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[66.187.233.206]) by smtp.gmail.com with ESMTPSA id n20sm2767705qkn.118.2019.11.14.08.11.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 14 Nov 2019 08:11:17 -0800 (PST) From: Masayoshi Mizuma To: Ard Biesheuvel , linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org Subject: [RFC PATCH v2] efi: arm64: Introduce /sys/firmware/efi/memreserve to tell the persistent pages Date: Thu, 14 Nov 2019 11:10:19 -0500 Message-Id: <20191114161019.8735-1-msys.mizuma@gmail.com> X-Mailer: git-send-email 2.17.1 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20191114_081120_966470_BAA697A7 X-CRM114-Status: GOOD ( 11.60 ) X-Spam-Score: -0.2 (/) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-0.2 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at https://www.dnswl.org/, no trust [2607:f8b0:4864:20:0:0:0:843 listed in] [list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (msys.mizuma[at]gmail.com) 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Masayoshi Mizuma , Masayoshi Mizuma , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, d.hatayama@fujitsu.com MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org From: Masayoshi Mizuma kexec reboot stops in early boot sequence because efi_config_parse_tables() refers garbage data. We can see the log with memblock=debug kernel option: efi: ACPI 2.0=0x9821790014 PROP=0x8757f5c0 SMBIOS 3.0=0x9820740000 MEMRESERVE=0x9820bfdc58 memblock_reserve: [0x0000009820bfdc58-0x0000009820bfdc67] efi_config_parse_tables+0x228/0x278 memblock_reserve: [0x0000000082760000-0x00000000324d07ff] efi_config_parse_tables+0x228/0x278 memblock_reserve: [0xcc4f84ecc0511670-0x5f6e5214a7fd91f9] efi_config_parse_tables+0x244/0x278 memblock_reserve: [0xd2fd4144b9af693d-0xad0c1db1086f40a2] efi_config_parse_tables+0x244/0x278 memblock_reserve: [0x0c719bb159b1fadc-0x5aa6e62a1417ce12] efi_config_parse_tables+0x244/0x278 ... That happens because 0x82760000, struct linux_efi_memreserve, is destroyed. 0x82760000 is pointed from efi.mem_reseve, and efi.mem_reserve points the head page of LPI pending table and LPI property table which are allocated by gic_reserve_range(). The destroyer is kexec. kexec locates the initrd to the area: ]# kexec -d -l /boot/vmlinuz-5.4.0-rc7 /boot/initramfs-5.4.0-rc7.img --reuse-cmdline ... initrd: base 82290000, size 388dd8ah (59301258) ... From dynamic debug log. initrd is located in segment[1]: machine_kexec_prepare:70: kexec kimage info: type: 0 start: 85b30680 head: 0 nr_segments: 4 segment[0]: 0000000080480000 - 0000000082290000, 0x1e10000 bytes, 481 pages segment[1]: 0000000082290000 - 0000000085b20000, 0x3890000 bytes, 905 pages segment[2]: 0000000085b20000 - 0000000085b30000, 0x10000 bytes, 1 pages segment[3]: 0000000085b30000 - 0000000085b40000, 0x10000 bytes, 1 pages kexec searches the memory region to locate initrd through "System RAM" in /proc/iomem. The pending tables are included in "System RAM" because they are allocated by alloc_pages(), so kexec destroys the LPI pending tables. Introduce /sys/firmware/efi/memreserve to tell the pages pointed by efi.mem_reserve so that kexec can avoid the area to locate initrd. Signed-off-by: Masayoshi Mizuma --- drivers/firmware/efi/efi.c | 41 +++++++++++++++++++++++++++++++++++++- 1 file changed, 40 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 0b6b0c19a..07812d697 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -149,6 +149,45 @@ static ssize_t systab_show(struct kobject *kobj, static struct kobj_attribute efi_attr_systab = __ATTR_RO_MODE(systab, 0400); +static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init; +static ssize_t memreserve_show(struct kobject *kobj, + struct kobj_attribute *attr, char *buf) +{ + struct linux_efi_memreserve *rsv; + phys_addr_t start, end; + unsigned long prsv; + char *str = buf; + int count, i; + + if (!kobj || !buf) + return -EINVAL; + + if ((efi_memreserve_root == (void *)ULONG_MAX) || + (!efi_memreserve_root)) + return -ENODEV; + + for (prsv = efi_memreserve_root->next; prsv; prsv = rsv->next) { + rsv = memremap(prsv, sizeof(*rsv), MEMREMAP_WB); + if (!rsv) { + pr_err("Could not map efi_memreserve\n"); + return -ENOMEM; + } + count = atomic_read(&rsv->count); + for (i = 0; i < count; i++) { + start = rsv->entry[i].base; + end = start + rsv->entry[i].size - 1; + + str += sprintf(str, "%pa-%pa\n", &start, &end); + } + memunmap(rsv); + } + + return str - buf; +} + +static struct kobj_attribute efi_attr_memreserve = + __ATTR_RO_MODE(memreserve, 0444); + #define EFI_FIELD(var) efi.var #define EFI_ATTR_SHOW(name) \ @@ -180,6 +219,7 @@ static struct attribute *efi_subsys_attrs[] = { &efi_attr_runtime.attr, &efi_attr_config_table.attr, &efi_attr_fw_platform_size.attr, + &efi_attr_memreserve.attr, NULL, }; @@ -964,7 +1004,6 @@ int efi_status_to_err(efi_status_t status) } static DEFINE_SPINLOCK(efi_mem_reserve_persistent_lock); -static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init; static int __init efi_memreserve_map_root(void) {