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| author | Guenter Roeck <linux@roeck-us.net> | 2017-09-11 20:45:26 -0700 |
|---|---|---|
| committer | Ley Foon Tan <ley.foon.tan@intel.com> | 2017-09-15 20:30:58 +0800 |
| commit | 65d1e3ddeae117f6a224535e10a09145f0f96508 (patch) | |
| tree | 232ed2e3f7fea91bf15a68f40cb131238d39aa8d /arch/nios2 | |
| parent | 8993d5e4662b16845492c413efe82ec162bf5370 (diff) | |
| download | linux-riscv-65d1e3ddeae117f6a224535e10a09145f0f96508.tar.gz linux-riscv-65d1e3ddeae117f6a224535e10a09145f0f96508.tar.bz2 linux-riscv-65d1e3ddeae117f6a224535e10a09145f0f96508.zip | |
nios2: time: Read timer in get_cycles only if initialized
Mainline crashes as follows when running nios2 images.
On node 0 totalpages: 65536
free_area_init_node: node 0, pgdat c8408fa0, node_mem_map c8726000
Normal zone: 512 pages used for memmap
Normal zone: 0 pages reserved
Normal zone: 65536 pages, LIFO batch:15
Unable to handle kernel NULL pointer dereference at virtual address 00000000
ea = c8003cb0, ra = c81cbf40, cause = 15
Kernel panic - not syncing: Oops
Problem is seen because get_cycles() is called before the timer it depends
on is initialized. Returning 0 in that situation fixes the problem.
Fixes: 33d72f3822d7 ("init/main.c: extract early boot entropy from the ..")
Cc: Laura Abbott <labbott@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Diffstat (limited to 'arch/nios2')
| -rw-r--r-- | arch/nios2/kernel/time.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/nios2/kernel/time.c b/arch/nios2/kernel/time.c index 645129aaa9a0..20e86209ef2e 100644 --- a/arch/nios2/kernel/time.c +++ b/arch/nios2/kernel/time.c @@ -107,7 +107,10 @@ static struct nios2_clocksource nios2_cs = { cycles_t get_cycles(void) { - return nios2_timer_read(&nios2_cs.cs); + /* Only read timer if it has been initialized */ + if (nios2_cs.timer.base) + return nios2_timer_read(&nios2_cs.cs); + return 0; } EXPORT_SYMBOL(get_cycles); |