dangling pointer to '__str' error on ppc64_defconfig, GCC 12.1.0

Bagas Sanjaya bagasdotme at gmail.com
Thu May 26 19:17:15 AEST 2022


Hi everyone,

Attempting to build ppc64_defconfig kernel with powerpc64-unknown-linux-gnu
(GCC 12.1.0) on v5.18, I got build error on ftrace.o:

  CC      arch/powerpc/kernel/trace/ftrace.o
  CC      init/init_task.o
In file included from ./include/asm-generic/bug.h:22,
                 from ./arch/powerpc/include/asm/bug.h:156,
                 from ./include/linux/bug.h:5,
                 from ./include/linux/thread_info.h:13,
                 from ./include/asm-generic/preempt.h:5,
                 from ./arch/powerpc/include/generated/asm/preempt.h:1,
                 from ./include/linux/preempt.h:78,
                 from ./include/linux/spinlock.h:55,
                 from arch/powerpc/kernel/trace/ftrace.c:16:
arch/powerpc/kernel/trace/ftrace.c: In function 'ftrace_modify_code':
./include/linux/printk.h:446:44: error: using a dangling pointer to '__str' [-Werror=dangling-pointer=]
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                                            ^
./include/linux/printk.h:418:17: note: in definition of macro 'printk_index_wrap'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                 ^~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:75:17: note: in expansion of macro 'pr_err'
   75 |                 pr_err("%p: replaced (%s) != old (%s)",
      |                 ^~~~~~
In file included from ./arch/powerpc/include/asm/code-patching.h:14,
                 from arch/powerpc/kernel/trace/ftrace.c:26:
./arch/powerpc/include/asm/inst.h:156:14: note: '__str' declared here
  156 |         char __str[PPC_INST_STR_LEN];   \
      |              ^~~~~
./include/linux/printk.h:418:33: note: in expansion of macro 'ppc_inst_as_str'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                                 ^~~~~~~~~~~
./include/linux/printk.h:446:26: note: in expansion of macro 'printk_index_wrap'
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                          ^~~~~~~~~~~~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:75:17: note: in expansion of macro 'pr_err'
   75 |                 pr_err("%p: replaced (%s) != old (%s)",
      |                 ^~~~~~
arch/powerpc/kernel/trace/ftrace.c: In function '__ftrace_make_nop_kernel':
./include/linux/printk.h:446:44: error: using a dangling pointer to '__str' [-Werror=dangling-pointer=]
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                                            ^
./include/linux/printk.h:418:17: note: in definition of macro 'printk_index_wrap'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                 ^~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:379:17: note: in expansion of macro 'pr_err'
  379 |                 pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
      |                 ^~~~~~
./arch/powerpc/include/asm/inst.h:156:14: note: '__str' declared here
  156 |         char __str[PPC_INST_STR_LEN];   \
      |              ^~~~~
./include/linux/printk.h:418:33: note: in expansion of macro 'ppc_inst_as_str'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                                 ^~~~~~~~~~~
./include/linux/printk.h:446:26: note: in expansion of macro 'printk_index_wrap'
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                          ^~~~~~~~~~~~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:379:17: note: in expansion of macro 'pr_err'
  379 |                 pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
      |                 ^~~~~~
arch/powerpc/kernel/trace/ftrace.c: In function '__ftrace_make_call_kernel':
./include/linux/printk.h:446:44: error: using a dangling pointer to '__str' [-Werror=dangling-pointer=]
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                                            ^
./include/linux/printk.h:418:17: note: in definition of macro 'printk_index_wrap'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                 ^~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:638:17: note: in expansion of macro 'pr_err'
  638 |                 pr_err("Unexpected call sequence at %p: %s\n", ip, ppc_inst_as_str(op));
      |                 ^~~~~~
./arch/powerpc/include/asm/inst.h:156:14: note: '__str' declared here
  156 |         char __str[PPC_INST_STR_LEN];   \
      |              ^~~~~
./include/linux/printk.h:418:33: note: in expansion of macro 'ppc_inst_as_str'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                                 ^~~~~~~~~~~
./include/linux/printk.h:446:26: note: in expansion of macro 'printk_index_wrap'
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                          ^~~~~~~~~~~~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:638:17: note: in expansion of macro 'pr_err'
  638 |                 pr_err("Unexpected call sequence at %p: %s\n", ip, ppc_inst_as_str(op));
      |                 ^~~~~~
arch/powerpc/kernel/trace/ftrace.c: In function '__ftrace_make_nop':
./include/linux/printk.h:446:44: error: using a dangling pointer to '__str' [-Werror=dangling-pointer=]
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                                            ^
./include/linux/printk.h:418:17: note: in definition of macro 'printk_index_wrap'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                 ^~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:205:17: note: in expansion of macro 'pr_err'
  205 |                 pr_err("Expected %08lx found %s\n", PPC_INST_LD_TOC, ppc_inst_as_str(op));
      |                 ^~~~~~
./arch/powerpc/include/asm/inst.h:156:14: note: '__str' declared here
  156 |         char __str[PPC_INST_STR_LEN];   \
      |              ^~~~~
./include/linux/printk.h:418:33: note: in expansion of macro 'ppc_inst_as_str'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                                 ^~~~~~~~~~~
./include/linux/printk.h:446:26: note: in expansion of macro 'printk_index_wrap'
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                          ^~~~~~~~~~~~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:205:17: note: in expansion of macro 'pr_err'
  205 |                 pr_err("Expected %08lx found %s\n", PPC_INST_LD_TOC, ppc_inst_as_str(op));
      |                 ^~~~~~
./include/linux/printk.h:446:44: error: using a dangling pointer to '__str' [-Werror=dangling-pointer=]
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                                            ^
./include/linux/printk.h:418:17: note: in definition of macro 'printk_index_wrap'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                 ^~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:139:17: note: in expansion of macro 'pr_err'
  139 |                 pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
      |                 ^~~~~~
./arch/powerpc/include/asm/inst.h:156:14: note: '__str' declared here
  156 |         char __str[PPC_INST_STR_LEN];   \
      |              ^~~~~
./include/linux/printk.h:418:33: note: in expansion of macro 'ppc_inst_as_str'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                                 ^~~~~~~~~~~
./include/linux/printk.h:446:26: note: in expansion of macro 'printk_index_wrap'
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                          ^~~~~~~~~~~~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:139:17: note: in expansion of macro 'pr_err'
  139 |                 pr_err("Not expected bl: opcode is %s\n", ppc_inst_as_str(op));
      |                 ^~~~~~
arch/powerpc/kernel/trace/ftrace.c: In function '__ftrace_make_call':
./include/linux/printk.h:446:44: error: using a dangling pointer to '__str' [-Werror=dangling-pointer=]
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                                            ^
./include/linux/printk.h:418:17: note: in definition of macro 'printk_index_wrap'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                 ^~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:506:17: note: in expansion of macro 'pr_err'
  506 |                 pr_err("Unexpected call sequence at %p: %s %s\n",
      |                 ^~~~~~
./arch/powerpc/include/asm/inst.h:156:14: note: '__str' declared here
  156 |         char __str[PPC_INST_STR_LEN];   \
      |              ^~~~~
./include/linux/printk.h:418:33: note: in expansion of macro 'ppc_inst_as_str'
  418 |                 _p_func(_fmt, ##__VA_ARGS__);                           \
      |                                 ^~~~~~~~~~~
./include/linux/printk.h:446:26: note: in expansion of macro 'printk_index_wrap'
  446 | #define printk(fmt, ...) printk_index_wrap(_printk, fmt, ##__VA_ARGS__)
      |                          ^~~~~~~~~~~~~~~~~
./include/linux/printk.h:489:9: note: in expansion of macro 'printk'
  489 |         printk(KERN_ERR pr_fmt(fmt), ##__VA_ARGS__)
      |         ^~~~~~
arch/powerpc/kernel/trace/ftrace.c:506:17: note: in expansion of macro 'pr_err'
  506 |                 pr_err("Unexpected call sequence at %p: %s %s\n",
      |                 ^~~~~~
cc1: all warnings being treated as errors
make[3]: *** [scripts/Makefile.build:288: arch/powerpc/kernel/trace/ftrace.o] Error 1

I also hit this error on current master (commit babf0bb978e3c9
("Merge tag 'xfs-5.19-for-linus' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux")).

Thanks.

Reported-by: Bagas Sanjaya <bagasdotme at gmail.com>

-- 
An old man doll... just what I always wanted! - Clara


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