From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2D446C433EF for ; Wed, 15 Sep 2021 13:20:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1727B6121F for ; Wed, 15 Sep 2021 13:20:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237413AbhIONVs (ORCPT ); Wed, 15 Sep 2021 09:21:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43696 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234801AbhIONVm (ORCPT ); Wed, 15 Sep 2021 09:21:42 -0400 Received: from albert.telenet-ops.be (albert.telenet-ops.be [IPv6:2a02:1800:110:4::f00:1a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7FC21C061575 for ; Wed, 15 Sep 2021 06:20:23 -0700 (PDT) Received: from ramsan.of.borg ([84.195.186.194]) by albert.telenet-ops.be with bizsmtp id uDLH2500r4C55Sk06DLHoV; Wed, 15 Sep 2021 15:20:21 +0200 Received: from rox.of.borg ([192.168.97.57]) by ramsan.of.borg with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1mQUnf-004eT9-Vh; Wed, 15 Sep 2021 15:18:07 +0200 Received: from geert by rox.of.borg with local (Exim 4.93) (envelope-from ) id 1mQUIy-002gEP-Jn; Wed, 15 Sep 2021 14:46:24 +0200 From: Geert Uytterhoeven To: Russell King , Nicolas Pitre , Ard Biesheuvel , Linus Walleij , Lukasz Stelmach Cc: Simon Horman , linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, Geert Uytterhoeven Subject: [PATCH v6] ARM: uncompress: Parse "linux,usable-memory-range" DT property Date: Wed, 15 Sep 2021 14:46:20 +0200 Message-Id: <0de07021e49ac26a8f9386f62f3e15e947d0f6d0.1631709384.git.geert+renesas@glider.be> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add support for parsing the "linux,usable-memory-range" DT property. This property is used to describe the usable memory reserved for the crash dump kernel, and thus makes the memory reservation explicit. If present, Linux no longer needs to mask the program counter, and rely on the "mem=" kernel parameter to obtain the start and size of usable memory. For backwards compatibility, the traditional method to derive the start of memory is still used if "linux,usable-memory-range" is absent. Signed-off-by: Geert Uytterhoeven --- KernelVersion: v5.15-rc1 --- The corresponding patch for kexec-tools is "[PATCH] arm: kdump: Add DT properties to crash dump kernel's DTB", which is still valid: https://lore.kernel.org/r/20200902154129.6358-1-geert+renesas@glider.be/ v6: - All dependencies are in v5.15-rc1, v5: - Remove the addition of "linux,elfcorehdr" and "linux,usable-memory-range" handling to arch/arm/mm/init.c, v4: - Remove references to architectures in chosen.txt, to avoid having to change this again when more architectures copy kdump support, - Remove the architecture-specific code for parsing "linux,usable-memory-range" and "linux,elfcorehdr", as the FDT core code now takes care of this, - Move chosen.txt change to patch changing the FDT core, - Use IS_ENABLED(CONFIG_CRASH_DUMP) instead of #ifdef, v3: - Rebase on top of accepted solution for DTB memory information handling, which is part of v5.12-rc1, v2: - Rebase on top of reworked DTB memory information handling. --- .../arm/boot/compressed/fdt_check_mem_start.c | 48 ++++++++++++++++--- 1 file changed, 42 insertions(+), 6 deletions(-) diff --git a/arch/arm/boot/compressed/fdt_check_mem_start.c b/arch/arm/boot/compressed/fdt_check_mem_start.c index 62450d824c3ca180..9291a2661bdfe57f 100644 --- a/arch/arm/boot/compressed/fdt_check_mem_start.c +++ b/arch/arm/boot/compressed/fdt_check_mem_start.c @@ -55,16 +55,17 @@ static uint64_t get_val(const fdt32_t *cells, uint32_t ncells) * DTB, and, if out-of-range, replace it by the real start address. * To preserve backwards compatibility (systems reserving a block of memory * at the start of physical memory, kdump, ...), the traditional method is - * always used if it yields a valid address. + * used if it yields a valid address, unless the "linux,usable-memory-range" + * property is present. * * Return value: start address of physical memory to use */ uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt) { - uint32_t addr_cells, size_cells, base; + uint32_t addr_cells, size_cells, usable_base, base; uint32_t fdt_mem_start = 0xffffffff; - const fdt32_t *reg, *endp; - uint64_t size, end; + const fdt32_t *usable, *reg, *endp; + uint64_t size, usable_end, end; const char *type; int offset, len; @@ -80,6 +81,27 @@ uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt) if (addr_cells > 2 || size_cells > 2) return mem_start; + /* + * Usable memory in case of a crash dump kernel + * This property describes a limitation: memory within this range is + * only valid when also described through another mechanism + */ + usable = get_prop(fdt, "/chosen", "linux,usable-memory-range", + (addr_cells + size_cells) * sizeof(fdt32_t)); + if (usable) { + size = get_val(usable + addr_cells, size_cells); + if (!size) + return mem_start; + + if (addr_cells > 1 && fdt32_ld(usable)) { + /* Outside 32-bit address space */ + return mem_start; + } + + usable_base = fdt32_ld(usable + addr_cells - 1); + usable_end = usable_base + size; + } + /* Walk all memory nodes and regions */ for (offset = fdt_next_node(fdt, -1, NULL); offset >= 0; offset = fdt_next_node(fdt, offset, NULL)) { @@ -107,7 +129,20 @@ uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt) base = fdt32_ld(reg + addr_cells - 1); end = base + size; - if (mem_start >= base && mem_start < end) { + if (usable) { + /* + * Clip to usable range, which takes precedence + * over mem_start + */ + if (base < usable_base) + base = usable_base; + + if (end > usable_end) + end = usable_end; + + if (end <= base) + continue; + } else if (mem_start >= base && mem_start < end) { /* Calculated address is valid, use it */ return mem_start; } @@ -123,7 +158,8 @@ uint32_t fdt_check_mem_start(uint32_t mem_start, const void *fdt) } /* - * The calculated address is not usable. + * The calculated address is not usable, or was overridden by the + * "linux,usable-memory-range" property. * Use the lowest usable physical memory address from the DTB instead, * and make sure this is a multiple of 2 MiB for phys/virt patching. */ -- 2.25.1