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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Jon Hunter <jonathanh@nvidia.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.10 173/243] PCI: tegra194: Fix tegra_pcie_ep_raise_msi_irq() ill-defined shift
Date:   Mon, 19 Jul 2021 16:53:22 +0200
Message-Id: <20210719144946.486234050@linuxfoundation.org>
In-Reply-To: <20210719144940.904087935@linuxfoundation.org>
References: <20210719144940.904087935@linuxfoundation.org>
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From: Jon Hunter <jonathanh@nvidia.com>

[ Upstream commit f67092eff2bd40650aad54a1a1910160f41d864a ]

tegra_pcie_ep_raise_msi_irq() shifted a signed 32-bit value left by 31
bits.  The behavior of this is implementation-defined.

Replace the shift by BIT(), which is well-defined.

Found by cppcheck:

  $ cppcheck --enable=all drivers/pci/controller/dwc/pcie-tegra194.c
  Checking drivers/pci/controller/dwc/pcie-tegra194.c ...

  drivers/pci/controller/dwc/pcie-tegra194.c:1829:23: portability: Shifting signed 32-bit value by 31 bits is implementation-defined behaviour. See condition at line 1826.  [shiftTooManyBitsSigned]

  appl_writel(pcie, (1 << irq), APPL_MSI_CTRL_1);
                     ^

[bhelgaas: commit log]
Link: https://lore.kernel.org/r/20210618160219.303092-1-jonathanh@nvidia.com
Fixes: c57247f940e8 ("PCI: tegra: Add support for PCIe endpoint mode in Tegra194")
Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/pci/controller/dwc/pcie-tegra194.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index d788f4d7f9aa..506f6a294eac 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -1841,7 +1841,7 @@ static int tegra_pcie_ep_raise_msi_irq(struct tegra_pcie_dw *pcie, u16 irq)
 	if (unlikely(irq > 31))
 		return -EINVAL;
 
-	appl_writel(pcie, (1 << irq), APPL_MSI_CTRL_1);
+	appl_writel(pcie, BIT(irq), APPL_MSI_CTRL_1);
 
 	return 0;
 }
-- 
2.30.2