Re: stap make check - process_test and sched_test failure

[Li Guanglei <guanglei at cn dot ibm dot com>]

Roland McGrath ??:
> Please sort out among these which ones are which.  The ones that have no
> location might be inlined constant parameters or something.  The compiler
> could do better on those.  Or maybe it's just plain compiler bugs that
> cause them to be missing.
>
>
> Thanks,
> Roland

  Sorry, today when I tried objdump using the address of DW_AT_low_pc 
in DW_TAG_inlined_subroutine, I realized that I was looking at 
handle_signal for ppc32(signal_32.c). The following is the DWARF info 
for handle_signal on ppc64 kernel(signal_64.c). You can see that the 
compiler won't generate the arguments location info for this concrete 
instance of handle_signal.

  The signature of handle_signal on ppc64 is:

static int handle_signal(unsigned long sig, struct k_sigaction *ka,
                         siginfo_t *info, sigset_t *oldset, struct 
pt_regs *regs)

...
 <1><b7ffb>: Abbrev Number: 65 (DW_TAG_subprogram)
     DW_AT_sibling     : <b8055>
     DW_AT_name        : (indirect string, offset: 0x5525): handle_signal
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 446
     DW_AT_prototyped  : 1
     DW_AT_type        : <afa76>
     DW_AT_inline      : 1      (inlined)
 <2><b800d>: Abbrev Number: 66 (DW_TAG_formal_parameter)
     DW_AT_name        : sig
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 444
     DW_AT_type        : <afa63>
 <2><b8019>: Abbrev Number: 66 (DW_TAG_formal_parameter)
     DW_AT_name        : ka
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 444
     DW_AT_type        : <b7ff5>
 <2><b8024>: Abbrev Number: 67 (DW_TAG_formal_parameter)
     DW_AT_name        : (indirect string, offset: 0x68a62): info
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 445
     DW_AT_type        : <b31a1>
 <2><b8030>: Abbrev Number: 67 (DW_TAG_formal_parameter)
     DW_AT_name        : (indirect string, offset: 0x5633): oldset
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 445
     DW_AT_type        : <b3165>
 <2><b803c>: Abbrev Number: 67 (DW_TAG_formal_parameter)
     DW_AT_name        : (indirect string, offset: 0xa0700): regs
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 445
     DW_AT_type        : <b01b7>

...

 <3><b785d>: Abbrev Number: 56 (DW_TAG_inlined_subroutine)
     DW_AT_sibling     : <b7d86>
     DW_AT_abstract_origin: <b7ffb>
     DW_AT_low_pc      : 0x15928
     DW_AT_high_pc     : 0x15d30
     DW_AT_call_file   : 0
     DW_AT_call_line   : 0
 <4><b7878>: Abbrev Number: 57 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <b800d>
 <4><b787d>: Abbrev Number: 57 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <b8019>
 <4><b7882>: Abbrev Number: 57 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <b8024>
 <4><b7887>: Abbrev Number: 57 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <b8030>
 <4><b788c>: Abbrev Number: 57 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <b803c>


  As a comparision, I also paste the DWARF info for handle_signal on 
ppc32. You can see that GCC generate the loc info for part of 
arguments of handle_signal:

handle_signal is declared as the following in ppc32:

static int handle_signal(unsigned long sig, struct k_sigaction *ka,
                siginfo_t *info, sigset_t *oldset, struct pt_regs *regs,
                unsigned long newsp)
...
 <1><671e1>: Abbrev Number: 77 (DW_TAG_subprogram)
     DW_AT_sibling     : <67316>
     DW_AT_name        : (indirect string, offset: 0x5525): handle_signal
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 1008
     DW_AT_prototyped  : 1
     DW_AT_type        : <5e0be>
     DW_AT_inline      : 1      (inlined)
 <2><671f3>: Abbrev Number: 78 (DW_TAG_formal_parameter)
     DW_AT_name        : sig
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 1005
     DW_AT_type        : <5e0ab>
 <2><671ff>: Abbrev Number: 78 (DW_TAG_formal_parameter)
     DW_AT_name        : ka
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 1005
     DW_AT_type        : <64fd0>
 <2><6720a>: Abbrev Number: 79 (DW_TAG_formal_parameter)
     DW_AT_name        : (indirect string, offset: 0x68a62): info
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 1006
     DW_AT_type        : <6176a>
 <2><67216>: Abbrev Number: 79 (DW_TAG_formal_parameter)
     DW_AT_name        : (indirect string, offset: 0x5633): oldset
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 1006
     DW_AT_type        : <6172e>
 <2><67222>: Abbrev Number: 79 (DW_TAG_formal_parameter)
     DW_AT_name        : (indirect string, offset: 0xa0700): regs
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 1006
     DW_AT_type        : <5e787>
 <2><6722e>: Abbrev Number: 79 (DW_TAG_formal_parameter)
     DW_AT_name        : (indirect string, offset: 0x5606): newsp
     DW_AT_decl_file   : 1
     DW_AT_decl_line   : 1007
     DW_AT_type        : <5e0ab>
...
 <2><66bf9>: Abbrev Number: 48 (DW_TAG_inlined_subroutine)
     DW_AT_sibling     : <66d87>
     DW_AT_abstract_origin: <671e1>
     DW_AT_low_pc      : 0xda70
     DW_AT_high_pc     : 0xdbe4
     DW_AT_call_file   : 0
     DW_AT_call_line   : 0
 <3><66c14>: Abbrev Number: 54 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <671f3>
     DW_AT_location    : 66492  (location list)
 <3><66c1d>: Abbrev Number: 49 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <671ff>
 <3><66c22>: Abbrev Number: 49 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <6720a>
 <3><66c27>: Abbrev Number: 49 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <67216>
 <3><66c2c>: Abbrev Number: 54 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <67222>
     DW_AT_location    : 66527  (location list)
 <3><66c35>: Abbrev Number: 54 (DW_TAG_formal_parameter)
     DW_AT_abstract_origin: <6722e>
     DW_AT_location    : 66581  (location list)
...

- Guanglei