From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paulo Zanoni Subject: Re: [PATCH] drm/i915/dp: fix shifting by a negative number of bits Date: Wed, 12 Sep 2018 15:02:30 -0700 Message-ID: <1536789750.2958.17.camel@intel.com> References: <20180912143153.GA27564@embeddedor.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <20180912143153.GA27564@embeddedor.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: "Gustavo A. R. Silva" , Jani Nikula , Joonas Lahtinen , David Airlie Cc: intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, "Vivi, Rodrigo" List-Id: dri-devel@lists.freedesktop.org RW0gUXVhLCAyMDE4LTA5LTEyIMOgcyAwOTozMSAtMDUwMCwgR3VzdGF2byBBLiBSLiBTaWx2YSBl c2NyZXZldToKPiBGdW5jdGlvbiBpbnRlbF9wb3J0X3RvX3RjKCkgcmV0dXJucyBQT1JUX1RDX05P TkUgb24gZXJyb3IsIHdoaWNoIGlzCj4gYSBuZWdhdGl2ZSB2YWx1ZSAtMS4gSW4gY2FzZSBQT1JU X1RDX05PTkUgaXMgcmV0dXJuZWQsIHRoZXJlIGlzIGFuCj4gdW5kZWZpbmVkIGJlaGF2aW9yIHdo ZW4gc2hpZnRpbmcgYnkgYSBuZWdhdGl2ZSBudW1iZXIgb2YgYml0cyBpbgo+IGJvdGggRFBfUEhZ X01PREVfU1RBVFVTX05PVF9TQUZFIGFuZCBQX1BIWV9NT0RFX1NUQVRVU19DT01QTEVURUQKPiBt YWNyb3MuCj4gCj4gRml4IHRoaXMgYnkgYWRkaW5nIHNhbml0eSBjaGVja3Mgb24gaW50ZWxfcG9y dF90b190YyByZXR1cm4gdmFsdWUsCj4gYmVmb3JlCj4gdXNpbmcgbWFjcm9zIERQX1BIWV9NT0RF X1NUQVRVU19OT1RfU0FGRSBhbmQKPiBQX1BIWV9NT0RFX1NUQVRVU19DT01QTEVURUQuCgpUaGlz IHdhcyBqdXN0IGRpc2N1c3NlZCB5ZXN0ZXJkYXkgaW4gYSBwYXRjaCBieSBSb2RyaWdvOgoKaHR0 cHM6Ly9wYXRjaHdvcmsuZnJlZWRlc2t0b3Aub3JnL3BhdGNoLzI0NjkwMy8KCkkgd291bGQgcGVy c29uYWxseSBwcmVmZXIgaGlzIHZlcnNpb24gYmVjYXVzZSBpdCBhdm9pZHMgcGFzc2luZyAtMSB0 bwpyZWdpc3RlciBtYWNyb3MgdGhhdCBDb3Zlcml0eSBkb2Vzbid0IHNlZW0gdG8gY2FyZSBhYm91 dCwgaXQncyBhIHNpbmdsZQpjaGVjayBhbmQgaXQgcHJpbnRzIFdBUk4oKSBpbnN0ZWFkIG9mIERS TV9ERUJVR19LTVMoKS4KCkFsdGhvdWdoIEkgZG8gcHJlZmVyIHlvdXIgY29tbWl0IG1lc3NhZ2Ug ZXhwbGFuYXRpb24gOikuCgpQZXJoYXBzIEkgc2hvdWxkIHJlY29uc2lkZXIgbXkgdm90ZSB0byBu b3QgbWVyZ2UgaXQuIE9yIHdlIGNvdWxkCmFjdHVhbGx5IGdvIGFuZCB0ZXN0IHdoYXQgaGFwcGVu cyB3aGVuIGludGVsX3BvcnRfdG9fdGMoKSBpcyBicm9rZW4sCmZpeGluZyBhbGwgdGhlIGlzc3Vl cyBpbnN0ZWFkIG9mIGp1c3QgdGhlIG9uZXMgcmVwb3J0ZWQgYnkgQ292ZXJpdHkuCgpBbnl3YXks IFJvZHJpZ28ncyBwYXRjaCB3aXRoIGFuIGltcHJvdmVkIGNvbW1pdCBtZXNzYWdlIGNvdWxkIHJl Y2VpdmUKbXkgUi1CIHRhZyBub3cuCgo+IAo+IEFkZHJlc3Nlcy1Db3Zlcml0eS1JRDogMTQ3MzMy NCAoIkJhZCBiaXQgc2hpZnQgb3BlcmF0aW9uIikKPiBBZGRyZXNzZXMtQ292ZXJpdHktSUQ6IDE0 NzMzMjUgKCJCYWQgYml0IHNoaWZ0IG9wZXJhdGlvbiIpCj4gRml4ZXM6IDM5ZDFlMjM0ZTFlMSAo ImRybS9pOTE1L2ljbDogaW1wbGVtZW50IHRoZSB0Yy9sZWdhY3kgSFBECj4ge2Rpcyx9Y29ubmVj dCBmbG93cyIpCj4gU2lnbmVkLW9mZi1ieTogR3VzdGF2byBBLiBSLiBTaWx2YSA8Z3VzdGF2b0Bl bWJlZGRlZG9yLmNvbT4KPiAtLS0KPiAgZHJpdmVycy9ncHUvZHJtL2k5MTUvaW50ZWxfZHAuYyB8 IDkgKysrKysrKysrCj4gIDEgZmlsZSBjaGFuZ2VkLCA5IGluc2VydGlvbnMoKykKPiAKPiBkaWZm IC0tZ2l0IGEvZHJpdmVycy9ncHUvZHJtL2k5MTUvaW50ZWxfZHAuYwo+IGIvZHJpdmVycy9ncHUv ZHJtL2k5MTUvaW50ZWxfZHAuYwo+IGluZGV4IDQzNmMyMmQuLmUzNGI3YjEgMTAwNjQ0Cj4gLS0t IGEvZHJpdmVycy9ncHUvZHJtL2k5MTUvaW50ZWxfZHAuYwo+ICsrKyBiL2RyaXZlcnMvZ3B1L2Ry bS9pOTE1L2ludGVsX2RwLmMKPiBAQCAtNDgxMSw2ICs0ODExLDExIEBAIHN0YXRpYyBib29sIGlj bF90Y19waHlfY29ubmVjdChzdHJ1Y3QKPiBkcm1faTkxNV9wcml2YXRlICpkZXZfcHJpdiwKPiAg CSAgICBkaWdfcG9ydC0+dGNfdHlwZSAhPSBUQ19QT1JUX1RZUEVDKQo+ICAJCXJldHVybiB0cnVl Owo+ICAKPiArCWlmICh0Y19wb3J0IDwgMCkgewo+ICsJCURSTV9ERUJVR19LTVMoIkJhZCBUQyBw b3J0ICVkXG4iLCB0Y19wb3J0KTsKPiArCQlyZXR1cm4gZmFsc2U7Cj4gKwl9Cj4gKwo+ICAJdmFs ID0gSTkxNV9SRUFEKFBPUlRfVFhfREZMRVhEUFBNUyk7Cj4gIAlpZiAoISh2YWwgJiBEUF9QSFlf TU9ERV9TVEFUVVNfQ09NUExFVEVEKHRjX3BvcnQpKSkgewo+ICAJCURSTV9ERUJVR19LTVMoIkRQ IFBIWSBmb3IgVEMgcG9ydCAlZCBub3QgcmVhZHlcbiIsCj4gdGNfcG9ydCk7Cj4gQEAgLTQ4NTcs NiArNDg2MiwxMCBAQCBzdGF0aWMgdm9pZCBpY2xfdGNfcGh5X2Rpc2Nvbm5lY3Qoc3RydWN0Cj4g ZHJtX2k5MTVfcHJpdmF0ZSAqZGV2X3ByaXYsCj4gIAkgICAgZGlnX3BvcnQtPnRjX3R5cGUgIT0g VENfUE9SVF9UWVBFQykKPiAgCQlyZXR1cm47Cj4gIAo+ICsJaWYgKHRjX3BvcnQgPCAwKSB7Cj4g KwkJRFJNX0RFQlVHX0tNUygiQmFkIFRDIHBvcnQgJWRcbiIsIHRjX3BvcnQpOwo+ICsJCXJldHVy bjsKPiArCX0KPiAgCS8qCj4gIAkgKiBUaGlzIGZ1bmN0aW9uIG1heSBiZSBjYWxsZWQgbWFueSB0 aW1lcyBpbiBhIHJvdyB3aXRob3V0Cj4gYW4gSFBEIGV2ZW50Cj4gIAkgKiBpbiBiZXR3ZWVuLCBz byB0cnkgdG8gYXZvaWQgdGhlIHdyaXRlIHdoZW4gd2UgY2FuLgpfX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fXwpkcmktZGV2ZWwgbWFpbGluZyBsaXN0CmRyaS1k ZXZlbEBsaXN0cy5mcmVlZGVza3RvcC5vcmcKaHR0cHM6Ly9saXN0cy5mcmVlZGVza3RvcC5vcmcv bWFpbG1hbi9saXN0aW5mby9kcmktZGV2ZWwK From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 52A98C070C3 for ; 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d="scan'208";a="91202185" Received: from przanoni-mobl.jf.intel.com ([10.24.10.174]) by orsmga002.jf.intel.com with ESMTP; 12 Sep 2018 15:02:31 -0700 Message-ID: <1536789750.2958.17.camel@intel.com> Subject: Re: [PATCH] drm/i915/dp: fix shifting by a negative number of bits From: Paulo Zanoni To: "Gustavo A. R. Silva" , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie Cc: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, "Vivi, Rodrigo" Date: Wed, 12 Sep 2018 15:02:30 -0700 In-Reply-To: <20180912143153.GA27564@embeddedor.com> References: <20180912143153.GA27564@embeddedor.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.26.6 (3.26.6-1.fc27) Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Qua, 2018-09-12 às 09:31 -0500, Gustavo A. R. Silva escreveu: > Function intel_port_to_tc() returns PORT_TC_NONE on error, which is > a negative value -1. In case PORT_TC_NONE is returned, there is an > undefined behavior when shifting by a negative number of bits in > both DP_PHY_MODE_STATUS_NOT_SAFE and P_PHY_MODE_STATUS_COMPLETED > macros. > > Fix this by adding sanity checks on intel_port_to_tc return value, > before > using macros DP_PHY_MODE_STATUS_NOT_SAFE and > P_PHY_MODE_STATUS_COMPLETED. This was just discussed yesterday in a patch by Rodrigo: https://patchwork.freedesktop.org/patch/246903/ I would personally prefer his version because it avoids passing -1 to register macros that Coverity doesn't seem to care about, it's a single check and it prints WARN() instead of DRM_DEBUG_KMS(). Although I do prefer your commit message explanation :). Perhaps I should reconsider my vote to not merge it. Or we could actually go and test what happens when intel_port_to_tc() is broken, fixing all the issues instead of just the ones reported by Coverity. Anyway, Rodrigo's patch with an improved commit message could receive my R-B tag now. > > Addresses-Coverity-ID: 1473324 ("Bad bit shift operation") > Addresses-Coverity-ID: 1473325 ("Bad bit shift operation") > Fixes: 39d1e234e1e1 ("drm/i915/icl: implement the tc/legacy HPD > {dis,}connect flows") > Signed-off-by: Gustavo A. R. Silva > --- > drivers/gpu/drm/i915/intel_dp.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/drivers/gpu/drm/i915/intel_dp.c > b/drivers/gpu/drm/i915/intel_dp.c > index 436c22d..e34b7b1 100644 > --- a/drivers/gpu/drm/i915/intel_dp.c > +++ b/drivers/gpu/drm/i915/intel_dp.c > @@ -4811,6 +4811,11 @@ static bool icl_tc_phy_connect(struct > drm_i915_private *dev_priv, > dig_port->tc_type != TC_PORT_TYPEC) > return true; > > + if (tc_port < 0) { > + DRM_DEBUG_KMS("Bad TC port %d\n", tc_port); > + return false; > + } > + > val = I915_READ(PORT_TX_DFLEXDPPMS); > if (!(val & DP_PHY_MODE_STATUS_COMPLETED(tc_port))) { > DRM_DEBUG_KMS("DP PHY for TC port %d not ready\n", > tc_port); > @@ -4857,6 +4862,10 @@ static void icl_tc_phy_disconnect(struct > drm_i915_private *dev_priv, > dig_port->tc_type != TC_PORT_TYPEC) > return; > > + if (tc_port < 0) { > + DRM_DEBUG_KMS("Bad TC port %d\n", tc_port); > + return; > + } > /* > * This function may be called many times in a row without > an HPD event > * in between, so try to avoid the write when we can.