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[209.6.122.159]) by smtp.gmail.com with ESMTPSA id x65sm9461856qkd.15.2019.11.12.08.53.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 12 Nov 2019 08:53:54 -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 Subject: [RFC PATCH] efi: arm64: Introduce /sys/firmware/efi/memreserve to tell the persistent pages Date: Tue, 12 Nov 2019 11:53:03 -0500 Message-Id: <20191112165303.24270-1-msys.mizuma@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org From: Masayoshi Mizuma kexec reboot stucks because efi_config_parse_tables() refers garbage (with memblock=debug): 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 pending table and prop table which are allocated by gic_reserve_range(). The destroyer is kexec. kexec locates the inird 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: 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 appropriate 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 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 | 32 +++++++++++++++++++++++++++++++- 1 file changed, 31 insertions(+), 1 deletion(-) diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index e98bbf8e5..67b21ae7a 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -141,6 +141,36 @@ 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; + unsigned long prsv; + char *str = buf; + int index, i; + + if (!kobj || !buf) + return -EINVAL; + + if (!efi_memreserve_root) + return -ENODEV; + + for (prsv = efi_memreserve_root->next; prsv; prsv = rsv->next) { + rsv = memremap(prsv, sizeof(*rsv), MEMREMAP_WB); + index = atomic_read(&rsv->count); + for (i = 0; i < index; i++) + str += sprintf(str, "%llx-%llx\n", + rsv->entry[i].base, + rsv->entry[i].base + rsv->entry[i].size - 1); + 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) \ @@ -172,6 +202,7 @@ 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, }; @@ -955,7 +986,6 @@ 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