From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj2-f9.google.com (mail-pj2-f9.google.com [74.125.227.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 11DB13195FE for ; Fri, 9 Oct 2026 02:16:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.227.137 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791512214; cv=none; b=CIDOiWQ6eh1kkZuNtP5GghtTHGgJgsX/9z3CHSRxE+wASXrbqT21k+Dry9yfGPqTIn4TduZU+SFDCwkTh7sXf4YH2iit3iBR5W14E+PNXMYhpepaqUKqjPFVyOb+wCAKywOvOQrDFobEUa47izltjuiIVr8Iq3Br5tJw4LIIK7I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791512214; c=relaxed/simple; bh=RgfS304p5sNqkKLM5WXwpFaV9IC+O6sYdi07k4m47TY=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kKOJN447l3/TO6tgLa2RRobzqTzj5PxP3AciL5NO8fp3DxwgRLvjKLuiGHEdHxo/ir8ZSnLLDH7q9LI3iUjBqoN8TcM4uMv/ab1WNoJ4vl2ocDPufpc3A2QE8olxI5e5q2LWWuJ11uilN5tPonclmJubF6zIr2y/GK7zv2pcEtI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=flUtDwnH; arc=none smtp.client-ip=74.125.227.137 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="flUtDwnH" Received: by mail-pj2-f9.google.com with SMTP id 98e67ed59e1d1-3a51696a650so3260058a91.1 for ; Thu, 08 Oct 2026 19:16:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1791512211; x=1792117011; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to :content-type; bh=3HzF21b7wH+OCi6BgDNq8o3oZ/2tI5ENlGWlmHfz0R4=; b=flUtDwnHsqUfPppsWxHIIOWVeGy04k0lXEII4Xm74a4mWqGHlcQhwq7WM5YwDSLYhT wTvhoXzvEfKJ7ZHYY497rYDY35GnE5qoU1R52idWPzZkP1pfry+XMtjjpk7NXGnesMI7 F7u342Y3vhPV8LvWzVA8UKBT7RxHePsdkjO5Z0VF4713077aH+FsYfbG1Fszsw7pmvKJ 8/xyaXzKN630pcmFCItA/u1buHHemLIUDtgg/OCHAvZWHpa4X5/81nlSYO1CHzsYoWTR gX8xZphgYlBOlgb0vJHoq5qt9XPG7KfYUxdg8ktRlTJh0saq0To1JwJz/wCscIg8kKl1 nlmA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1791512211; x=1792117011; h=content-transfer-encoding:content-type:in-reply-to:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=3HzF21b7wH+OCi6BgDNq8o3oZ/2tI5ENlGWlmHfz0R4=; b=SFDJguWqE2sZyVkb0BC/159dlYJ9BOz/UO5r920jk67trRp6088FPsEpDQ13SJpTxl vyJ/1HgrlZb+kduUEPosq8xBwEPBxNWKxbI6/S12QG3G4k6XmgQX4gC8gn7bZrjpNcfX NDySou8YhfrEYRYRhLIA4J92maRGoGKcjBXfznFJmvlfTBUxB0DFx0QXi3ezDW+BhBbG 8/RJ5WQqRcBzwL6KyQ6QwDaJmhpIx5rm3Dr9XtoREcQfK5ICAgdSql+qaMj/Bs+/capE WKhRqNb/IBj1vJL4VkWxVTXIj4HT6fcVRwNwFt1UBxvyNaAHdFNGCnKhkIRXrRxU9fRW 43eQ== X-Forwarded-Encrypted: i=1; AKwUvBxukkUuAkN7YNvFkKhSRhaxZ+nC+s2vw8Gl8ca+XvWjGtYYcdkG+tX3oar7n7MGWRkOmS6gyZ2+EvV8@vger.kernel.org X-Gm-Message-State: AFq9FYI76z7U1Vj5NH4hghXmjw6tsbsm+zY4JhcK9NfIt61/Qsgb6ACW nch1d/0hiEljcopBfMlXXmo/+Lby5+xP/qI+S7YzSdaDS7u4QrXPpj5d X-Gm-Gg: AYBFou1W1lhFsj49sj5GjSxQEfqSVMnYUH0k8dDww/ewA944Qxr3D9XKh6LnNT7JAh6 NLL47R9PeOnwxP8a8Xl2+Z3kwP9wAPHrr1OXmC0i4s6ba6y5bNTpTpl2sr8Y28pBnr8o5EIADtO fs0DT9WGO0oHtLkA837KJFH7sVPzhOwP2mZesgWxC0RZtUUmYxGT3UMFY2wUSbpZ9ERIOf5DN20 0X1jF13zo/360WuiWv8bj0Hh11rbLKupvXoyEMPmtmB56ljp9ZLaYNLktC9aa/ullN9uLyElUG2 uohgvYzszBjsjwnnSs7sqdQk35tdGUZQknq+gsWGIi90e4f/LIdkSgs7T046MFLBM6XlNGUTPlG YVuTdCL2l0YkYNIbOYBhsNyIaAV/Wr0hniTpuaKiHRkNeD+sIcMEorpTfyi+yQhFLzpYkBfLoJw 7np2OM2lllI7rY86meLSuUmZ6dpmxvb7qMYlnJ8wJiG1X8kdI0chsr0knh+xhSxrvqha3tiLh12 hLQ7Q== X-Received: by 2002:a17:90b:1d4f:b0:3aa:6b5d:a00a with SMTP id 98e67ed59e1d1-3ab3ac7912fmr583653a91.53.1791512211401; Thu, 08 Oct 2026 19:16:51 -0700 (PDT) Received: from [10.125.112.22] ([122.11.210.25]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3ab36ed040dsm1605868a91.6.2026.10.08.19.16.46 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 08 Oct 2026 19:16:50 -0700 (PDT) Message-ID: Date: Fri, 9 Oct 2026 10:16:44 +0800 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 2/2] of: reserved_mem: allocate and map the reserved_mem array early To: Marek Szyprowski , linux-mm@kvack.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Mike Rapoport , Rob Herring , Saravana Kannan , Oreoluwa Babatunde , Andrew Morton References: <20261008152403.766439-1-m.szyprowski@samsung.com> <20261008152403.766439-3-m.szyprowski@samsung.com> Content-Language: en-US From: Wandun In-Reply-To: <20261008152403.766439-3-m.szyprowski@samsung.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 10/8/26 23:24, Marek Szyprowski wrote: > Get rid of the static, limited-size reserved_mem array and replace it > with array allocated by memblock_alloc_raw() and accessed through a > temporary early_memremap() mapping. Such mapping is needed for some > architectures (like ARM64), where linear map is not yet available during > early boot scan. Having a single, writeable array with all reserved > regions removes the need to perform two step initialization introduced > by commit 8a6e02d0c00e ("of: reserved_mem: Restructure how the reserved > memory regions are processed"), so all regions can be processed > directly during the early scan again. One concern about the ordering here: the new memblock_alloc_raw() for the reserved_mem array runs *before* the static ("reg") regions are reserved, so the array can be allocated from inside one of them which makes the subsequent static region reservation fail. Best regards, Wandun > > Suggested-by: Mike Rapoport > Link: https://lore.kernel.org/all/asc6brs_g0ky0wOM@kernel.org/ > Assisted-By: LLM > Signed-off-by: Marek Szyprowski > --- > drivers/of/fdt.c | 3 - > drivers/of/of_private.h | 2 - > drivers/of/of_reserved_mem.c | 247 +++++++++++++---------------------- > 3 files changed, 92 insertions(+), 160 deletions(-) > > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > index ecc923102622..a58efdcbac7f 100644 > --- a/drivers/of/fdt.c > +++ b/drivers/of/fdt.c > @@ -1283,9 +1283,6 @@ void __init unflatten_device_tree(void) > { > void *fdt = initial_boot_params; > > - /* Save the statically-placed regions in the reserved_mem array */ > - fdt_scan_reserved_mem_late(); > - > /* Populate an empty root node when bootloader doesn't provide one */ > if (!fdt) { > fdt = (void *) __dtb_empty_root_begin; > diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h > index 0ae16da066e2..895f868b4cfa 100644 > --- a/drivers/of/of_private.h > +++ b/drivers/of/of_private.h > @@ -9,7 +9,6 @@ > */ > > #define FDT_ALIGN_SIZE 8 > -#define MAX_RESERVED_REGIONS 64 > > /** > * struct alias_prop - Alias property in 'aliases' node > @@ -186,7 +185,6 @@ static inline struct device_node *__of_get_dma_parent(const struct device_node * > #endif > > int fdt_scan_reserved_mem(void); > -void __init fdt_scan_reserved_mem_late(void); > > bool of_fdt_device_is_available(const void *blob, unsigned long node); > > diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c > index 300fb236ab59..8d8fa7242d4a 100644 > --- a/drivers/of/of_reserved_mem.c > +++ b/drivers/of/of_reserved_mem.c > @@ -24,12 +24,12 @@ > #include > #include > #include > +#include > > #include "of_private.h" > > -static struct reserved_mem reserved_mem_array[MAX_RESERVED_REGIONS] __initdata; > -static struct reserved_mem *reserved_mem __refdata = reserved_mem_array; > -static int total_reserved_mem_cnt = MAX_RESERVED_REGIONS; > +static struct reserved_mem *reserved_mem __refdata; > +static int total_reserved_mem_cnt; > static int reserved_mem_count; > > static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size, > @@ -59,56 +59,46 @@ static int __init early_init_dt_alloc_reserved_memory_arch(phys_addr_t size, > } > > /* > - * alloc_reserved_mem_array() - allocate memory for the reserved_mem > - * array using memblock > + * reserved_mem_array_map() - make the freshly allocated reserved_mem array > + * accessible during early boot > * > - * This function is used to allocate memory for the reserved_mem > - * array according to the total number of reserved memory regions > - * defined in the DT. > - * After the new array is allocated, the information stored in > - * the initial static array is copied over to this new array and > - * the new array is used from this point on. > + * On some architectures (i.e. ARM64) the linear mapping is not yet usable when > + * the reserved memory regions are scanned, so the array has to be accessed > + * through a temporary early mapping. > */ > -static int __init alloc_reserved_mem_array(void) > +static struct reserved_mem * __init reserved_mem_array_map(struct reserved_mem *array, > + size_t size) > { > - struct reserved_mem *new_array; > - size_t alloc_size, copy_size, memset_size; > - int ret; > + if (IS_ENABLED(CONFIG_GENERIC_EARLY_IOREMAP)) > + return early_memremap(__pa(array), size); > + else > + return array; > +} > > - if (!total_reserved_mem_cnt) > - return 0; > +static void __init reserved_mem_array_unmap(struct reserved_mem *map, size_t size) > +{ > + if (IS_ENABLED(CONFIG_GENERIC_EARLY_IOREMAP)) > + early_memunmap(map, size); > +} > > - alloc_size = array_size(total_reserved_mem_cnt, sizeof(*new_array)); > - if (alloc_size == SIZE_MAX) { > - ret = -EOVERFLOW; > - goto fail; > - } > +/* > + * count_reserved_mem_nodes() - count the nodes that might need an entry in the > + * reserved_mem array > + */ > +static int __init count_reserved_mem_nodes(const void *fdt, int node) > +{ > + int child, len, count = 0; > > - new_array = memblock_alloc(alloc_size, SMP_CACHE_BYTES); > - if (!new_array) { > - ret = -ENOMEM; > - goto fail; > - } > + fdt_for_each_subnode(child, fdt, node) { > + if (!of_fdt_device_is_available(fdt, child)) > + continue; > > - copy_size = array_size(reserved_mem_count, sizeof(*new_array)); > - if (copy_size == SIZE_MAX) { > - memblock_free(new_array, alloc_size); > - ret = -EOVERFLOW; > - goto fail; > + /* static regions use 'reg', dynamic ones use 'size' */ > + if ((of_flat_dt_get_addr_size_prop(child, "reg", &len) && len) || > + (of_get_flat_dt_prop(child, "size", &len) && len)) > + count++; > } > - > - memset_size = alloc_size - copy_size; > - > - memcpy(new_array, reserved_mem, copy_size); > - memset(new_array + reserved_mem_count, 0, memset_size); > - > - reserved_mem = new_array; > - return 0; > - > -fail: > - pr_err("Failed to allocate memory for reserved_mem array with err: %d", ret); > - reserved_mem_count = 0; > - return ret; > + return count; > } > > static void fdt_init_reserved_mem_node(unsigned long node, const char *uname, > @@ -169,6 +159,7 @@ static int __init __reserved_mem_reserve_reg(unsigned long node, > > if (size && early_init_dt_reserve_memory(base, size, nomap) == 0) { > fdt_fixup_reserved_mem_node(node, base, size); > + fdt_init_reserved_mem_node(node, uname, base, size); > pr_debug("Reserved memory: reserved region for node '%s': base %pa, size %lu MiB\n", > uname, &base, (unsigned long)(size / SZ_1M)); > } else { > @@ -381,143 +372,89 @@ static void __init __rmem_check_for_overlap(void) > } > } > > -/** > - * fdt_scan_reserved_mem_late() - Scan FDT and initialize remaining reserved > - * memory regions. > - * > - * This function is used to scan again through the DT and initialize the > - * "static" reserved memory regions, that are defined using the "reg" > - * property. Each such region is then initialized with its specific init > - * function and stored in the global reserved_mem array. > - */ > -void __init fdt_scan_reserved_mem_late(void) > -{ > - const void *fdt = initial_boot_params; > - phys_addr_t base, size; > - int node, child; > - > - if (!fdt) > - return; > - > - node = fdt_path_offset(fdt, "/reserved-memory"); > - if (node < 0) { > - pr_info("Reserved memory: No reserved-memory node in the DT\n"); > - return; > - } > - > - /* Attempt dynamic allocation of a new reserved_mem array */ > - if (alloc_reserved_mem_array()) > - return; > - > - if (__reserved_mem_check_root(node)) { > - pr_err("Reserved memory: unsupported node format, ignoring\n"); > - return; > - } > - > - fdt_for_each_subnode(child, fdt, node) { > - const __be32 *prop; > - const char *uname; > - u64 b, s; > - int ret; > - int len; > - > - if (!of_fdt_device_is_available(fdt, child)) > - continue; > - > - prop = of_flat_dt_get_addr_size_prop(child, "reg", &len); > - if (!prop || !len) > - continue; > - > - ret = fdt_validate_reserved_mem_node(child, NULL); > - if (ret && ret != -ENODEV) > - continue; > - > - of_flat_dt_read_addr_size(prop, 0, &b, &s); > - base = b; > - size = s; > - > - if (size) { > - uname = fdt_get_name(fdt, child, NULL); > - fdt_init_reserved_mem_node(child, uname, base, size); > - } > - } > - > - /* check for overlapping reserved regions */ > - __rmem_check_for_overlap(); > -} > > /* > * fdt_scan_reserved_mem() - reserve and allocate memory occupied by > * reserved memory regions. > * > - * This function is used to scan through the FDT and mark memory occupied > - * by all static (defined by the "reg" property) reserved memory regions. > - * Then memory for all dynamic regions (defined by size & alignment) is > - * allocated, a region specific init function is called and region information > - * is stored in the reserved_mem array. > + * This function is used to scan through the FDT and count the number of > + * reserved memory regions, so the reserved_mem array can be allocated with > + * the exact size. Then all static (defined by the "reg" property) reserved > + * memory regions are marked as reserved, memory for all dynamic regions > + * (defined by size & alignment) is allocated, a region specific init function > + * is called and region information is stored in the reserved_mem array. > */ > int __init fdt_scan_reserved_mem(void) > { > - int node, child; > - int dynamic_nodes_cnt = 0, count = 0; > - int dynamic_nodes[MAX_RESERVED_REGIONS]; > + struct reserved_mem *array, *map; > + size_t array_bytes; > + int node, child, cnt; > const void *fdt = initial_boot_params; > > node = fdt_path_offset(fdt, "/reserved-memory"); > - if (node < 0) { > - total_reserved_mem_cnt = 0; > + if (node < 0) > return -ENODEV; > - } > > if (__reserved_mem_check_root(node) != 0) { > pr_err("Reserved memory: unsupported node format, ignoring\n"); > - total_reserved_mem_cnt = 0; > return -EINVAL; > } > > - fdt_for_each_subnode(child, fdt, node) { > - const char *uname; > - int err; > + /* First pass: count the entries needed for the reserved_mem array */ > + cnt = count_reserved_mem_nodes(fdt, node); > + if (!cnt) > + return 0; > > - if (!of_fdt_device_is_available(fdt, child)) > - continue; > + array_bytes = array_size(cnt, sizeof(*array)); > + array = memblock_alloc_raw(array_bytes, SMP_CACHE_BYTES); > + if (!array) { > + pr_err("Failed to allocate memory for reserved_mem array\n"); > + return -ENOMEM; > + } > > - uname = fdt_get_name(fdt, child, NULL); > + map = reserved_mem_array_map(array, array_bytes); > + if (!map) { > + pr_err("Failed to map memory for reserved_mem array\n"); > + memblock_free(array, array_bytes); > + return -ENOMEM; > + } > + memset(map, 0, array_bytes); > > - err = __reserved_mem_reserve_reg(child, uname); > - if (!err) > - count++; > + reserved_mem = map; > + total_reserved_mem_cnt = cnt; > > - /* > - * Save the nodes for the dynamically-placed regions > - * into an array which will be used for allocation right > - * after all the statically-placed regions are reserved > - * or marked as no-map. This is done to avoid dynamically > - * allocating from one of the statically-placed regions. > - */ > - if (err != -ENOENT || !of_get_flat_dt_prop(child, "size", NULL)) > + /* Second pass: reserve and initialize the static regions */ > + fdt_for_each_subnode(child, fdt, node) { > + if (!of_fdt_device_is_available(fdt, child)) > continue; > > - if (dynamic_nodes_cnt == MAX_RESERVED_REGIONS) { > - pr_err("too many defined dynamic regions, skip '%s'\n", > - uname); > + __reserved_mem_reserve_reg(child, > + fdt_get_name(fdt, child, NULL)); > + } > + > + /* > + * Allocate the dynamically-placed regions only after all the > + * statically-placed regions are reserved or marked as no-map. This > + * is done to avoid dynamically allocating from one of the > + * statically-placed regions. > + */ > + fdt_for_each_subnode(child, fdt, node) { > + int len; > + > + if (!of_fdt_device_is_available(fdt, child) || > + (of_flat_dt_get_addr_size_prop(child, "reg", &len) && len)) > continue; > - } > > - dynamic_nodes[dynamic_nodes_cnt] = child; > - dynamic_nodes_cnt++; > - } > - for (int i = 0; i < dynamic_nodes_cnt; i++) { > - const char *uname; > - int err; > - > - child = dynamic_nodes[i]; > - uname = fdt_get_name(fdt, child, NULL); > - err = __reserved_mem_alloc_size(child, uname); > - if (!err) > - count++; > + __reserved_mem_alloc_size(child, > + fdt_get_name(fdt, child, NULL)); > } > - total_reserved_mem_cnt = count; > + > + /* check for overlapping reserved regions */ > + __rmem_check_for_overlap(); > + > + /* Switch to the permanent address of the array */ > + reserved_mem_array_unmap(map, array_bytes); > + reserved_mem = array; > return 0; > } >