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[66.187.233.206]) by smtp.gmail.com with ESMTPSA id f191sm1419361qke.62.2019.11.13.11.43.23 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 13 Nov 2019 11:43:23 -0800 (PST) Date: Wed, 13 Nov 2019 14:43:16 -0500 From: Masayoshi Mizuma To: "d.hatayama@fujitsu.com" Cc: Ard Biesheuvel , "linux-arm-kernel@lists.infradead.org" , "linux-efi@vger.kernel.org" , "m.mizuma@jp.fujitsu.com" , "linux-kernel@vger.kernel.org" , "kexec@lists.infradead.org" Subject: Re: [RFC PATCH] efi: arm64: Introduce /sys/firmware/efi/memreserve to tell the persistent pages Message-ID: <20191113194229.jfaawdhummneri6s@gabell> References: <20191112165303.24270-1-msys.mizuma@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180716 Sender: linux-efi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-efi@vger.kernel.org On Wed, Nov 13, 2019 at 07:59:04AM +0000, d.hatayama@fujitsu.com wrote: > > 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; > > Other functions use different conditions. > The latter efi_memreserve_root == (void *)ULONG_MAX is correct? > > static int __init efi_memreserve_map_root(void) > { > if (efi.mem_reserve == EFI_INVALID_TABLE_ADDR) > return -ENODEV; > int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size) > { > struct linux_efi_memreserve *rsv; > unsigned long prsv; > int rc, index; > > if (efi_memreserve_root == (void *)ULONG_MAX) > return -ENODEV; I think it's better to add both checks like as: 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); > > memremap() could fail with NULL as a return value. > You need to deal with such case. > > It looks to me efi_mem_reserve_persistent() also doesn't deal with this. > Maybe you should fix this, too. OK, I'll post a patch sepaletely to add the sanity check. > > > + 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); > > Is memreserve supported on 32-bit system? > If so, phy_addr_t could have a type of 4-byte length in such system > (not so if with PAE) and then %llx could lead to inconsistent type error. > It's enough to add a cast to unsigned long long. Good catch. I'll modify the sprintf() format to use %pa like as: phys_addr_t start, end; for (i = 0; i < index; i++) { start = rsv->entry[i].base; end = start + rsv->entry[i].size - 1; str += sprintf(str, "%pa-%pa\n", &start, &end); } Thanks, Masa > > > + 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 >