From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx488AtkEhn7el/I6uzb1lePY6JcCaXSVkaRBZqSmzwwXLRvNU5AdpXQtI+z8FmCU0oVmdiDF ARC-Seal: i=1; a=rsa-sha256; t=1523408664; cv=none; d=google.com; s=arc-20160816; b=hBVHKKZ6R7LDCPMWus0OxEq62ElS0mby30R6khPMdcqdcyzBFwvHoZhU6LE6cEcBE8 Y+s4uS+B4PkIxHROSBmptNzTjDwBlLUO0MDpxvicW2YRw9sBw77xxPmdj0ejqB2eFGc9 AW5By3v0viQ2n2qkiwIKJob36Q7J+EKJbwmJiaP2nDiqwd0E3TOK6aSRVdxNIC6mXrn2 I04ujZLckZMT3Ywt22fz4pK5dqgTbklOkqcW+CROQytuYq2jrPOYVb+H2p/7Z/waTRNR RrqVhx6NjhYkNuMLzyqOXG7SNaIPyTc/nR+C61wnJEpqmYubhQqCFwcKm8OQghj7jKhY odAA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=message-id:date:subject:cc:to:from:delivered-to:list-id :list-subscribe:list-unsubscribe:list-help:list-post:precedence :mailing-list:arc-authentication-results; bh=qZtCb8WTK8SD0ZYyNTlFNJ8k3oiY7Jz5Pa30z2IYpAE=; b=UIqIBm6Dr1wzUjpWi2WXP3dYMnoC83jMnZxwFQxxW6ekFizxskZ8THfXxKoLYjFHD5 hIEH4qow+2hGNfGTHmCC8xnFHIHaC9vNRLnGANcK5DkYTc/WE7XNnlG6W1iDYn6xSb5x hxwGLtbR+82KFP3TbrPhnsbrk+l1rGMjJvaLuoCeQMMXB1A/29csJ1+1mC7Ni1eI0Iat PMvPA4fe7R0hmyO4YTBgYL9p+x9aSRBRhJHC7EZGffxpBxfuQ4tbJ5E7BOZ8X4OLqIWD c/jNEvDdExN2WcDIu4hsh4uEkmjrIMifeYQdzIRildszaxZONuTe6QUStHwE0UKlHobE 3+Mw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of kernel-hardening-return-12967-gregkh=linuxfoundation.org@lists.openwall.com designates 195.42.179.200 as permitted sender) smtp.mailfrom=kernel-hardening-return-12967-gregkh=linuxfoundation.org@lists.openwall.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of kernel-hardening-return-12967-gregkh=linuxfoundation.org@lists.openwall.com designates 195.42.179.200 as permitted sender) smtp.mailfrom=kernel-hardening-return-12967-gregkh=linuxfoundation.org@lists.openwall.com; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm List-Post: List-Help: List-Unsubscribe: List-Subscribe: From: Laura Abbott To: Linus Walleij , Kees Cook , Lukas Wunner , Rasmus Villemoes Cc: Laura Abbott , linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: [PATCHv4] gpio: Remove VLA from gpiolib Date: Tue, 10 Apr 2018 18:03:52 -0700 Message-Id: <20180411010352.17929-1-labbott@redhat.com> X-Mailer: git-send-email 2.14.3 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1597409764349726473?= X-GMAIL-MSGID: =?utf-8?q?1597409764349726473?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: The new challenge is to remove VLAs from the kernel (see https://lkml.org/lkml/2018/3/7/621) to eventually turn on -Wvla. Using a kmalloc array is the easy way to fix this but kmalloc is still more expensive than stack allocation. Introduce a fast path with a fixed size stack array to cover most chip with gpios below some fixed amount. The slow path dynamically allocates an array to cover those chips with a large number of gpios. Reviewed-and-tested-by: Lukas Wunner Signed-off-by: Lukas Wunner Signed-off-by: Laura Abbott --- v4: Changed some local variables to avoid coccinelle warnings. Added a warning if the number of GPIOs exceeds the current fast path define. Lukas, I kept your Tested-by because the changes were pretty minimal. Let me know if you want to run the tests again. --- drivers/gpio/gpiolib.c | 89 ++++++++++++++++++++++++++++++++++--------- drivers/gpio/gpiolib.h | 2 +- include/linux/gpio/consumer.h | 10 +++-- 3 files changed, 79 insertions(+), 22 deletions(-) diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index d66de67ef307..b6605255662e 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -61,6 +61,11 @@ static struct bus_type gpio_bus_type = { .name = "gpio", }; +/* + * Number of GPIOs to use for the fast path in set array + */ +#define FASTPATH_NGPIO 256 + /* gpio_lock prevents conflicts during gpio_desc[] table updates. * While any GPIO is requested, its gpio_chip is not removable; * each GPIO's "requested" flag serves as a lock and refcount. @@ -399,12 +404,11 @@ static long linehandle_ioctl(struct file *filep, unsigned int cmd, vals[i] = !!ghd.values[i]; /* Reuse the array setting function */ - gpiod_set_array_value_complex(false, + return gpiod_set_array_value_complex(false, true, lh->numdescs, lh->descs, vals); - return 0; } return -EINVAL; } @@ -1192,6 +1196,10 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data, goto err_free_descs; } + if (chip->ngpio > FASTPATH_NGPIO) + chip_warn(chip, "line cnt %d is greater than fast path cnt %d\n", + chip->ngpio, FASTPATH_NGPIO); + gdev->label = kstrdup_const(chip->label ?: "unknown", GFP_KERNEL); if (!gdev->label) { status = -ENOMEM; @@ -2653,6 +2661,7 @@ static int gpio_chip_get_multiple(struct gpio_chip *chip, return -EIO; } + int gpiod_get_array_value_complex(bool raw, bool can_sleep, unsigned int array_size, struct gpio_desc **desc_array, @@ -2662,16 +2671,28 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep, while (i < array_size) { struct gpio_chip *chip = desc_array[i]->gdev->chip; - unsigned long mask[BITS_TO_LONGS(chip->ngpio)]; - unsigned long bits[BITS_TO_LONGS(chip->ngpio)]; + unsigned long fastpath[2 * BITS_TO_LONGS(FASTPATH_NGPIO)]; + unsigned long *mask, *bits; int first, j, ret; + if (likely(chip->ngpio <= FASTPATH_NGPIO)) { + memset(fastpath, 0, sizeof(fastpath)); + mask = fastpath; + bits = fastpath + BITS_TO_LONGS(FASTPATH_NGPIO); + } else { + mask = kcalloc(2 * BITS_TO_LONGS(chip->ngpio), + sizeof(*mask), + can_sleep ? GFP_KERNEL : GFP_ATOMIC); + if (!mask) + return -ENOMEM; + bits = mask + BITS_TO_LONGS(chip->ngpio); + } + if (!can_sleep) WARN_ON(chip->can_sleep); /* collect all inputs belonging to the same chip */ first = i; - memset(mask, 0, sizeof(mask)); do { const struct gpio_desc *desc = desc_array[i]; int hwgpio = gpio_chip_hwgpio(desc); @@ -2682,8 +2703,15 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep, (desc_array[i]->gdev->chip == chip)); ret = gpio_chip_get_multiple(chip, mask, bits); - if (ret) + if (ret) { + /* + * Go against style and intentionally do the check for + * performance reasons + */ + if (mask != fastpath) + kfree(mask); return ret; + } for (j = first; j < i; j++) { const struct gpio_desc *desc = desc_array[j]; @@ -2695,6 +2723,13 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep, value_array[j] = value; trace_gpio_value(desc_to_gpio(desc), 1, value); } + + /* + * Go against style and intentionally do the check for + * performance reasons + */ + if (mask != fastpath) + kfree(mask); } return 0; } @@ -2878,7 +2913,7 @@ static void gpio_chip_set_multiple(struct gpio_chip *chip, } } -void gpiod_set_array_value_complex(bool raw, bool can_sleep, +int gpiod_set_array_value_complex(bool raw, bool can_sleep, unsigned int array_size, struct gpio_desc **desc_array, int *value_array) @@ -2887,14 +2922,26 @@ void gpiod_set_array_value_complex(bool raw, bool can_sleep, while (i < array_size) { struct gpio_chip *chip = desc_array[i]->gdev->chip; - unsigned long mask[BITS_TO_LONGS(chip->ngpio)]; - unsigned long bits[BITS_TO_LONGS(chip->ngpio)]; + unsigned long fastpath[2 * BITS_TO_LONGS(FASTPATH_NGPIO)]; + unsigned long *mask, *bits; int count = 0; + if (likely(chip->ngpio <= FASTPATH_NGPIO)) { + memset(fastpath, 0, sizeof(fastpath)); + mask = fastpath; + bits = fastpath + BITS_TO_LONGS(FASTPATH_NGPIO); + } else { + mask = kcalloc(2 * BITS_TO_LONGS(chip->ngpio), + sizeof(*mask), + can_sleep ? GFP_KERNEL : GFP_ATOMIC); + if (!mask) + return -ENOMEM; + bits = mask + BITS_TO_LONGS(chip->ngpio); + } + if (!can_sleep) WARN_ON(chip->can_sleep); - memset(mask, 0, sizeof(mask)); do { struct gpio_desc *desc = desc_array[i]; int hwgpio = gpio_chip_hwgpio(desc); @@ -2925,7 +2972,15 @@ void gpiod_set_array_value_complex(bool raw, bool can_sleep, /* push collected bits to outputs */ if (count != 0) gpio_chip_set_multiple(chip, mask, bits); + + /* + * Go against style and intentionally do the check for + * performance reasons + */ + if (mask != fastpath) + kfree(mask); } + return 0; } /** @@ -3000,13 +3055,13 @@ EXPORT_SYMBOL_GPL(gpiod_set_value); * This function should be called from contexts where we cannot sleep, and will * complain if the GPIO chip functions potentially sleep. */ -void gpiod_set_raw_array_value(unsigned int array_size, +int gpiod_set_raw_array_value(unsigned int array_size, struct gpio_desc **desc_array, int *value_array) { if (!desc_array) - return; - gpiod_set_array_value_complex(true, false, array_size, desc_array, - value_array); + return -EINVAL; + return gpiod_set_array_value_complex(true, false, array_size, + desc_array, value_array); } EXPORT_SYMBOL_GPL(gpiod_set_raw_array_value); @@ -3326,14 +3381,14 @@ EXPORT_SYMBOL_GPL(gpiod_set_value_cansleep); * * This function is to be called from contexts that can sleep. */ -void gpiod_set_raw_array_value_cansleep(unsigned int array_size, +int gpiod_set_raw_array_value_cansleep(unsigned int array_size, struct gpio_desc **desc_array, int *value_array) { might_sleep_if(extra_checks); if (!desc_array) - return; - gpiod_set_array_value_complex(true, true, array_size, desc_array, + return -EINVAL; + return gpiod_set_array_value_complex(true, true, array_size, desc_array, value_array); } EXPORT_SYMBOL_GPL(gpiod_set_raw_array_value_cansleep); diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index b17ec6795c81..b64813e3876e 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -188,7 +188,7 @@ int gpiod_get_array_value_complex(bool raw, bool can_sleep, unsigned int array_size, struct gpio_desc **desc_array, int *value_array); -void gpiod_set_array_value_complex(bool raw, bool can_sleep, +int gpiod_set_array_value_complex(bool raw, bool can_sleep, unsigned int array_size, struct gpio_desc **desc_array, int *value_array); diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h index dbd065963296..243112c7fa7d 100644 --- a/include/linux/gpio/consumer.h +++ b/include/linux/gpio/consumer.h @@ -116,7 +116,7 @@ int gpiod_get_raw_array_value(unsigned int array_size, struct gpio_desc **desc_array, int *value_array); void gpiod_set_raw_value(struct gpio_desc *desc, int value); -void gpiod_set_raw_array_value(unsigned int array_size, +int gpiod_set_raw_array_value(unsigned int array_size, struct gpio_desc **desc_array, int *value_array); @@ -134,7 +134,7 @@ int gpiod_get_raw_array_value_cansleep(unsigned int array_size, struct gpio_desc **desc_array, int *value_array); void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, int value); -void gpiod_set_raw_array_value_cansleep(unsigned int array_size, +int gpiod_set_raw_array_value_cansleep(unsigned int array_size, struct gpio_desc **desc_array, int *value_array); @@ -369,12 +369,13 @@ static inline void gpiod_set_raw_value(struct gpio_desc *desc, int value) /* GPIO can never have been requested */ WARN_ON(1); } -static inline void gpiod_set_raw_array_value(unsigned int array_size, +static inline int gpiod_set_raw_array_value(unsigned int array_size, struct gpio_desc **desc_array, int *value_array) { /* GPIO can never have been requested */ WARN_ON(1); + return 0; } static inline int gpiod_get_value_cansleep(const struct gpio_desc *desc) @@ -423,12 +424,13 @@ static inline void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, /* GPIO can never have been requested */ WARN_ON(1); } -static inline void gpiod_set_raw_array_value_cansleep(unsigned int array_size, +static inline int gpiod_set_raw_array_value_cansleep(unsigned int array_size, struct gpio_desc **desc_array, int *value_array) { /* GPIO can never have been requested */ WARN_ON(1); + return 0; } static inline int gpiod_set_debounce(struct gpio_desc *desc, unsigned debounce) -- 2.14.3