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Tue, 28 Apr 2026 23:59:42 -0700 (PDT) From: Chen Wandun X-Google-Original-From: Chen Wandun To: kexec@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, loongarch@lists.linux.dev, linux-riscv@lists.infradead.org, devicetree@vger.kernel.org Cc: akpm@linux-foundation.org, bhe@redhat.com, rppt@kernel.org, pasha.tatashin@soleen.com, pratyush@kernel.org, ruirui.yang@linux.dev, corbet@lwn.net, skhan@linuxfoundation.org, catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org, kernel@xen0n.name, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, robh@kernel.org, saravanak@kernel.org, chenwandun@lixiang.com, zhaomeijing@lixiang.com, everyzhao@126.com Subject: [PATCH 06/11] of: reserved_mem: save /memreserve/ entries into reserved_mem array Date: Wed, 29 Apr 2026 14:58:26 +0800 Message-ID: <20260429065831.1510858-7-chenwandun@lixiang.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260429065831.1510858-1-chenwandun@lixiang.com> References: <20260429065831.1510858-1-chenwandun@lixiang.com> Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Save /memreserve/ entries from the FDT header into the reserved_mem array so they can be consumed as vmcore filtering metadata by kdump. /memreserve/ regions hold firmware or bootloader state that is not useful for kernel crash analysis, so saved /memreserve/ entries default to no_dump=true and are tagged with name="memreserve" so consumers can distinguish them from /reserved-memory/ child nodes. Some DTBs declare the same or overlapping range in both /memreserve/ and a /reserved-memory/ child. Commit b41328187629 ("of: fdt: Scan /memreserve/ last") describes one such case on Khadas Vim3 where the range is in /memreserve/ and also in a /reserved-memory/ child carrying no-map. The /reserved-memory/ node's attributes (no-map, reusable, linux,no-dump) are the explicit declaration and must win over the firmware default, fdt_reserved_mem_save_memreserve() therefore inherits no_dump from the overlapping /reserved-memory/ entry rather than silently applying no_dump=true. Signed-off-by: Chen Wandun Tested-by: Zhao Meijing --- drivers/of/of_reserved_mem.c | 107 +++++++++++++++++++++++++++++------ 1 file changed, 91 insertions(+), 16 deletions(-) diff --git a/drivers/of/of_reserved_mem.c b/drivers/of/of_reserved_mem.c index ac3d8b837d61..4b80420da2d2 100644 --- a/drivers/of/of_reserved_mem.c +++ b/drivers/of/of_reserved_mem.c @@ -252,6 +252,49 @@ static void __init __rmem_check_for_overlap(void) } } +/** + * fdt_reserved_mem_save_memreserve() - save a /memreserve/ entry + * @base: base address + * @size: size + * + * Save a /memreserve/ range into reserved_mem[] with no_dump=true + * as the firmware default. If the range overlaps a /reserved-memory/ + * child already saved in this pass, inherit that entry's no_dump so + * node-level attributes (no-map, reusable, linux,no-dump) win over + * the firmware default. + */ +static void __init fdt_reserved_mem_save_memreserve(phys_addr_t base, + phys_addr_t size) +{ + struct reserved_mem *rmem; + phys_addr_t end = base + size; + bool no_dump = true; + int i; + + for (i = 0; i < reserved_mem_count; i++) { + phys_addr_t r_base = reserved_mem[i].base; + phys_addr_t r_end = r_base + reserved_mem[i].size; + + if (base < r_end && end > r_base) { + no_dump = reserved_mem[i].no_dump; + break; + } + } + + if (reserved_mem_count == total_reserved_mem_cnt) { + pr_err("not enough space for all defined regions.\n"); + return; + } + + rmem = &reserved_mem[reserved_mem_count]; + rmem->name = "memreserve"; + rmem->base = base; + rmem->size = size; + rmem->no_dump = no_dump; + + reserved_mem_count++; +} + /** * fdt_scan_reserved_mem_late() - Scan FDT and initialize remaining reserved * memory regions. @@ -260,6 +303,9 @@ static void __init __rmem_check_for_overlap(void) * "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. + * + * In addition, /memreserve/ entries from the FDT header are saved into + * the reserved_mem array so they can be consumed as vmcore metadata. */ void __init fdt_scan_reserved_mem_late(void) { @@ -270,28 +316,32 @@ void __init fdt_scan_reserved_mem_late(void) if (!fdt) return; + /* + * fdt_scan_reserved_mem() has set total_reserved_mem_cnt to the + * total number of entries to be saved (reg-based + /memreserve/). + * If it is zero there is nothing to allocate, save or check. + */ + if (!total_reserved_mem_cnt) + return; + + /* + * Allocate up front: /memreserve/ saves below may run on any + * path and must write into a memblock-backed array, not the + * __initdata reserved_mem_array which is freed at free_initmem(). + */ + alloc_reserved_mem_array(); + node = fdt_path_offset(fdt, "/reserved-memory"); if (node < 0) { pr_info("Reserved memory: No reserved-memory node in the DT\n"); - return; + goto memreserve; } if (__reserved_mem_check_root(node)) { pr_err("Reserved memory: unsupported node format, ignoring\n"); - return; + goto memreserve; } - /* - * fdt_scan_reserved_mem() sets total_reserved_mem_cnt to the - * number of entries that need a slot in reserved_mem[]. If it is - * zero there is nothing to allocate or save. - */ - if (!total_reserved_mem_cnt) - return; - - /* Attempt dynamic allocation of a new reserved_mem array */ - alloc_reserved_mem_array(); - fdt_for_each_subnode(child, fdt, node) { const char *uname; int i, len; @@ -342,6 +392,18 @@ void __init fdt_scan_reserved_mem_late(void) /* check for overlapping reserved regions */ __rmem_check_for_overlap(); + +memreserve: + /* Save /memreserve/ entries (independent of /reserved-memory) */ + for (int i = 0; ; i++) { + u64 mbase, msize; + + if (fdt_get_mem_rsv(fdt, i, &mbase, &msize)) + break; + if (!msize) + break; + fdt_reserved_mem_save_memreserve(mbase, msize); + } } static int __init __reserved_mem_alloc_size(unsigned long node, const char *uname); @@ -365,11 +427,11 @@ int __init fdt_scan_reserved_mem(void) node = fdt_path_offset(fdt, "/reserved-memory"); if (node < 0) - return -ENODEV; + goto memreserve; if (__reserved_mem_check_root(node) != 0) { pr_err("Reserved memory: unsupported node format, ignoring\n"); - return -EINVAL; + goto memreserve; } fdt_for_each_subnode(child, fdt, node) { @@ -406,8 +468,21 @@ int __init fdt_scan_reserved_mem(void) if (!err) count++; } + +memreserve: + /* Count /memreserve/ entries (independent of /reserved-memory) */ + for (int i = 0; ; i++) { + u64 base, size; + + if (fdt_get_mem_rsv(fdt, i, &base, &size)) + break; + if (!size) + break; + count++; + } + total_reserved_mem_cnt = count; - return 0; + return count ? 0 : -ENODEV; } /* -- 2.43.0