIDLE( - { - bc_moved = hrtimer_try_to_cancel(&bctimer) >= 0; - if (bc_moved) { - hrtimer_start(&bctimer, expires, - HRTIMER_MODE_ABS_PINNED_HARD); - } - } - ); - - if (bc_moved) { - /* Bind the "device" to the cpu */ - bc->bound_on = smp_processor_id(); - } else if (bc->bound_on == smp_processor_id()) { - hrtimer_set_expires(&bctimer, expires); - } + RCU_NONIDLE( { + hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED_HARD); + /* + * The core tick broadcast mode expects bc->bound_on to be set + * correctly to prevent a CPU which has the broadcast hrtimer + * armed from going deep idle. + * + * As tick_broadcast_lock is held, nothing can change the cpu + * base which was just established in hrtimer_start() above. So + * the below access is safe even without holding the hrtimer + * base lock. + */ + bc->bound_on = bctimer.base->cpu_base->cpu; + } ); return 0; } @@ -100,10 +100,6 @@ static enum hrtimer_restart bc_handler(struct hrtimer *t) { ce_broadcast_hrtimer.event_handler(&ce_broadcast_hrtimer); - if (clockevent_state_oneshot(&ce_broadcast_hrtimer)) - if (ce_broadcast_hrtimer.next_event != KTIME_MAX) - return HRTIMER_RESTART; - return HRTIMER_NORESTART; }

5 years, 3 months

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FAILED: patch "[PATCH] tick: broadcast-hrtimer: Fix a race in bc_set_next" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From b9023b91dd020ad7e093baa5122b6968c48cc9e0 Mon Sep 17 00:00:00 2001 From: Balasubramani Vivekanandan <balasubramani_vivekanandan(a)mentor.com> Date: Thu, 26 Sep 2019 15:51:01 +0200 Subject: [PATCH] tick: broadcast-hrtimer: Fix a race in bc_set_next When a cpu requests broadcasting, before starting the tick broadcast hrtimer, bc_set_next() checks if the timer callback (bc_handler) is active using hrtimer_try_to_cancel(). But hrtimer_try_to_cancel() does not provide the required synchronization when the callback is active on other core. The callback could have already executed tick_handle_oneshot_broadcast() and could have also returned. But still there is a small time window where the hrtimer_try_to_cancel() returns -1. In that case bc_set_next() returns without doing anything, but the next_event of the tick broadcast clock device is already set to a timeout value. In the race condition diagram below, CPU #1 is running the timer callback and CPU #2 is entering idle state and so calls bc_set_next(). In the worst case, the next_event will contain an expiry time, but the hrtimer will not be started which happens when the racing callback returns HRTIMER_NORESTART. The hrtimer might never recover if all further requests from the CPUs to subscribe to tick broadcast have timeout greater than the next_event of tick broadcast clock device. This leads to cascading of failures and finally noticed as rcu stall warnings Here is a depiction of the race condition CPU #1 (Running timer callback) CPU #2 (Enter idle and subscribe to tick broadcast) --------------------- --------------------- __run_hrtimer() tick_broadcast_enter() bc_handler() __tick_broadcast_oneshot_control() tick_handle_oneshot_broadcast() raw_spin_lock(&tick_broadcast_lock); dev->next_event = KTIME_MAX; //wait for tick_broadcast_lock //next_event for tick broadcast clock set to KTIME_MAX since no other cores subscribed to tick broadcasting raw_spin_unlock(&tick_broadcast_lock); if (dev->next_event == KTIME_MAX) return HRTIMER_NORESTART // callback function exits without restarting the hrtimer //tick_broadcast_lock acquired raw_spin_lock(&tick_broadcast_lock); tick_broadcast_set_event() clockevents_program_event() dev->next_event = expires; bc_set_next() hrtimer_try_to_cancel() //returns -1 since the timer callback is active. Exits without restarting the timer cpu_base->running = NULL; The comment that hrtimer cannot be armed from within the callback is wrong. It is fine to start the hrtimer from within the callback. Also it is safe to start the hrtimer from the enter/exit idle code while the broadcast handler is active. The enter/exit idle code and the broadcast handler are synchronized using tick_broadcast_lock. So there is no need for the existing try to cancel logic. All this can be removed which will eliminate the race condition as well. Fixes: 5d1638acb9f6 ("tick: Introduce hrtimer based broadcast") Originally-by: Thomas Gleixner <tglx(a)linutronix.de> Signed-off-by: Balasubramani Vivekanandan <balasubramani_vivekanandan(a)mentor.com> Signed-off-by: Thomas Gleixner <tglx(a)linutronix.de> Cc: stable(a)vger.kernel.org Link: https://lkml.kernel.org/r/20190926135101.12102-2-balasubramani_vivekanandan… diff --git a/kernel/time/tick-broadcast-hrtimer.c b/kernel/time/tick-broadcast-hrtimer.c index c1f5bb590b5e..b5a65e212df2 100644 --- a/kernel/time/tick-broadcast-hrtimer.c +++ b/kernel/time/tick-broadcast-hrtimer.c @@ -42,39 +42,39 @@ static int bc_shutdown(struct clock_event_device *evt) */ static int bc_set_next(ktime_t expires, struct clock_event_device *bc) { - int bc_moved; /* - * We try to cancel the timer first. If the callback is on - * flight on some other cpu then we let it handle it. If we - * were able to cancel the timer nothing can rearm it as we - * own broadcast_lock. + * This is called either from enter/exit idle code or from the + * broadcast handler. In all cases tick_broadcast_lock is held. * - * However we can also be called from the event handler of - * ce_broadcast_hrtimer itself when it expires. We cannot - * restart the timer because we are in the callback, but we - * can set the expiry time and let the callback return - * HRTIMER_RESTART. + * hrtimer_cancel() cannot be called here neither from the + * broadcast handler nor from the enter/exit idle code. The idle + * code can run into the problem described in bc_shutdown() and the + * broadcast handler cannot wait for itself to complete for obvious + * reasons. * - * Since we are in the idle loop at this point and because - * hrtimer_{start/cancel} functions call into tracing, - * calls to these functions must be bound within RCU_NONIDLE. + * Each caller tries to arm the hrtimer on its own CPU, but if the + * hrtimer callbback function is currently running, then + * hrtimer_start() cannot move it and the timer stays on the CPU on + * which it is assigned at the moment. + * + * As this can be called from idle code, the hrtimer_start() + * invocation has to be wrapped with RCU_NONIDLE() as + * hrtimer_start() can call into tracing. */ - RCU_NONIDLE( - { - bc_moved = hrtimer_try_to_cancel(&bctimer) >= 0; - if (bc_moved) { - hrtimer_start(&bctimer, expires, - HRTIMER_MODE_ABS_PINNED_HARD); - } - } - ); - - if (bc_moved) { - /* Bind the "device" to the cpu */ - bc->bound_on = smp_processor_id(); - } else if (bc->bound_on == smp_processor_id()) { - hrtimer_set_expires(&bctimer, expires); - } + RCU_NONIDLE( { + hrtimer_start(&bctimer, expires, HRTIMER_MODE_ABS_PINNED_HARD); + /* + * The core tick broadcast mode expects bc->bound_on to be set + * correctly to prevent a CPU which has the broadcast hrtimer + * armed from going deep idle. + * + * As tick_broadcast_lock is held, nothing can change the cpu + * base which was just established in hrtimer_start() above. So + * the below access is safe even without holding the hrtimer + * base lock. + */ + bc->bound_on = bctimer.base->cpu_base->cpu; + } ); return 0; } @@ -100,10 +100,6 @@ static enum hrtimer_restart bc_handler(struct hrtimer *t) { ce_broadcast_hrtimer.event_handler(&ce_broadcast_hrtimer); - if (clockevent_state_oneshot(&ce_broadcast_hrtimer)) - if (ce_broadcast_hrtimer.next_event != KTIME_MAX) - return HRTIMER_RESTART; - return HRTIMER_NORESTART; }

5 years, 3 months

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FAILED: patch "[PATCH] crypto: skcipher - Unmap pages after an external error" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 0ba3c026e685573bd3534c17e27da7c505ac99c4 Mon Sep 17 00:00:00 2001 From: Herbert Xu <herbert(a)gondor.apana.org.au> Date: Fri, 6 Sep 2019 13:13:06 +1000 Subject: [PATCH] crypto: skcipher - Unmap pages after an external error skcipher_walk_done may be called with an error by internal or external callers. For those internal callers we shouldn't unmap pages but for external callers we must unmap any pages that are in use. This patch distinguishes between the two cases by checking whether walk->nbytes is zero or not. For internal callers, we now set walk->nbytes to zero prior to the call. For external callers, walk->nbytes has always been non-zero (as zero is used to indicate the termination of a walk). Reported-by: Ard Biesheuvel <ard.biesheuvel(a)linaro.org> Fixes: 5cde0af2a982 ("[CRYPTO] cipher: Added block cipher type") Cc: <stable(a)vger.kernel.org> Signed-off-by: Herbert Xu <herbert(a)gondor.apana.org.au> Tested-by: Ard Biesheuvel <ard.biesheuvel(a)linaro.org> Signed-off-by: Herbert Xu <herbert(a)gondor.apana.org.au> diff --git a/crypto/skcipher.c b/crypto/skcipher.c index 5d836fc3df3e..22753c1c7202 100644 --- a/crypto/skcipher.c +++ b/crypto/skcipher.c @@ -90,7 +90,7 @@ static inline u8 *skcipher_get_spot(u8 *start, unsigned int len) return max(start, end_page); } -static void skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize) +static int skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize) { u8 *addr; @@ -98,19 +98,21 @@ static void skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize) addr = skcipher_get_spot(addr, bsize); scatterwalk_copychunks(addr, &walk->out, bsize, (walk->flags & SKCIPHER_WALK_PHYS) ? 2 : 1); + return 0; } int skcipher_walk_done(struct skcipher_walk *walk, int err) { - unsigned int n; /* bytes processed */ - bool more; + unsigned int n = walk->nbytes; + unsigned int nbytes = 0; - if (unlikely(err < 0)) + if (!n) goto finish; - n = walk->nbytes - err; - walk->total -= n; - more = (walk->total != 0); + if (likely(err >= 0)) { + n -= err; + nbytes = walk->total - n; + } if (likely(!(walk->flags & (SKCIPHER_WALK_PHYS | SKCIPHER_WALK_SLOW | @@ -126,7 +128,7 @@ int skcipher_walk_done(struct skcipher_walk *walk, int err) memcpy(walk->dst.virt.addr, walk->page, n); skcipher_unmap_dst(walk); } else if (unlikely(walk->flags & SKCIPHER_WALK_SLOW)) { - if (err) { + if (err > 0) { /* * Didn't process all bytes. Either the algorithm is * broken, or this was the last step and it turned out @@ -134,27 +136,29 @@ int skcipher_walk_done(struct skcipher_walk *walk, int err) * the algorithm requires it. */ err = -EINVAL; - goto finish; - } - skcipher_done_slow(walk, n); - goto already_advanced; + nbytes = 0; + } else + n = skcipher_done_slow(walk, n); } + if (err > 0) + err = 0; + + walk->total = nbytes; + walk->nbytes = 0; + scatterwalk_advance(&walk->in, n); scatterwalk_advance(&walk->out, n); -already_advanced: - scatterwalk_done(&walk->in, 0, more); - scatterwalk_done(&walk->out, 1, more); + scatterwalk_done(&walk->in, 0, nbytes); + scatterwalk_done(&walk->out, 1, nbytes); - if (more) { + if (nbytes) { crypto_yield(walk->flags & SKCIPHER_WALK_SLEEP ? CRYPTO_TFM_REQ_MAY_SLEEP : 0); return skcipher_walk_next(walk); } - err = 0; -finish: - walk->nbytes = 0; +finish: /* Short-circuit for the common/fast path. */ if (!((unsigned long)walk->buffer | (unsigned long)walk->page)) goto out;

5 years, 3 months

1
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FAILED: patch "[PATCH] crypto: skcipher - Unmap pages after an external error" failed to apply to 4.4-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 0ba3c026e685573bd3534c17e27da7c505ac99c4 Mon Sep 17 00:00:00 2001 From: Herbert Xu <herbert(a)gondor.apana.org.au> Date: Fri, 6 Sep 2019 13:13:06 +1000 Subject: [PATCH] crypto: skcipher - Unmap pages after an external error skcipher_walk_done may be called with an error by internal or external callers. For those internal callers we shouldn't unmap pages but for external callers we must unmap any pages that are in use. This patch distinguishes between the two cases by checking whether walk->nbytes is zero or not. For internal callers, we now set walk->nbytes to zero prior to the call. For external callers, walk->nbytes has always been non-zero (as zero is used to indicate the termination of a walk). Reported-by: Ard Biesheuvel <ard.biesheuvel(a)linaro.org> Fixes: 5cde0af2a982 ("[CRYPTO] cipher: Added block cipher type") Cc: <stable(a)vger.kernel.org> Signed-off-by: Herbert Xu <herbert(a)gondor.apana.org.au> Tested-by: Ard Biesheuvel <ard.biesheuvel(a)linaro.org> Signed-off-by: Herbert Xu <herbert(a)gondor.apana.org.au> diff --git a/crypto/skcipher.c b/crypto/skcipher.c index 5d836fc3df3e..22753c1c7202 100644 --- a/crypto/skcipher.c +++ b/crypto/skcipher.c @@ -90,7 +90,7 @@ static inline u8 *skcipher_get_spot(u8 *start, unsigned int len) return max(start, end_page); } -static void skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize) +static int skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize) { u8 *addr; @@ -98,19 +98,21 @@ static void skcipher_done_slow(struct skcipher_walk *walk, unsigned int bsize) addr = skcipher_get_spot(addr, bsize); scatterwalk_copychunks(addr, &walk->out, bsize, (walk->flags & SKCIPHER_WALK_PHYS) ? 2 : 1); + return 0; } int skcipher_walk_done(struct skcipher_walk *walk, int err) { - unsigned int n; /* bytes processed */ - bool more; + unsigned int n = walk->nbytes; + unsigned int nbytes = 0; - if (unlikely(err < 0)) + if (!n) goto finish; - n = walk->nbytes - err; - walk->total -= n; - more = (walk->total != 0); + if (likely(err >= 0)) { + n -= err; + nbytes = walk->total - n; + } if (likely(!(walk->flags & (SKCIPHER_WALK_PHYS | SKCIPHER_WALK_SLOW | @@ -126,7 +128,7 @@ int skcipher_walk_done(struct skcipher_walk *walk, int err) memcpy(walk->dst.virt.addr, walk->page, n); skcipher_unmap_dst(walk); } else if (unlikely(walk->flags & SKCIPHER_WALK_SLOW)) { - if (err) { + if (err > 0) { /* * Didn't process all bytes. Either the algorithm is * broken, or this was the last step and it turned out @@ -134,27 +136,29 @@ int skcipher_walk_done(struct skcipher_walk *walk, int err) * the algorithm requires it. */ err = -EINVAL; - goto finish; - } - skcipher_done_slow(walk, n); - goto already_advanced; + nbytes = 0; + } else + n = skcipher_done_slow(walk, n); } + if (err > 0) + err = 0; + + walk->total = nbytes; + walk->nbytes = 0; + scatterwalk_advance(&walk->in, n); scatterwalk_advance(&walk->out, n); -already_advanced: - scatterwalk_done(&walk->in, 0, more); - scatterwalk_done(&walk->out, 1, more); + scatterwalk_done(&walk->in, 0, nbytes); + scatterwalk_done(&walk->out, 1, nbytes); - if (more) { + if (nbytes) { crypto_yield(walk->flags & SKCIPHER_WALK_SLEEP ? CRYPTO_TFM_REQ_MAY_SLEEP : 0); return skcipher_walk_next(walk); } - err = 0; -finish: - walk->nbytes = 0; +finish: /* Short-circuit for the common/fast path. */ if (!((unsigned long)walk->buffer | (unsigned long)walk->page)) goto out;

5 years, 3 months

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FAILED: patch "[PATCH] tools lib traceevent: Do not free tep->cmdlines in" failed to apply to 4.14-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From b0215e2d6a18d8331b2d4a8b38ccf3eff783edb1 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" <rostedt(a)goodmis.org> Date: Wed, 28 Aug 2019 15:05:28 -0400 Subject: [PATCH] tools lib traceevent: Do not free tep->cmdlines in add_new_comm() on failure If the re-allocation of tep->cmdlines succeeds, then the previous allocation of tep->cmdlines will be freed. If we later fail in add_new_comm(), we must not free cmdlines, and also should assign tep->cmdlines to the new allocation. Otherwise when freeing tep, the tep->cmdlines will be pointing to garbage. Fixes: a6d2a61ac653a ("tools lib traceevent: Remove some die() calls") Signed-off-by: Steven Rostedt (VMware) <rostedt(a)goodmis.org> Cc: Andrew Morton <akpm(a)linux-foundation.org> Cc: Jiri Olsa <jolsa(a)redhat.com> Cc: Namhyung Kim <namhyung(a)kernel.org> Cc: linux-trace-devel(a)vger.kernel.org Cc: stable(a)vger.kernel.org Link: http://lkml.kernel.org/r/20190828191819.970121417@goodmis.org Signed-off-by: Arnaldo Carvalho de Melo <acme(a)redhat.com> diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c index b36b536a9fcb..13fd9fdf91e0 100644 --- a/tools/lib/traceevent/event-parse.c +++ b/tools/lib/traceevent/event-parse.c @@ -269,10 +269,10 @@ static int add_new_comm(struct tep_handle *tep, errno = ENOMEM; return -1; } + tep->cmdlines = cmdlines; cmdlines[tep->cmdline_count].comm = strdup(comm); if (!cmdlines[tep->cmdline_count].comm) { - free(cmdlines); errno = ENOMEM; return -1; } @@ -283,7 +283,6 @@ static int add_new_comm(struct tep_handle *tep, tep->cmdline_count++; qsort(cmdlines, tep->cmdline_count, sizeof(*cmdlines), cmdline_cmp); - tep->cmdlines = cmdlines; return 0; }

5 years, 3 months

1
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FAILED: patch "[PATCH] tools lib traceevent: Do not free tep->cmdlines in" failed to apply to 4.9-stable tree

by gregkh＠linuxfoundation.org

The patch below does not apply to the 4.9-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable(a)vger.kernel.org>. thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From b0215e2d6a18d8331b2d4a8b38ccf3eff783edb1 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (VMware)" <rostedt(a)goodmis.org> Date: Wed, 28 Aug 2019 15:05:28 -0400 Subject: [PATCH] tools lib traceevent: Do not free tep->cmdlines in add_new_comm() on failure If the re-allocation of tep->cmdlines succeeds, then the previous allocation of tep->cmdlines will be freed. If we later fail in add_new_comm(), we must not free cmdlines, and also should assign tep->cmdlines to the new allocation. Otherwise when freeing tep, the tep->cmdlines will be pointing to garbage. Fixes: a6d2a61ac653a ("tools lib traceevent: Remove some die() calls") Signed-off-by: Steven Rostedt (VMware) <rostedt(a)goodmis.org> Cc: Andrew Morton <akpm(a)linux-foundation.org> Cc: Jiri Olsa <jolsa(a)redhat.com> Cc: Namhyung Kim <namhyung(a)kernel.org> Cc: linux-trace-devel(a)vger.kernel.org Cc: stable(a)vger.kernel.org Link: http://lkml.kernel.org/r/20190828191819.970121417@goodmis.org Signed-off-by: Arnaldo Carvalho de Melo <acme(a)redhat.com> diff --git a/tools/lib/traceevent/event-parse.c b/tools/lib/traceevent/event-parse.c index b36b536a9fcb..13fd9fdf91e0 100644 --- a/tools/lib/traceevent/event-parse.c +++ b/tools/lib/traceevent/event-parse.c @@ -269,10 +269,10 @@ static int add_new_comm(struct tep_handle *tep, errno = ENOMEM; return -1; } + tep->cmdlines = cmdlines; cmdlines[tep->cmdline_count].comm = strdup(comm); if (!cmdlines[tep->cmdline_count].comm) { - free(cmdlines); errno = ENOMEM; return -1; } @@ -283,7 +283,6 @@ static int add_new_comm(struct tep_handle *tep, tep->cmdline_count++; qsort(cmdlines, tep->cmdline_count, sizeof(*cmdlines), cmdline_cmp); - tep->cmdlines = cmdlines; return 0; }

5 years, 3 months

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