[PATCH AUTOSEL 5.10 22/45] riscv: cacheinfo: Fix using smp_processor_id() in preemptible

Sasha Levin
2021-01-20T02:35:36Z

From: Kefeng Wang <wangkefeng.wang@huawei.com>

[ Upstream commit 80709af7325d179b433817f421c85449f2454046 ]

Use raw_smp_processor_id instead of smp_processor_id() to fix warning,

BUG: using smp_processor_id() in preemptible [00000000] code: init/1
caller is debug_smp_processor_id+0x1c/0x26
CPU: 0 PID: 1 Comm: init Not tainted 5.10.0-rc4 #211
Call Trace:
walk_stackframe+0x0/0xaa
show_stack+0x32/0x3e
dump_stack+0x76/0x90
check_preemption_disabled+0xaa/0xac
debug_smp_processor_id+0x1c/0x26
get_cache_size+0x18/0x68
load_elf_binary+0x868/0xece
bprm_execve+0x224/0x498
kernel_execve+0xdc/0x142
run_init_process+0x90/0x9e
try_to_run_init_process+0x12/0x3c
kernel_init+0xb4/0xf8
ret_from_exception+0x0/0xc

The issue is found when CONFIG_DEBUG_PREEMPT enabled.

Reviewed-by: Atish Patra <atish.patra@wdc.com>
Tested-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
[Palmer: Added a comment.]
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/riscv/kernel/cacheinfo.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/cacheinfo.c b/arch/riscv/kernel/cacheinfo.c
index de59dd457b415..d867813570442 100644
--- a/arch/riscv/kernel/cacheinfo.c
+++ b/arch/riscv/kernel/cacheinfo.c
@@ -26,7 +26,16 @@ cache_get_priv_group(struct cacheinfo *this_leaf)

static struct cacheinfo *get_cacheinfo(u32 level, enum cache_type type)
{
- struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(smp_processor_id());
+ /*
+ * Using raw_smp_processor_id() elides a preemptability check, but this
+ * is really indicative of a larger problem: the cacheinfo UABI assumes
+ * that cores have a homonogenous view of the cache hierarchy. That
+ * happens to be the case for the current set of RISC-V systems, but
+ * likely won't be true in general. Since there's no way to provide
+ * correct information for these systems via the current UABI we're
+ * just eliding the check for now.
+ */
+ struct cpu_cacheinfo *this_cpu_ci = get_cpu_cacheinfo(raw_smp_processor_id());
struct cacheinfo *this_leaf;
int index;

--
2.27.0