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Wed, 03 Jun 2026 21:50:44 -0700 (PDT) X-Received: by 2002:a05:6a00:4191:b0:842:5931:7b88 with SMTP id d2e1a72fcca58-84284dcedc6mr6339840b3a.1.1780548643554; Wed, 03 Jun 2026 21:50:43 -0700 (PDT) Received: from [10.217.222.63] ([202.46.22.19]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8428291ed20sm5397566b3a.61.2026.06.03.21.50.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 03 Jun 2026 21:50:42 -0700 (PDT) Subject: Re: [PATCH 3/4] crypto: qcom-rng - Remove crypto_rng interface To: Eric Biggers , linux-crypto@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Om Prakash Singh , Bjorn Andersson , Neil Armstrong , linux-arm-msm@vger.kernel.org, Olivia Mackall , stable@vger.kernel.org References: <20260530020332.143058-1-ebiggers@kernel.org> <20260530020332.143058-4-ebiggers@kernel.org> From: Neeraj Soni Message-ID: <021127c9-baff-816d-e053-897a7d4043d8@oss.qualcomm.com> Date: Thu, 4 Jun 2026 10:20:38 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <20260530020332.143058-4-ebiggers@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit X-Proofpoint-GUID: bf6O5hxgf22oZDMcFbDF76619-eBdl-Y X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNjA0MDA0MyBTYWx0ZWRfX3hCucWKli8HC hfPytYSAX7R1m+X9W51XmzflOYNGpzkTa6hNgplMBUQgJ6/FbARdWyEFAv8tT/xhwuEXBdz2VBh /ZfhWYPI4/FrlPHtkQb+Ewc2MZUB1BTLGnNjSVFKyADW0Cx6qED3AdSqspnJxJJeBsaOaDQ+P6M iObryizZiQ59+UW0vm1ShBKO+Bb9xKm8FW7ZBhjfMFFrjwV253KZUkRSuKw7Bb/p54BwhqnIYcT Hs40OophJyV8nFr5FnhwU2zmtHfgl0nW3rBuQ+RmGCL9klMCc01SzYZMfs0m2HlN1KE8jVYV8cw 2r2oi34D8uOQq8qLUAUtpzANHPSPPE2K7n9YaeTksi/ckLmVoGWbFHbsniRi2LGH4sXaFOgr1Z3 XM5zirYuRHZvOM+pcKikWlCrfU6WvWVDA1qg0tiqiBshxOksLT22T7tgRRKPKRpXqoUIucwi7Ex eLa9QrY2//igNPO8s3g== X-Authority-Analysis: v=2.4 cv=DbcnbPtW c=1 sm=1 tr=0 ts=6a210424 cx=c_pps a=mDZGXZTwRPZaeRUbqKGCBw==:117 a=fChuTYTh2wq5r3m49p7fHw==:17 a=IkcTkHD0fZMA:10 a=FelO9ux0wxsA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=yOCtJkima9RkubShWh1s:22 a=VwQbUJbxAAAA:8 a=cDBTOOi3T2z0a7_xwZkA:9 a=QEXdDO2ut3YA:10 a=zc0IvFSfCIW2DFIPzwfm:22 X-Proofpoint-ORIG-GUID: bf6O5hxgf22oZDMcFbDF76619-eBdl-Y X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-06-04_02,2026-05-28_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 adultscore=0 spamscore=0 phishscore=0 bulkscore=0 lowpriorityscore=0 clxscore=1015 impostorscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605210000 definitions=main-2606040043 On 5/30/2026 7:33 AM, Eric Biggers wrote: > qcom-rng.c exposes the same hardware through two completely separate > interfaces, crypto_rng and hwrng. However, the implementation of this > is buggy because it permits generation operations from these interfaces > to run concurrently with each other, accessing the same registers. That > is, qcom_rng_generate() synchronizes with itself but not with > qcom_hwrng_read(). This results in potential repetition of output from > the RNG, output of non-random values, etc. > > Fortunately, there's actually no point in hardware RNG drivers > implementing the crypto_rng interface. It's not actually used by > anything besides the "rng" algorithm type of AF_ALG, which in turn is > not actually used in practice. Other crypto_rng hardware drivers are How it was established that there are no active users/clints for qcom-rng using crypto_rng interface? If there is no concrete way to do then this patch breaks backward compatibility. > likewise being phased out, leaving just the hwrng support. > > Thus, remove it to simplify the code and avoid conflict (and confusion) > with the hwrng interface which is the one that actually matters. > > Note that while this means the driver stops supporting "qcom,prng" and > "qcom,prng-ee", it didn't do anything useful on SoCs with those anyway. > > Fixes: f29cd5bb64c2 ("crypto: qcom-rng - Add hw_random interface support") > Cc: stable@vger.kernel.org > Signed-off-by: Eric Biggers > --- > drivers/crypto/Kconfig | 1 - > drivers/crypto/qcom-rng.c | 175 ++------------------------------------ > 2 files changed, 9 insertions(+), 167 deletions(-) > > diff --git a/drivers/crypto/Kconfig b/drivers/crypto/Kconfig > index 3449b3c9c6ad..a12cd677467b 100644 > --- a/drivers/crypto/Kconfig > +++ b/drivers/crypto/Kconfig > @@ -658,11 +658,10 @@ config CRYPTO_DEV_QCE_SW_MAX_LEN > > config CRYPTO_DEV_QCOM_RNG > tristate "Qualcomm Random Number Generator Driver" > depends on ARCH_QCOM || COMPILE_TEST > depends on HW_RANDOM > - select CRYPTO_RNG > help > This driver provides support for the Random Number > Generator hardware found on Qualcomm SoCs. > > To compile this driver as a module, choose M here. The > diff --git a/drivers/crypto/qcom-rng.c b/drivers/crypto/qcom-rng.c > index b7f3b9695dac..48b605687b28 100644 > --- a/drivers/crypto/qcom-rng.c > +++ b/drivers/crypto/qcom-rng.c > @@ -1,14 +1,11 @@ > // SPDX-License-Identifier: GPL-2.0 > // Copyright (c) 2017-18 Linaro Limited > // > // Based on msm-rng.c and downstream driver > > -#include > -#include > #include > -#include > #include > #include > #include > #include > #include > @@ -30,28 +27,15 @@ > #define WORD_SZ 4 > > #define QCOM_TRNG_QUALITY 1024 > > struct qcom_rng { > - struct mutex lock; > void __iomem *base; > struct clk *clk; > struct hwrng hwrng; > - struct qcom_rng_match_data *match_data; > }; > > -struct qcom_rng_ctx { > - struct qcom_rng *rng; > -}; > - > -struct qcom_rng_match_data { > - bool skip_init; > - bool hwrng_support; > -}; > - > -static struct qcom_rng *qcom_rng_dev; > - > static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max) > { > unsigned int currsize = 0; > u32 val; > int ret; > @@ -77,41 +61,10 @@ static int qcom_rng_read(struct qcom_rng *rng, u8 *data, unsigned int max) > } while (currsize < max); > > return currsize; > } > > -static int qcom_rng_generate(struct crypto_rng *tfm, > - const u8 *src, unsigned int slen, > - u8 *dstn, unsigned int dlen) > -{ > - struct qcom_rng_ctx *ctx = crypto_rng_ctx(tfm); > - struct qcom_rng *rng = ctx->rng; > - int ret; > - > - ret = clk_prepare_enable(rng->clk); > - if (ret) > - return ret; > - > - mutex_lock(&rng->lock); > - > - ret = qcom_rng_read(rng, dstn, dlen); > - > - mutex_unlock(&rng->lock); > - clk_disable_unprepare(rng->clk); > - > - if (ret >= 0) > - ret = 0; > - > - return ret; > -} > - > -static int qcom_rng_seed(struct crypto_rng *tfm, const u8 *seed, > - unsigned int slen) > -{ > - return 0; > -} > - > static int qcom_hwrng_init(struct hwrng *hwrng) > { > struct qcom_rng *qrng = container_of(hwrng, struct qcom_rng, hwrng); > > return clk_prepare_enable(qrng->clk); > @@ -129,159 +82,49 @@ static void qcom_hwrng_cleanup(struct hwrng *hwrng) > struct qcom_rng *qrng = container_of(hwrng, struct qcom_rng, hwrng); > > clk_disable_unprepare(qrng->clk); > } > > -static int qcom_rng_enable(struct qcom_rng *rng) > -{ > - u32 val; > - int ret; > - > - ret = clk_prepare_enable(rng->clk); > - if (ret) > - return ret; > - > - /* Enable PRNG only if it is not already enabled */ > - val = readl_relaxed(rng->base + PRNG_CONFIG); > - if (val & PRNG_CONFIG_HW_ENABLE) > - goto already_enabled; > - > - val = readl_relaxed(rng->base + PRNG_LFSR_CFG); > - val &= ~PRNG_LFSR_CFG_MASK; > - val |= PRNG_LFSR_CFG_CLOCKS; > - writel(val, rng->base + PRNG_LFSR_CFG); > - > - val = readl_relaxed(rng->base + PRNG_CONFIG); > - val |= PRNG_CONFIG_HW_ENABLE; > - writel(val, rng->base + PRNG_CONFIG); > - > -already_enabled: > - clk_disable_unprepare(rng->clk); > - > - return 0; > -} > - > -static int qcom_rng_init(struct crypto_tfm *tfm) > -{ > - struct qcom_rng_ctx *ctx = crypto_tfm_ctx(tfm); > - > - ctx->rng = qcom_rng_dev; > - > - if (!ctx->rng->match_data->skip_init) > - return qcom_rng_enable(ctx->rng); > - > - return 0; > -} > - > -static struct rng_alg qcom_rng_alg = { > - .generate = qcom_rng_generate, > - .seed = qcom_rng_seed, > - .seedsize = 0, > - .base = { > - .cra_name = "stdrng", > - .cra_driver_name = "qcom-rng", > - .cra_flags = CRYPTO_ALG_TYPE_RNG, > - .cra_priority = 300, > - .cra_ctxsize = sizeof(struct qcom_rng_ctx), > - .cra_module = THIS_MODULE, > - .cra_init = qcom_rng_init, > - } > -}; > - > static int qcom_rng_probe(struct platform_device *pdev) > { > struct qcom_rng *rng; > int ret; > > rng = devm_kzalloc(&pdev->dev, sizeof(*rng), GFP_KERNEL); > if (!rng) > return -ENOMEM; > > - platform_set_drvdata(pdev, rng); > - mutex_init(&rng->lock); > - > rng->base = devm_platform_ioremap_resource(pdev, 0); > if (IS_ERR(rng->base)) > return PTR_ERR(rng->base); > > rng->clk = devm_clk_get_optional(&pdev->dev, "core"); > if (IS_ERR(rng->clk)) > return PTR_ERR(rng->clk); > > - rng->match_data = (struct qcom_rng_match_data *)device_get_match_data(&pdev->dev); > - > - qcom_rng_dev = rng; > - ret = crypto_register_rng(&qcom_rng_alg); > - if (ret) { > - dev_err(&pdev->dev, "Register crypto rng failed: %d\n", ret); > - qcom_rng_dev = NULL; > - return ret; > - } > - > - if (rng->match_data->hwrng_support) { > - rng->hwrng.name = "qcom_hwrng"; > - rng->hwrng.init = qcom_hwrng_init; > - rng->hwrng.read = qcom_hwrng_read; > - rng->hwrng.cleanup = qcom_hwrng_cleanup; > - rng->hwrng.quality = QCOM_TRNG_QUALITY; > - ret = devm_hwrng_register(&pdev->dev, &rng->hwrng); > - if (ret) { > - dev_err(&pdev->dev, "Register hwrng failed: %d\n", ret); > - qcom_rng_dev = NULL; > - goto fail; > - } > - } > - > - return ret; > -fail: > - crypto_unregister_rng(&qcom_rng_alg); > + rng->hwrng.name = "qcom_hwrng"; > + rng->hwrng.init = qcom_hwrng_init; > + rng->hwrng.read = qcom_hwrng_read; > + rng->hwrng.cleanup = qcom_hwrng_cleanup; > + rng->hwrng.quality = QCOM_TRNG_QUALITY; > + ret = devm_hwrng_register(&pdev->dev, &rng->hwrng); > + if (ret) > + dev_err(&pdev->dev, "Register hwrng failed: %d\n", ret); > return ret; > } > > -static void qcom_rng_remove(struct platform_device *pdev) > -{ > - crypto_unregister_rng(&qcom_rng_alg); > - > - qcom_rng_dev = NULL; > -} > - > -static struct qcom_rng_match_data qcom_prng_match_data = { > - .skip_init = false, > - .hwrng_support = false, > -}; > - > -static struct qcom_rng_match_data qcom_prng_ee_match_data = { > - .skip_init = true, > - .hwrng_support = false, > -}; > - > -static struct qcom_rng_match_data qcom_trng_match_data = { > - .skip_init = true, > - .hwrng_support = true, > -}; > - > -static const struct acpi_device_id __maybe_unused qcom_rng_acpi_match[] = { > - { .id = "QCOM8160", .driver_data = (kernel_ulong_t)&qcom_prng_ee_match_data }, > - {} > -}; > -MODULE_DEVICE_TABLE(acpi, qcom_rng_acpi_match); > - > static const struct of_device_id __maybe_unused qcom_rng_of_match[] = { > - { .compatible = "qcom,prng", .data = &qcom_prng_match_data }, > - { .compatible = "qcom,prng-ee", .data = &qcom_prng_ee_match_data }, > - { .compatible = "qcom,trng", .data = &qcom_trng_match_data }, > + { .compatible = "qcom,trng" }, > {} > }; > MODULE_DEVICE_TABLE(of, qcom_rng_of_match); > > static struct platform_driver qcom_rng_driver = { > .probe = qcom_rng_probe, > - .remove = qcom_rng_remove, > .driver = { > .name = KBUILD_MODNAME, > .of_match_table = qcom_rng_of_match, > - .acpi_match_table = ACPI_PTR(qcom_rng_acpi_match), > } > }; > module_platform_driver(qcom_rng_driver); > > MODULE_ALIAS("platform:" KBUILD_MODNAME); > Regards, Neeraj