nios2 crash due to 'init/main.c: extract early boot entropy from the passed cmdline'

[Guenter Roeck]

Hi,

I noticed that nios2 images crash in mainline. Bisect points to commit
33d72f3822d7 ("init/main.c: extract early boot entropy from the passed
cmdline").  Bisect log is attached.

As far as I can see, the problem is seen because add_device_randomness()
calls random_get_entropy(). However, the underlying timer function
used by the nios2 architecture (nios2_timer_read) is not yet initialized,
causing a NULL pointer access and crash. A sample crash log is at
	http://kerneltests.org/builders/qemu-nios2-master/builds/175/steps/qemubuildcommand/logs/stdio

Guenter

---
# bad: [4dfc2788033d30dfccfd4268e06dd73ce2c654ed] Merge tag 'iommu-updates-v4.14' of git://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu
# good: [5969d1bb3082b41eba8fd2c826559abe38ccb6df] Merge branch 'gperf-removal'
git bisect start 'HEAD' '5969d1bb3082'
# bad: [fbd01410e89a66f346ba1b3c0161e1198449b746] Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
git bisect bad fbd01410e89a66f346ba1b3c0161e1198449b746
# good: [0d519f2d1ed1f11e49abc88cfcf6cf13b83ba14c] Merge tag 'pci-v4.14-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci
git bisect good 0d519f2d1ed1f11e49abc88cfcf6cf13b83ba14c
# bad: [229cf16d3c8ac2e9b082c223fd0e619dc8f62cc1] sh: defconfig: cleanup from old Kconfig options
git bisect bad 229cf16d3c8ac2e9b082c223fd0e619dc8f62cc1
# good: [1caffba9db4aa27c3e7ebc05668afca1f991ab8d] drivers/scsi/sym53c8xx_2/sym_hipd.c: convert to use memset32
git bisect good 1caffba9db4aa27c3e7ebc05668afca1f991ab8d
# good: [7c61bd6983b185272315722787cceacf5f5d2e7d] lib/cmdline.c: remove meaningless comment
git bisect good 7c61bd6983b185272315722787cceacf5f5d2e7d
# bad: [718b303b49893d8f9dd469f710d76f77673bd35d] autofs: use AUTOFS_DEV_IOCTL_SIZE
git bisect bad 718b303b49893d8f9dd469f710d76f77673bd35d
# good: [9367bb730e4d9d85a8911a08a3542ec2aa873d37] binfmt_flat: delete two error messages for a failed memory allocation in decompress_exec()
git bisect good 9367bb730e4d9d85a8911a08a3542ec2aa873d37
# bad: [e54c7bcbf14a25dc3a913b4c808b52121c522e9b] autofs: make disc device user accessible
git bisect bad e54c7bcbf14a25dc3a913b4c808b52121c522e9b
# bad: [33d72f3822d7ff8a9e45bd7413c811085cb87aa5] init/main.c: extract early boot entropy from the passed cmdline
git bisect bad 33d72f3822d7ff8a9e45bd7413c811085cb87aa5
# good: [121388a31362b0d3176dc1190ac8064b98a61b20] init: move stack canary initialization after setup_arch
git bisect good 121388a31362b0d3176dc1190ac8064b98a61b20
# first bad commit: [33d72f3822d7ff8a9e45bd7413c811085cb87aa5] init/main.c: extract early boot entropy from the passed cmdline