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[209.6.122.159]) by smtp.gmail.com with ESMTPSA id l34sm2437104qtd.71.2019.12.03.12.14.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Dec 2019 12:14:41 -0800 (PST) From: Masayoshi Mizuma To: Ard Biesheuvel , linux-arm-kernel@lists.infradead.org, linux-efi@vger.kernel.org Cc: Masayoshi Mizuma , Masayoshi Mizuma , linux-kernel@vger.kernel.org, kexec@lists.infradead.org, d.hatayama@fujitsu.com, Eric Biederman , Matthias Brugger Subject: [PATCH v2 2/2] efi: arm64: Introduce /proc/efi/memreserve to tell the persistent pages Date: Tue, 3 Dec 2019 15:14:10 -0500 Message-Id: <20191203201410.28045-3-msys.mizuma@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20191203201410.28045-1-msys.mizuma@gmail.com> References: <20191203201410.28045-1-msys.mizuma@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.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 /proc/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 | 75 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 72 insertions(+), 3 deletions(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index d8157cb34..80bbe0b3e 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -325,17 +325,87 @@ static __init int efivar_ssdt_load(void) static inline int efivar_ssdt_load(void) { return 0; } #endif +static struct linux_efi_memreserve *efi_memreserve_root __ro_after_init; + #ifdef CONFIG_PROC_FS static struct proc_dir_entry *proc_efi; +#ifdef CONFIG_KEXEC +static int memreserve_show(struct seq_file *m, void *v) +{ + struct linux_efi_memreserve *rsv; + phys_addr_t start, end; + unsigned long prsv; + int count, i; + + 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; + + seq_printf(m, "%pa-%pa\n", &start, &end); + } + memunmap(rsv); + } + + return 0; +} + +static int memreserve_open(struct inode *inode, struct file *filp) +{ + return single_open(filp, memreserve_show, NULL); +} + +static const struct file_operations memreserve_fops = { + .owner = THIS_MODULE, + .open = memreserve_open, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +static int __init efi_proc_memreserve(void) +{ + struct proc_dir_entry *pde; + + if ((efi_memreserve_root == (void *)ULONG_MAX) || + (!efi_memreserve_root)) + return 0; + + pde = proc_create("memreserve", 0444, proc_efi, &memreserve_fops); + if (!pde) { + pr_err("/proc/efi: Cannot create /proc/efi/memreserve file.\n"); + return 1; + } + + return 0; +} +#else +static inline int efi_proc_memreserve(void) { return 0; } +#endif /* CONFIG_KEXEC */ + static int __init efi_proc_init(void) { + int error = 1; + proc_efi = proc_mkdir("efi", NULL); if (!proc_efi) { pr_err("/proc/efi: Cannot create /proc/efi directroy.\n"); - return 1; + return error; } - return 0; + error = efi_proc_memreserve(); + + return error; } #else static inline int efi_proc_init(void) { return 0; } @@ -986,7 +1056,6 @@ 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) { -- 2.18.1