riscv: cacheinfo: Fix using smp_processor_id() in preemptible

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>

diff --git a/arch/riscv/kernel/cacheinfo.c b/arch/riscv/kernel/cacheinfo.c
index de59dd457b41584083dee7866e189bbb396945dd..d8678135704425973c3ba11d058dd56babef2481 100644 (file)
--- 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;