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46 lines
1.5 KiB
Diff
46 lines
1.5 KiB
Diff
From efdde709efccc4f95c7641eea8960dbc31fc58b5 Mon Sep 17 00:00:00 2001
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From: P33M <p33m@github.com>
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Date: Thu, 15 Feb 2018 11:22:44 +0000
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Subject: [PATCH 207/454] dwc_otg: add smp_mb() to prevent driver state
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corruption on boot
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Occasional crashes have been seen where the FIQ code dereferences
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invalid/random pointers immediately after being set up, leading to
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panic on boot.
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The crash occurs as the FIQ code races against hcd_init_fiq() and
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the hcd_init_fiq() code races against the outstanding memory stores
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from dwc_otg_hcd_init(). Use explicit barriers after touching
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driver state.
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---
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drivers/usb/host/dwc_otg/dwc_otg_hcd_linux.c | 11 ++++++++++-
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1 file changed, 10 insertions(+), 1 deletion(-)
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--- a/drivers/usb/host/dwc_otg/dwc_otg_hcd_linux.c
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+++ b/drivers/usb/host/dwc_otg/dwc_otg_hcd_linux.c
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@@ -519,6 +519,11 @@ static void hcd_init_fiq(void *cookie)
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DWC_ERROR("Can't get FIQ irq");
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return;
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}
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+ /*
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+ * We could take an interrupt immediately after enabling the FIQ.
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+ * Ensure coherency of hcd->fiq_state.
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+ */
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+ smp_mb();
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enable_fiq(irq);
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local_fiq_enable();
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#endif
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@@ -598,7 +603,11 @@ int hcd_init(dwc_bus_dev_t *_dev)
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if (fiq_enable) {
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if (num_online_cpus() > 1) {
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- /* bcm2709: can run the FIQ on a separate core to IRQs */
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+ /*
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+ * bcm2709: can run the FIQ on a separate core to IRQs.
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+ * Ensure driver state is visible to other cores before setting up the FIQ.
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+ */
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+ smp_mb();
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smp_call_function_single(1, hcd_init_fiq, otg_dev, 1);
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} else {
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smp_call_function_single(0, hcd_init_fiq, otg_dev, 1);
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