git.openwrt.org Git - openwrt/staging/xback.git/blob

   1 From 1cab5bd69eb1f995ced2d7576cb15f8a8941fd85 Mon Sep 17 00:00:00 2001
   2 From: Tiezhu Yang <yangtiezhu@loongson.cn>
   3 Date: Thu, 25 Nov 2021 19:39:32 +0800
   4 Subject: [PATCH 1/1] MIPS: Fix using smp_processor_id() in preemptible in
   5  show_cpuinfo()
   6
   7 There exists the following issue under DEBUG_PREEMPT:
   8
   9  BUG: using smp_processor_id() in preemptible [00000000] code: systemd/1
  10  caller is show_cpuinfo+0x460/0xea0
  11  ...
  12  Call Trace:
  13  [<ffffffff8020f0dc>] show_stack+0x94/0x128
  14  [<ffffffff80e6cab4>] dump_stack_lvl+0x94/0xd8
  15  [<ffffffff80e74c5c>] check_preemption_disabled+0x104/0x110
  16  [<ffffffff802209c8>] show_cpuinfo+0x460/0xea0
  17  [<ffffffff80539d54>] seq_read_iter+0xfc/0x4f8
  18  [<ffffffff804fcc10>] new_sync_read+0x110/0x1b8
  19  [<ffffffff804ff57c>] vfs_read+0x1b4/0x1d0
  20  [<ffffffff804ffb18>] ksys_read+0xd0/0x110
  21  [<ffffffff8021c090>] syscall_common+0x34/0x58
  22
  23 We can see the following call trace:
  24  show_cpuinfo()
  25    cpu_has_fpu
  26      current_cpu_data
  27        smp_processor_id()
  28
  29  $ addr2line -f -e vmlinux 0xffffffff802209c8
  30  show_cpuinfo
  31  arch/mips/kernel/proc.c:188
  32
  33  $ head -188 arch/mips/kernel/proc.c | tail -1
  34          if (cpu_has_fpu)
  35
  36  arch/mips/include/asm/cpu-features.h
  37  #  define cpu_has_fpu          (current_cpu_data.options & MIPS_CPU_FPU)
  38
  39  arch/mips/include/asm/cpu-info.h
  40  #define current_cpu_data cpu_data[smp_processor_id()]
  41
  42 Based on the above analysis, fix the issue by using raw_cpu_has_fpu
  43 which calls raw_smp_processor_id() in show_cpuinfo().
  44
  45 Fixes: 626bfa037299 ("MIPS: kernel: proc: add CPU option reporting")
  46 Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
  47 Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
  48 ---
  49  arch/mips/kernel/proc.c | 2 +-
  50  1 file changed, 1 insertion(+), 1 deletion(-)
  51
  52 --- a/arch/mips/kernel/proc.c
  53 +++ b/arch/mips/kernel/proc.c
  54 @@ -166,7 +166,7 @@ static int show_cpuinfo(struct seq_file
  55                 seq_puts(m, " tx39_cache");
  56         if (cpu_has_octeon_cache)
  57                 seq_puts(m, " octeon_cache");
  58 -       if (cpu_has_fpu)
  59 +       if (raw_cpu_has_fpu)
  60                 seq_puts(m, " fpu");
  61         if (cpu_has_32fpr)
  62                 seq_puts(m, " 32fpr");