Comment 2 for bug 1891288

5.8 kernel running on a QEMU KVM Virtual Machine, arm64, gcov enabled:

CONFIG_GCOV_KERNEL=y
CONFIG_ARCH_HAS_GCOV_PROFILE_ALL=y
CONFIG_GCOV_PROFILE_ALL=y

running: sudo lcov --zerocounters

..causes the following splat:

[ 78.634926] Unable to handle kernel write to read-only memory at virtual address ffffd764f255bb10
[ 78.639076] Mem abort info:
[ 78.640313] ESR = 0x9600004e
[ 78.641656] EC = 0x25: DABT (current EL), IL = 32 bits
[ 78.644351] SET = 0, FnV = 0
[ 78.645766] EA = 0, S1PTW = 0
[ 78.649526] Data abort info:
[ 78.654341] ISV = 0, ISS = 0x0000004e
[ 78.656851] CM = 0, WnR = 1
[ 78.659043] swapper pgtable: 4k pages, 48-bit VAs, pgdp=00000000b775f000
[ 78.665822] [ffffd764f255bb10] pgd=00000001b6fff003, p4d=00000001b6fff003, pud=00000001b6ffe003, pmd=00400000b5000f91
[ 78.677367] Internal error: Oops: 9600004e [#1] SMP
[ 78.681204] Modules linked in: nls_iso8859_1 dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua efi_pstore qemu_fw_cfg sch_fq_codel drm virtio_rng ip_t
ables x_tables autofs4 btrfs blake2b_generic raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor xor_neon raid6_pq libcrc32c rai
d1 raid0 multipath linear crct10dif_ce ghash_ce sha2_ce sha256_arm64 sha1_ce virtio_net xhci_pci net_failover virtio_blk virtio_scsi failover xhci_pci_ren
esas aes_neon_bs aes_neon_blk aes_ce_blk crypto_simd cryptd aes_ce_cipher
[ 78.722642] CPU: 14 PID: 1175 Comm: lcov Tainted: G W 5.8.0-8-generic #9
[ 78.729364] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
[ 78.733467] pstate: 20400005 (nzCv daif +PAN -UAO BTYPE=--)
[ 78.736219] pc : __memset+0x148/0x188
[ 78.737993] lr : gcov_info_reset+0xa0/0x110
[ 78.740037] sp : ffff800010e53bf0
[ 78.741624] x29: ffff800010e53bf0 x28: ffff00015a648000
[ 78.744181] x27: 0000000000000000 x26: ffffd764e3df4060
[ 78.746776] x25: 0000000000000001 x24: ffffd764e3df4040
[ 78.749310] x23: 0000000000000000 x22: ffffd764e3df40a8
[ 78.751976] x21: ffffd764f6295db8 x20: ffffd764e3df4068
[ 78.754642] x19: ffffd764e3df4068 x18: 0000000000000000
[ 78.757265] x17: 0000000000000000 x16: 0000000000000000
[ 78.759922] x15: 0000000000000000 x14: 0000000000000000
[ 78.762585] x13: 0000000000000000 x12: 0000000000000000
[ 78.765209] x11: 0000000000000000 x10: 0000000000000000
[ 78.767861] x9 : 0000000000000000 x8 : ffffd764f255bb10
[ 78.770518] x7 : 0000000000000000 x6 : 000000000000003f
[ 78.773135] x5 : 0000000000000040 x4 : 0000000000000030
[ 78.775793] x3 : 000000071ef97fd0 x2 : 000000071ef97fd0
[ 78.778449] x1 : 0000000000000000 x0 : ffffd764f255bb10
[ 78.781075] Call trace:
[ 78.782329] __memset+0x148/0x188
[ 78.783980] reset_node+0x70/0xc0
[ 78.785628] reset_write+0xc0/0x130
[ 78.787397] full_proxy_write+0x98/0x110
[ 78.789354] vfs_write+0x18c/0x3e0
[ 78.791086] ksys_write+0xc4/0x1f0
[ 78.792778] __arm64_sys_write+0x44/0x60
[ 78.794771] invoke_syscall+0x74/0x150
[ 78.796639] el0_svc_common.constprop.0+0x94/0x264
[ 78.799049] do_el0_svc+0x5c/0x7c
[ 78.800702] el0_svc+0x70/0x114
[ 78.802311] el0_sync_handler+0x140/0x39c
[ 78.804304] el0_sync+0x17c/0x180
[ 78.805967] Code: f101007f fa45a068 54fffc0b aa0303e2 (a9001d07)
[ 78.809019] ---[ end trace b9a826b707c133e4 ]---