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Miller" , Maxime Coquelin , Alexandre Torgue CC: Nicolas Toromanoff , , , , Subject: [PATCH 5/5] crypto: stm32/crc: protect from concurrent accesses Date: Tue, 12 May 2020 16:11:13 +0200 Message-ID: <20200512141113.18972-6-nicolas.toromanoff@st.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200512141113.18972-1-nicolas.toromanoff@st.com> References: <20200512141113.18972-1-nicolas.toromanoff@st.com> MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.75.127.46] X-ClientProxiedBy: SFHDAG4NODE2.st.com (10.75.127.11) To SFHDAG6NODE1.st.com (10.75.127.16) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.676 definitions=2020-05-12_04:2020-05-11,2020-05-12 signatures=0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Protect STM32 CRC device from concurrent accesses. As we create a spinlocked section that increase with buffer size, we provide a module parameter to release the pressure by splitting critical section in chunks. Size of each chunk is defined in burst_size module parameter. By default burst_size=0, i.e. don't split incoming buffer. Signed-off-by: Nicolas Toromanoff --- drivers/crypto/stm32/stm32-crc32.c | 47 ++++++++++++++++++++++++++++-- 1 file changed, 45 insertions(+), 2 deletions(-) diff --git a/drivers/crypto/stm32/stm32-crc32.c b/drivers/crypto/stm32/stm32-crc32.c index 413415c216ef..3ba41148c2a4 100644 --- a/drivers/crypto/stm32/stm32-crc32.c +++ b/drivers/crypto/stm32/stm32-crc32.c @@ -35,11 +35,16 @@ #define CRC_AUTOSUSPEND_DELAY 50 +static unsigned int burst_size; +module_param(burst_size, uint, 0644); +MODULE_PARM_DESC(burst_size, "Select burst byte size (0 unlimited)"); + struct stm32_crc { struct list_head list; struct device *dev; void __iomem *regs; struct clk *clk; + spinlock_t lock; }; struct stm32_crc_list { @@ -109,6 +114,7 @@ static int stm32_crc_init(struct shash_desc *desc) struct stm32_crc_desc_ctx *ctx = shash_desc_ctx(desc); struct stm32_crc_ctx *mctx = crypto_shash_ctx(desc->tfm); struct stm32_crc *crc; + unsigned long flags; crc = stm32_crc_get_next_crc(); if (!crc) @@ -116,6 +122,8 @@ static int stm32_crc_init(struct shash_desc *desc) pm_runtime_get_sync(crc->dev); + spin_lock_irqsave(&crc->lock, flags); + /* Reset, set key, poly and configure in bit reverse mode */ writel_relaxed(bitrev32(mctx->key), crc->regs + CRC_INIT); writel_relaxed(bitrev32(mctx->poly), crc->regs + CRC_POL); @@ -125,18 +133,21 @@ static int stm32_crc_init(struct shash_desc *desc) /* Store partial result */ ctx->partial = readl_relaxed(crc->regs + CRC_DR); + spin_unlock_irqrestore(&crc->lock, flags); + pm_runtime_mark_last_busy(crc->dev); pm_runtime_put_autosuspend(crc->dev); return 0; } -static int stm32_crc_update(struct shash_desc *desc, const u8 *d8, - unsigned int length) +static int burst_update(struct shash_desc *desc, const u8 *d8, + size_t length) { struct stm32_crc_desc_ctx *ctx = shash_desc_ctx(desc); struct stm32_crc_ctx *mctx = crypto_shash_ctx(desc->tfm); struct stm32_crc *crc; + unsigned long flags; crc = stm32_crc_get_next_crc(); if (!crc) @@ -144,6 +155,8 @@ static int stm32_crc_update(struct shash_desc *desc, const u8 *d8, pm_runtime_get_sync(crc->dev); + spin_lock_irqsave(&crc->lock, flags); + /* * Restore previously calculated CRC for this context as init value * Restore polynomial configuration @@ -182,12 +195,40 @@ static int stm32_crc_update(struct shash_desc *desc, const u8 *d8, /* Store partial result */ ctx->partial = readl_relaxed(crc->regs + CRC_DR); + spin_unlock_irqrestore(&crc->lock, flags); + pm_runtime_mark_last_busy(crc->dev); pm_runtime_put_autosuspend(crc->dev); return 0; } +static int stm32_crc_update(struct shash_desc *desc, const u8 *d8, + unsigned int length) +{ + const unsigned int burst_sz = burst_size; + unsigned int rem_sz; + const u8 *cur; + size_t size; + int ret; + + if (!burst_sz) + return burst_update(desc, d8, length); + + /* Digest first bytes not 32bit aligned at first pass in the loop */ + size = min(length, + burst_sz + (unsigned int)d8 - ALIGN_DOWN((unsigned int)d8, + sizeof(u32))); + for (rem_sz = length, cur = d8; rem_sz; + rem_sz -= size, cur += size, size = min(rem_sz, burst_sz)) { + ret = burst_update(desc, cur, size); + if (ret) + return ret; + } + + return 0; +} + static int stm32_crc_final(struct shash_desc *desc, u8 *out) { struct stm32_crc_desc_ctx *ctx = shash_desc_ctx(desc); @@ -300,6 +341,8 @@ static int stm32_crc_probe(struct platform_device *pdev) pm_runtime_irq_safe(dev); pm_runtime_enable(dev); + spin_lock_init(&crc->lock); + platform_set_drvdata(pdev, crc); spin_lock(&crc_list.lock); -- 2.17.1