| From 3370e13aa463adb84488ebf0e599e3dc0024315b Mon Sep 17 00:00:00 2001 |
| From: Sudeep Holla <sudeep.holla@arm.com> |
| Date: Wed, 27 May 2015 11:26:13 +0100 |
| Subject: drivers/base: cacheinfo: handle absence of caches |
| |
| From: Sudeep Holla <sudeep.holla@arm.com> |
| |
| commit 3370e13aa463adb84488ebf0e599e3dc0024315b upstream. |
| |
| On some simulators like GEM5, caches may not be simulated. In those |
| cases, the cache levels and leaves will be zero and will result in |
| following exception: |
| |
| Unable to handle kernel NULL pointer dereference at virtual address 0040 |
| pgd = ffffffc0008fa000 |
| [00000040] *pgd=00000009f6807003, *pud=00000009f6807003, |
| *pmd=00000009f6808003, *pte=006000002c010707 |
| Internal error: Oops: 96000005 [#1] PREEMPT SMP |
| Modules linked in: |
| CPU: 1 PID: 1 Comm: swapper/0 Not tainted 4.1.0-rc5 #198 |
| task: ffffffc9768a0000 ti: ffffffc9768a8000 task.ti: ffffffc9768a8000 |
| PC is at detect_cache_attributes+0x98/0x2c8 |
| LR is at detect_cache_attributes+0x88/0x2c8 |
| |
| kcalloc(0) returns a special value ZERO_SIZE_PTR which is non-NULL value |
| but results in fault only on any attempt to dereferencing it. So |
| checking for the non-NULL pointer will not suffice. |
| |
| This patch checks for non-zero cache leaf nodes and returns error if |
| there are no cache leaves in detect_cache_attributes. |
| |
| Cc: Will Deacon <will.deacon@arm.com> |
| Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Reported-by: William Wang <william.wang@arm.com> |
| Signed-off-by: Sudeep Holla <sudeep.holla@arm.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| drivers/base/cacheinfo.c | 2 +- |
| 1 file changed, 1 insertion(+), 1 deletion(-) |
| |
| --- a/drivers/base/cacheinfo.c |
| +++ b/drivers/base/cacheinfo.c |
| @@ -179,7 +179,7 @@ static int detect_cache_attributes(unsig |
| { |
| int ret; |
| |
| - if (init_cache_level(cpu)) |
| + if (init_cache_level(cpu) || !cache_leaves(cpu)) |
| return -ENOENT; |
| |
| per_cpu_cacheinfo(cpu) = kcalloc(cache_leaves(cpu), |