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    SubjectRe: [PATCH v2] drm/radeon: evergreen_hpd_init()/_fini(): fix HPD IRQ bitset
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    On Mon, Mar 21, 2016 at 8:10 AM, Nicolai Stange <nicstange@gmail.com> wrote:
    > The values of all but the RADEON_HPD_NONE members of the radeon_hpd_id
    > enum transform 1:1 into bit positions within the 'enabled' bitset as
    > assembled by evergreen_hpd_init():
    >
    > enabled |= 1 << radeon_connector->hpd.hpd;
    >
    > However, if ->hpd.hpd happens to equal RADEON_HPD_NONE == 0xff, UBSAN
    > reports
    >
    > UBSAN: Undefined behaviour in drivers/gpu/drm/radeon/evergreen.c:1867:16
    > shift exponent 255 is too large for 32-bit type 'int'
    > [...]
    > Call Trace:
    > [<ffffffff818c4d35>] dump_stack+0xbc/0x117
    > [<ffffffff818c4c79>] ? _atomic_dec_and_lock+0x169/0x169
    > [<ffffffff819411bb>] ubsan_epilogue+0xd/0x4e
    > [<ffffffff81941cbc>] __ubsan_handle_shift_out_of_bounds+0x1fb/0x254
    > [<ffffffffa0ba7f2e>] ? atom_execute_table+0x3e/0x50 [radeon]
    > [<ffffffff81941ac1>] ? __ubsan_handle_load_invalid_value+0x158/0x158
    > [<ffffffffa0b87700>] ? radeon_get_pll_use_mask+0x130/0x130 [radeon]
    > [<ffffffff81219930>] ? wake_up_klogd_work_func+0x60/0x60
    > [<ffffffff8121a35e>] ? vprintk_default+0x3e/0x60
    > [<ffffffffa0c603c4>] evergreen_hpd_init+0x274/0x2d0 [radeon]
    > [<ffffffffa0c603c4>] ? evergreen_hpd_init+0x274/0x2d0 [radeon]
    > [<ffffffffa0bd196e>] radeon_modeset_init+0x8ce/0x18d0 [radeon]
    > [<ffffffffa0b71d86>] radeon_driver_load_kms+0x186/0x350 [radeon]
    > [<ffffffffa03b6b16>] drm_dev_register+0xc6/0x100 [drm]
    > [<ffffffffa03bc8c4>] drm_get_pci_dev+0xe4/0x490 [drm]
    > [<ffffffff814b83f0>] ? kfree+0x220/0x370
    > [<ffffffffa0b687c2>] radeon_pci_probe+0x112/0x140 [radeon]
    > [...]
    > =====================================================================
    > radeon 0000:01:00.0: No connectors reported connected with modes
    >
    > At least on x86, there should be no user-visible impact as there
    >
    > 1 << 0xff == 1 << (0xff & 31) == 1 << 31
    >
    > holds and 31 > RADEON_MAX_HPD_PINS. Thus, this patch is a cosmetic one.
    >
    > All of the above applies analogously to evergreen_hpd_fini().
    >
    > Silence UBSAN by checking ->hpd.hpd for RADEON_HPD_NONE before oring it
    > into the 'enabled' bitset in evergreen_hpd_init() or the 'disabled' bitset
    > in evergreen_hpd_fini() respectively.
    >
    > Signed-off-by: Nicolai Stange <nicstange@gmail.com>

    Can you please fix all instances of this? This same pattern is
    repeated in various asic families.

    Alex


    > ---
    > Applicable to linux-next-20160321.
    >
    > Changes to v1:
    > - Turn commit message's impact part into a non-impact part.
    >
    > drivers/gpu/drm/radeon/evergreen.c | 6 ++++--
    > 1 file changed, 4 insertions(+), 2 deletions(-)
    >
    > diff --git a/drivers/gpu/drm/radeon/evergreen.c b/drivers/gpu/drm/radeon/evergreen.c
    > index 76c4bdf..6360717 100644
    > --- a/drivers/gpu/drm/radeon/evergreen.c
    > +++ b/drivers/gpu/drm/radeon/evergreen.c
    > @@ -1864,7 +1864,8 @@ void evergreen_hpd_init(struct radeon_device *rdev)
    > break;
    > }
    > radeon_hpd_set_polarity(rdev, radeon_connector->hpd.hpd);
    > - enabled |= 1 << radeon_connector->hpd.hpd;
    > + if (radeon_connector->hpd.hpd != RADEON_HPD_NONE)
    > + enabled |= 1 << radeon_connector->hpd.hpd;
    > }
    > radeon_irq_kms_enable_hpd(rdev, enabled);
    > }
    > @@ -1907,7 +1908,8 @@ void evergreen_hpd_fini(struct radeon_device *rdev)
    > default:
    > break;
    > }
    > - disabled |= 1 << radeon_connector->hpd.hpd;
    > + if (radeon_connector->hpd.hpd != RADEON_HPD_NONE)
    > + disabled |= 1 << radeon_connector->hpd.hpd;
    > }
    > radeon_irq_kms_disable_hpd(rdev, disabled);
    > }
    > --
    > 2.7.3
    >
    > _______________________________________________
    > dri-devel mailing list
    > dri-devel@lists.freedesktop.org
    > https://lists.freedesktop.org/mailman/listinfo/dri-devel

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