[ +ACPI audience ]
On 2021-06-25 12:15, Robin Murphy wrote:
On 2021-06-25 12:09, Catalin Marinas wrote:
On Fri, Jun 25, 2021 at 12:02:52PM +0100, Robin Murphy wrote:
On 2021-06-25 10:52, Veronika Kabatova wrote:
[...]
❌ stress: stress-ng
Oh no, this looks like another alignment fault in memcpy:
[13330.651903] Unable to handle kernel paging request at virtual
address ffff8000534705ff
[13330.651914] Mem abort info:
[13330.651918] ESR = 0x96000021
[13330.651922] EC = 0x25: DABT (current EL), IL = 32 bits
[13330.651928] SET = 0, FnV = 0
[13330.651931] EA = 0, S1PTW = 0
[13330.651933] FSC = 0x21: alignment fault
[13330.651938] Data abort info:
[13330.651940] ISV = 0, ISS = 0x00000021
[13330.651941] CM = 0, WnR = 0
[13330.651943] swapper pgtable: 4k pages, 48-bit VAs,
pgdp=00000000f3e6b000
[13330.651945] [ffff8000534705ff] pgd=1000008ffcfff003,
p4d=1000008ffcfff003, pud=100000088e57d003, pmd=10000008d0aeb003,
pte=006800008021370f
[13330.651956] Internal error: Oops: 96000021 [#1] SMP
[13330.651961] Modules linked in: unix_diag binfmt_misc fcrypt
sm4_generic crc32_generic md4 michael_mic nhpoly1305_neon
nhpoly1305 poly1305_generic libpoly1305 poly1305_neon rmd160
sha3_generic sm3_generic streebog_generic wp512 blowfish_generic
blowfish_common cast5_generic des_generic libdes chacha_generic
chacha_neon libchacha camellia_generic cast6_generic cast_common
serpent_generic twofish_generic twofish_common dm_thin_pool
dm_persistent_data dm_bio_prison nvme nvme_core ipmi_watchdog
ipmi_poweroff loop tun af_key crypto_user scsi_transport_iscsi
xt_multiport ip_gre ip_tunnel gre overlay xt_CONNSECMARK xt_SECMARK
nft_counter xt_state xt_conntrack nft_compat ah6 ah4 nft_objref
nft_ct nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables
nfnetlink jfs sctp ip6_udp_tunnel udp_tunnel dm_log_writes
dm_flakey rfkill mlx5_ib ib_uverbs ib_core sunrpc coresight_etm4x
i2c_smbus coresight_replicator coresight_tpiu coresight_tmc joydev
mlx5_core acpi_ipmi psample ipmi_ssif mlxfw !
ipmi_devintf
[13330.652076] ipmi_msghandler coresight_funnel thunderx2_pmu
coresight vfat fat fuse zram ip_tables xfs ast crct10dif_ce
i2c_algo_bit ghash_ce drm_vram_helper drm_kms_helper syscopyarea
sysfillrect sysimgblt fb_sys_fops cec drm_ttm_helper ttm drm
gpio_xlp i2c_xlp9xx uas usb_storage aes_neon_bs [last unloaded: nvmet]
[13330.652123] CPU: 115 PID: 188446 Comm: stress-ng Tainted:
G OEL 5.13.0-rc7 #1
[13330.652129] Hardware name: HPE Apollo 70
/C01_APACHE_MB , BIOS L50_5.13_1.15 05/08/2020
[13330.652133] pstate: 80400009 (Nzcv daif +PAN -UAO -TCO BTYPE=--)
[13330.652139] pc : __memcpy+0x168/0x250
[13330.652150] lr : memory_read_from_buffer+0x58/0x80
[13330.652161] sp : ffff800063ef3c20
[13330.652163] x29: ffff800063ef3c20 x28: ffff0008b1380000 x27:
0000000000000000
[13330.652170] x26: 0000000000000000 x25: 0000000000000000 x24:
ffff00080a960fe0
[13330.652176] x23: ffff800063ef3d28 x22: 000000000000063f x21:
ffff800063ef3c88
[13330.652181] x20: 000000000000063f x19: 000000000000063f x18:
0000000000000000
[13330.652186] x17: 0000000000000000 x16: 0000000000000000 x15:
0000000000000000
[13330.652191] x14: 0000000000000000 x13: 0000000000000000 x12:
0000000000000000
[13330.652196] x11: 0000000000000000 x10: 0000000000000000 x9 :
0000000000000000
[13330.652200] x8 : 0000000000000000 x7 : 0000000000000000 x6 :
0000000000000000
[13330.652206] x5 : ffff000d0fb0063f x4 : ffff80005347063f x3 :
ffff000d0fb005c0
[13330.652212] x2 : ffffffffffffffef x1 : ffff800053470600 x0 :
ffff000d0fb00000
[13330.652218] Call trace:
[13330.652221] __memcpy+0x168/0x250
[13330.652225] acpi_data_show+0x5c/0x8c
[13330.652232] sysfs_kf_bin_read+0x78/0xa0
[13330.652238] kernfs_file_read_iter+0x9c/0x1a4
[13330.652241] kernfs_fop_read_iter+0x34/0x50
[13330.652244] new_sync_read+0xdc/0x154
[13330.652253] vfs_read+0x158/0x1e4
[13330.652260] ksys_read+0x64/0xec
[13330.652266] __arm64_sys_read+0x28/0x34
[13330.652273] invoke_syscall+0x50/0x120
[13330.652280] el0_svc_common.constprop.0+0x4c/0xd4
[13330.652284] do_el0_svc+0x30/0x9c
[13330.652286] el0_svc+0x2c/0x54
[13330.652294] el0t_64_sync_handler+0x1a4/0x1b0
[13330.652296] el0t_64_sync+0x19c/0x1a0
[13330.652303] Code: a984346c a9c4342c f1010042 54fffee8 (a97c3c8e)
[13330.652307] ---[ end trace 227d4380f57145d4 ]---
So maybe this issue isn't limited to weird modules, after all...
It ran on the machine from the same set that we were able to reproduce
it on previously. If you or anyone else have an idea on how to
stabilize
the reproducibility or have a debug patch we'll be happy to try it.
Possibly it depends on the individual machines' firmware exactly how the
relevant bits of their ACPI tables are aligned in memory?
I've started digging into that callstack - it may not be a "weird
module"
but it's definitely crusty ACPI code... a238317ce818 ("ACPI: Clean up
acpi_os_map/unmap_memory() to eliminate __iomem.") looks frankly a bit
questionable in its decision to blithely cast away __iomem, but then the
rationale in aafc65c731fe ("ACPI: add arm64 to the platforms that use
ioremap") seems particularly dubious on top of that (especially given
this
end result).
At a wild guess, I'm wondering if this may be sufficient:
----->8-----
diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c
index 327e1b4eb6b0..f5d26b102fbe 100644
--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -277,7 +277,7 @@ acpi_map_lookup_virt(void __iomem *virt,
acpi_size size)
return NULL;
}
-#if defined(CONFIG_IA64) || defined(CONFIG_ARM64)
+#if defined(CONFIG_IA64)
/* ioremap will take care of cache attributes */
#define should_use_kmap(pfn) 0
#else
-----8<-----
I thought the same but shouldn't acpi_os_ioremap() map it with the right
attributes? It uses the EFI maps to check what kind of memory this is.
Oh crikey, I missed that branch of the rabbit hole... I guess that must
mean that the tables being poked here are *not* covered by the EFI
memory map, so page_is_ram() is unlikely to help either :(
After picking through the UEFI spec I think I've now got a clearer
picture of what's happening, but I'm not sure where it goes from here...
The spec implies that it *is* legitimate for runtime-loaded ACPI tables
to lie outside the EFI memory map, and that case they must be assumed to
be uncached, so the behaviour of acpi_os_ioremap() is correct. Given the
definition of uncached for arm64 memory types though, that means that
callers of acpi_os_map_memory() still have to be prepared to get an
__iomem pointer back even if they know they're mapping a table rather
than some random bit of MMIO for an AML method.
Therefore in this case it seems the blame lies partway between
acpi_os_map_memory() for casting away __iomem and acpi_data_show() for
letting an arbitrary offset lead to an arbitrarily-aligned memcpy(), but
I don't know what the best way to fix it is. Either way I've satisfied
myself that it's not an issue with the arm64 code itself - I do wonder
whether this might also be a problem on IA-64 given
ACPI_MISALIGNMENT_NOT_SUPPORTED, and I guess RISC-V may have alignment
concerns as well.
Robin.
