2018-03-05 22:48 GMT+08:00 Petr Mladek <pmla...@suse.com>: > On Mon 2018-03-05 14:37:42, Sergey Senozhatsky wrote: >> We want to move dump_stack related functions out of printk C >> code and consolidate them in lib/dump_stack file. The reason why >> dump_stack_print_info()/etc ended up in printk.c was a "generic" >> (dummy) lib dump_stack() function, which archs can override. >> For example, blackfin and nds32, define their own EXPORT_SYMBOL >> dump_stack() functions. >> >> In case of blackfin that arch-specific dump_stack() symbol invokes >> a global dump_stack_print_info() function. So we can't easily move >> dump_stack_print_info() to lib/dump_stack, because this way we will >> link with lib/dump_stack.o file, which will bring in a generic >> dump_stack() symbol with it, causing a multiple definitions error: >> - one dump_stack() from arch/blackfin/dumpstack >> - the other one from lib/dump_stack >> >> Convert generic dump_stack() into a weak symbol. So we will be >> able link with lib/dump_stack and at the same time archs will >> be able to override dump_stack(). It also opens up a way for us >> to move dump_stack_set_arch_desc(), dump_stack_print_info() and >> show_regs_print_info() to lib/dump_stack. >> >> Signed-off-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com> >> --- >> arch/blackfin/kernel/dumpstack.c | 1 - >> arch/nds32/kernel/traps.c | 2 -- >> lib/dump_stack.c | 4 ++-- >> 3 files changed, 2 insertions(+), 5 deletions(-) >> >> diff --git a/arch/blackfin/kernel/dumpstack.c >> b/arch/blackfin/kernel/dumpstack.c >> index 3c992c1f8ef2..61af017130cd 100644 >> --- a/arch/blackfin/kernel/dumpstack.c >> +++ b/arch/blackfin/kernel/dumpstack.c >> @@ -174,4 +174,3 @@ void dump_stack(void) >> show_stack(current, &stack); >> trace_buffer_restore(tflags); >> } >> -EXPORT_SYMBOL(dump_stack); > > I was afraid that blackfin modules would not longer be able > to use arch-specific dump_stack symbol. But it seems that only > the symbol name is important. Alos the list of symbols look > promissing: > > before: > > $> objdump -x vmlinux | less | grep dump_stack > 00248530 l O __ksymtab 00000008 ___ksymtab_dump_stack > 002500d4 l O __ksymtab_strings 0000000c ___kstrtab_dump_stack > 00272bb6 l O .bss 00000080 _dump_stack_arch_desc_str > 000051a8 g F .text 00000042 _dump_stack > 002ab05c g F .init.text 0000002a _dump_stack_set_arch_desc > 0003051c g F .text 000000a4 _dump_stack_print_info > > > after: > > $> objdump -x vmlinux.patched | less | grep dump_stack > 00000000 l df *ABS* 00000000 lib/dump_stack.c > 0027c3e8 l O .bss 00000080 _dump_stack_arch_desc_str > 00248580 l O __ksymtab 00000008 ___ksymtab_dump_stack > 002653d4 l O __ksymtab_strings 0000000c ___kstrtab_dump_stack > 000051a8 g F .text 00000042 _dump_stack > 002b69dc g F .init.text 0000002a _dump_stack_set_arch_desc > 001c2a90 g F .text 000000a4 _dump_stack_print_info > > I hope that I did not miss anything. I could not try this at > runtime. I could just cross-compile. > > Anyway, from my side: > > Reviewed-by: Petr Mladek <pmla...@suse.com> > > I'll wait a bit and push it into printk.git for-4.17. > > > Greentime Hu, you tested this on nds32. Could I use your Tested-by, > please? >
Yes, please use it. :) greentime@atcsqa02:/NOBACKUP/sqa2/greentime/contrib/src_pkg/linux-next <next-20180302> $ nds32le-elf-objdump -x vmlinux | less | grep dump_stack 00000000 l df *ABS* 00000000 dump_stack.c b04f7910 l O .bss 00000080 dump_stack_arch_desc_str b04995e8 l O __ksymtab 00000008 __ksymtab_dump_stack b04b9086 l O __ksymtab_strings 0000000b __kstrtab_dump_stack b002a464 g F .text 00000022 dump_stack b03a568c g F .text 000000c2 dump_stack_print_info b0024cf4 g F .init.text 00000038 dump_stack_set_arch_desc
