> -----Original Message----- > From: linux-kernel-owner@xxxxxxxxxxxxxxx > [mailto:linux-kernel-owner@xxxxxxxxxxxxxxx] On Behalf Of Masayoshi Mizuma > Sent: Wednesday, November 13, 2019 1:53 AM > To: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>; > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-efi@xxxxxxxxxxxxxxx > Cc: Masayoshi Mizuma <msys.mizuma@xxxxxxxxx>; Mizuma, Masayoshi/水間 理仁 > <m.mizuma@xxxxxxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx; > kexec@xxxxxxxxxxxxxxxxxxx > Subject: [RFC PATCH] efi: arm64: Introduce /sys/firmware/efi/memreserve to > tell the persistent pages > > From: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx> > > 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 <m.mizuma@xxxxxxxxxxxxxx> > --- > 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; > + > + 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. > + 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. > + 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
