From nobody Wed Apr 1 21:59:43 2026 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1456142882D; Wed, 1 Apr 2026 13:43:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775051023; cv=none; b=W/wXXZqcbAibC2v9XrGeGELWNi1+HJ4YiSHyB34rcfSWt5RjRP85ih47EpP/EMfaGx/2lSh1F3Z6PId5orG3aGZlVsNn+3haEZcGYWAPWbF/hRhMDxPhCAEQK0tQFa3HaW2Sw4lqumIzf/cLfaLdBNS6gv9DJr/c/pkgZu+HBcY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775051023; c=relaxed/simple; bh=4SZZm3JhKyjaD020mKJyK6ARXZQzN7GM8LgawIblwbI=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=Wr84K5mvPKM74Q2WsF2f2IK66BDWyT1IABVs24eI1eq2XfmFsAgocELcarfG2Br5PonbBXyZLYWf8i41fVMDYWVZGTlQWmONy2rjBIFUhhv6t+qA88uHbqZoTJxSvcfSQMrlzDCyzDXkrcZaJwiPyuCzFBwM8dtlImKFQOKh63E= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BTxjZMUQ; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BTxjZMUQ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 10EDAC2BCB3; Wed, 1 Apr 2026 13:43:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1775051022; bh=4SZZm3JhKyjaD020mKJyK6ARXZQzN7GM8LgawIblwbI=; h=From:Date:Subject:References:In-Reply-To:To:Cc:From; b=BTxjZMUQ/By1avzMYerZzBhGmd+fc96vfb17/1UtE5Yezn70n3f6KZ53RsHPMi/We uQDdLxGRNU8VNPNW/qpKSoWpk+XrlIJ/TnshTpgctWZMC+tPQddTXGq+X7JTUpRztP JO3WFFT31U+ZQ+mRgkAoIgkVVR0V35Zd6+Jl9p1qTBAO7WNpYRTj9NxJh8+ggbJU4g bOKrsMmkTA0Axq/TPk7F4q6GWkSW6GV3+kI6s4aPutbSMvgwznrybsi7tqnRjZ3LSH HygRc7oqBGU5nygSjqmu/QwFxYOR5ZrKC38GmLRQNWJuaHw1I4wrdwdo71s6vW3JW3 kjADDEy/5YA1Q== From: Jeff Layton Date: Wed, 01 Apr 2026 09:43:27 -0400 Subject: [PATCH v6 1/2] firmware_loader: add search_path= module option for multi-path firmware lookup Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260401-fw-path-v6-1-4ebe70441839@kernel.org> References: <20260401-fw-path-v6-0-4ebe70441839@kernel.org> In-Reply-To: <20260401-fw-path-v6-0-4ebe70441839@kernel.org> To: Luis Chamberlain , Russ Weight , Danilo Krummrich , Greg Kroah-Hartman , "Rafael J. Wysocki" , Shuah Khan Cc: Michal Grzedzicki , driver-core@lists.linux.dev, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Jeff Layton X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=10423; i=jlayton@kernel.org; h=from:subject:message-id; bh=4SZZm3JhKyjaD020mKJyK6ARXZQzN7GM8LgawIblwbI=; b=owEBbQKS/ZANAwAKAQAOaEEZVoIVAcsmYgBpzSEML1UzHIzqJdCRXmL0XTQOhBvJ1pBM8VKPd 5dZo7FOZLGJAjMEAAEKAB0WIQRLwNeyRHGyoYTq9dMADmhBGVaCFQUCac0hDAAKCRAADmhBGVaC FV+kD/9DY6sX3GrAWML0dE2cP15w4kzmQHpnHc8/thSSQcHjnFnucXq70URq+jmKsKMJXn/eAZW L5pad6Zaqg6zu7adsF2BN2+4e8us4fvSeBNd3UVLssj/eg0HkpbrpmK9Ddwz6jR+sqqIyuTXs50 i+8KTcIuDMn/Ymdig8guialQPHItvOJY43hwx57v42CwENrtyJLcqlHt44XypZAnhSuhLFnGChJ ncLZ2MfYnQTUM+Z2cwDOyJYB5rq4nzPdZozcRXY74bTb8oQEaW6y/y3padFQxojoiNYt5ZtYjG1 1ovHSgaXklMXlof4L94SKuGLs4+7HUamcc2sxzotRaz872OOzPfjsz+5znrQW0DyTltD6b7V0xg mV1p2O3TsBF2TaSbbDTf7sIrTl7AtxyPEyBtN2km5eWcHFPysm8Dty9FPPeAzbQ30RjL0CQzjAg v5jTaDjx62gPsSr1Jv2QZsUDh/idHgQ7WRCF43Ku7cQ0bj0hB8xp3HFNdYPwlc9pXatlCCk4CEo hAvMcTwyKqso67VNhwOm9JU1881993VWXpH34RwqokS54HMQigOzHlUB862z90fis6kB4ITTme6 clldTJMt75/kzlJ1Wwvkra7f3LPkpjHRcmMcxMB2Hg9VAnu31BashBJjY50EIN13CSKhDiEey+l 3hFjt0Q+MCv6SXw== X-Developer-Key: i=jlayton@kernel.org; a=openpgp; fpr=4BC0D7B24471B2A184EAF5D3000E684119568215 Refactor fw_get_filesystem_firmware() by extracting the per-path firmware loading logic into a new fw_try_firmware_path() helper. Add a new firmware_class.search_path=3D module option that accepts a ':'-separated list of firmware search directories. The input is preprocessed at set time (boot or sysfs write) into a NUL-separated sequence of paths, avoiding per-load parsing overhead. Backslash escapes are supported: '\:' for literal ':', '\\' for literal '\'. The firmware lookup order is: 1. firmware_class.path=3D (single legacy path) 2. firmware_class.search_path=3D (colon-separated paths) 3. Built-in default paths (/lib/firmware/updates/..., /lib/firmware) Example: firmware_class.search_path=3D/custom/path1:/custom/path2 Suggested-by: Michal Grzedzicki Signed-off-by: Jeff Layton --- drivers/base/firmware_loader/main.c | 298 +++++++++++++++++++++++++++-----= ---- 1 file changed, 222 insertions(+), 76 deletions(-) diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_lo= ader/main.c index a11b30dda23be563bd55f25474ceff2153ddd667..06f9530b3eba22187f34416fcd0= 0c1cab8c79291 100644 --- a/drivers/base/firmware_loader/main.c +++ b/drivers/base/firmware_loader/main.c @@ -469,8 +469,9 @@ static int fw_decompress_xz(struct device *dev, struct = fw_priv *fw_priv, =20 /* direct firmware loading support */ static char fw_path_para[256]; +static char fw_search_para[4096]; +static int fw_search_len; static const char * const fw_path[] =3D { - fw_path_para, "/lib/firmware/updates/" UTS_RELEASE, "/lib/firmware/updates", "/lib/firmware/" UTS_RELEASE, @@ -485,6 +486,184 @@ static const char * const fw_path[] =3D { module_param_string(path, fw_path_para, sizeof(fw_path_para), 0644); MODULE_PARM_DESC(path, "customized firmware image search path with a highe= r priority than default path"); =20 +/* + * fw_search_unescape - copy src to dst, processing backslash escapes + * + * Handles '\:' (literal ':') and '\\' (literal '\'). Returns the number + * of bytes written (not counting the trailing NUL). + */ +static int fw_search_unescape(char *dst, int dst_size, const char *src, in= t src_len) +{ + int i, len =3D 0; + + for (i =3D 0; i < src_len && len < dst_size - 1; i++) { + if (src[i] =3D=3D '\\' && i + 1 < src_len && + (src[i + 1] =3D=3D ':' || src[i + 1] =3D=3D '\\')) + i++; + dst[len++] =3D src[i]; + } + dst[len] =3D '\0'; + return len; +} + +/* + * fw_search_set - preprocess a colon-separated search path string + * + * Converts the input into a NUL-separated sequence of paths stored in + * fw_search_para, with fw_search_len tracking the total used length. + * Backslash escapes '\:' (literal ':') and '\\' (literal '\'). + * Trailing newlines on each component are stripped. + */ +static int fw_search_set(const char *val, const struct kernel_param *kp) +{ + int len =3D 0; + + if (!val) { + fw_search_para[0] =3D '\0'; + fw_search_len =3D 0; + return 0; + } + + while (*val) { + const char *sep; + int comp_len, remaining; + + /* find the next unescaped ':' or end of string */ + for (sep =3D val; *sep; sep++) { + if (*sep =3D=3D '\\' && (sep[1] =3D=3D ':' || sep[1] =3D=3D '\\')) + sep++; + else if (*sep =3D=3D ':') + break; + } + + remaining =3D sizeof(fw_search_para) - len - 1; + comp_len =3D fw_search_unescape(fw_search_para + len, remaining, + val, sep - val); + + /* strip trailing newline */ + if (comp_len > 0 && fw_search_para[len + comp_len - 1] =3D=3D '\n') + comp_len--; + + /* only record non-empty components */ + if (comp_len > 0) { + len +=3D comp_len; + fw_search_para[len++] =3D '\0'; + } + + val =3D *sep ? sep + 1 : sep; + } + + /* ensure NUL termination even when empty */ + fw_search_para[len] =3D '\0'; + fw_search_len =3D len; + + return 0; +} + +/* + * fw_search_get - reconstruct colon-separated string for sysfs reads + */ +static int fw_search_get(char *buffer, const struct kernel_param *kp) +{ + const char *p; + int pos =3D 0; + + p =3D fw_search_para; + while (p < fw_search_para + fw_search_len) { + int slen =3D strlen(p); + + if (!slen) + break; + if (pos > 0) + buffer[pos++] =3D ':'; + memcpy(buffer + pos, p, slen); + pos +=3D slen; + p +=3D slen + 1; + } + buffer[pos] =3D '\0'; + return pos; +} + +static const struct kernel_param_ops fw_search_ops =3D { + .set =3D fw_search_set, + .get =3D fw_search_get, +}; +module_param_cb(search_path, &fw_search_ops, NULL, 0644); +MODULE_PARM_DESC(search_path, "colon-separated list of firmware search pat= hs, tried after path=3D (use '\\:' for literal ':', '\\\\' for literal '\\'= )"); + +static int +fw_try_firmware_path(struct device *device, struct fw_priv *fw_priv, + const char *suffix, + int (*decompress)(struct device *dev, + struct fw_priv *fw_priv, + size_t in_size, + const void *in_buffer), + const char *dir, int dirlen, + char *path, void **bufp, size_t msize) +{ + size_t file_size =3D 0; + size_t *file_size_ptr =3D NULL; + size_t size; + int len, rc; + + len =3D snprintf(path, PATH_MAX, "%.*s/%s%s", + dirlen, dir, fw_priv->fw_name, suffix); + if (len >=3D PATH_MAX) + return -ENAMETOOLONG; + + fw_priv->size =3D 0; + + /* + * The total file size is only examined when doing a partial + * read; the "full read" case needs to fail if the whole + * firmware was not completely loaded. + */ + if ((fw_priv->opt_flags & FW_OPT_PARTIAL) && *bufp) + file_size_ptr =3D &file_size; + + /* load firmware files from the mount namespace of init */ + rc =3D kernel_read_file_from_path_initns(path, fw_priv->offset, + bufp, msize, + file_size_ptr, + READING_FIRMWARE); + if (rc < 0) { + if (!(fw_priv->opt_flags & FW_OPT_NO_WARN)) { + if (rc !=3D -ENOENT) + dev_warn(device, + "loading %s failed with error %d\n", + path, rc); + else + dev_dbg(device, + "loading %s failed for no such file or directory.\n", + path); + } + return rc; + } + size =3D rc; + + dev_dbg(device, "Loading firmware from %s\n", path); + if (decompress) { + dev_dbg(device, "f/w decompressing %s\n", + fw_priv->fw_name); + rc =3D decompress(device, fw_priv, size, *bufp); + /* discard the superfluous original content */ + vfree(*bufp); + *bufp =3D NULL; + if (rc) { + fw_free_paged_buf(fw_priv); + return rc; + } + } else { + dev_dbg(device, "direct-loading %s\n", + fw_priv->fw_name); + if (!fw_priv->data) + fw_priv->data =3D *bufp; + fw_priv->size =3D size; + } + fw_state_done(fw_priv); + return 0; +} + static int fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv, const char *suffix, @@ -493,10 +672,9 @@ fw_get_filesystem_firmware(struct device *device, stru= ct fw_priv *fw_priv, size_t in_size, const void *in_buffer)) { - size_t size; - int i, len, maxlen =3D 0; + int i; int rc =3D -ENOENT; - char *path, *nt =3D NULL; + char *path; size_t msize =3D INT_MAX; void *buffer =3D NULL; =20 @@ -511,83 +689,51 @@ fw_get_filesystem_firmware(struct device *device, str= uct fw_priv *fw_priv, return -ENOMEM; =20 wait_for_initramfs(); - for (i =3D 0; i < ARRAY_SIZE(fw_path); i++) { - size_t file_size =3D 0; - size_t *file_size_ptr =3D NULL; - - /* skip the unset customized path */ - if (!fw_path[i][0]) - continue; - - /* strip off \n from customized path */ - maxlen =3D strlen(fw_path[i]); - if (i =3D=3D 0) { - nt =3D strchr(fw_path[i], '\n'); - if (nt) - maxlen =3D nt - fw_path[i]; - } =20 - len =3D snprintf(path, PATH_MAX, "%.*s/%s%s", - maxlen, fw_path[i], - fw_priv->fw_name, suffix); - if (len >=3D PATH_MAX) { - rc =3D -ENAMETOOLONG; - break; - } + /* Try the customized path first */ + if (fw_path_para[0]) { + int dirlen =3D strlen(fw_path_para); =20 - fw_priv->size =3D 0; + /* strip trailing newline */ + if (fw_path_para[dirlen - 1] =3D=3D '\n') + dirlen--; =20 - /* - * The total file size is only examined when doing a partial - * read; the "full read" case needs to fail if the whole - * firmware was not completely loaded. - */ - if ((fw_priv->opt_flags & FW_OPT_PARTIAL) && buffer) - file_size_ptr =3D &file_size; - - /* load firmware files from the mount namespace of init */ - rc =3D kernel_read_file_from_path_initns(path, fw_priv->offset, - &buffer, msize, - file_size_ptr, - READING_FIRMWARE); - if (rc < 0) { - if (!(fw_priv->opt_flags & FW_OPT_NO_WARN)) { - if (rc !=3D -ENOENT) - dev_warn(device, - "loading %s failed with error %d\n", - path, rc); - else - dev_dbg(device, - "loading %s failed for no such file or directory.\n", - path); - } - continue; - } - size =3D rc; - rc =3D 0; - - dev_dbg(device, "Loading firmware from %s\n", path); - if (decompress) { - dev_dbg(device, "f/w decompressing %s\n", - fw_priv->fw_name); - rc =3D decompress(device, fw_priv, size, buffer); - /* discard the superfluous original content */ - vfree(buffer); - buffer =3D NULL; - if (rc) { - fw_free_paged_buf(fw_priv); - continue; - } - } else { - dev_dbg(device, "direct-loading %s\n", - fw_priv->fw_name); - if (!fw_priv->data) - fw_priv->data =3D buffer; - fw_priv->size =3D size; + rc =3D fw_try_firmware_path(device, fw_priv, suffix, decompress, + fw_path_para, dirlen, + path, &buffer, msize); + if (!rc) + goto done; + } + + /* Try each preprocessed NUL-separated path in fw_search_para */ + if (fw_search_len > 0) { + const char *p =3D fw_search_para; + + while (p < fw_search_para + fw_search_len) { + int dirlen =3D strlen(p); + + if (!dirlen) + break; + rc =3D fw_try_firmware_path(device, fw_priv, + suffix, decompress, + p, dirlen, + path, &buffer, msize); + if (!rc) + goto done; + p +=3D dirlen + 1; } - fw_state_done(fw_priv); - break; } + + /* Try default firmware paths */ + for (i =3D 0; i < ARRAY_SIZE(fw_path); i++) { + rc =3D fw_try_firmware_path(device, fw_priv, suffix, decompress, + fw_path[i], strlen(fw_path[i]), + path, &buffer, msize); + if (!rc) + break; + } + +done: __putname(path); =20 return rc; --=20 2.53.0