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Bug 1423460

Summary: DW_AT_decl_file and DW_AT_decl_line incorrectly generated
Product: Red Hat Enterprise Linux 7 Reporter: Stanislav Kozina <skozina>
Component: gccAssignee: Jakub Jelinek <jakub>
Status: CLOSED ERRATA QA Contact: Michael Petlan <mpetlan>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 7.4CC: hsowa, mcermak, mpetlan, mpolacek, skozina, ykaliuta
Target Milestone: rc   
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: gcc-4.8.5-12.el7 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2017-08-01 22:35:59 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Attachments:
Description Flags
Preprocessed file none

Description Stanislav Kozina 2017-02-17 11:37:32 UTC
Hello,

We are looking at DWARF data for the kernel ABI verification in RHEL-7. This is what we're seeing in kernel-debuginfo-3.10.0-229.el7.x86_64, the DW_AT_decl_line and DW_AT_decl_file for enum blk_eh_timer_return don't seem correct.

$ readelf --debug=info /usr/lib/debug/lib/modules/3.10.0-229.el7.x86_64/kernel/drivers/ata/libata.ko.debug | less
...
  Compilation Unit @ offset 0x985a5:
   Length:        0x148fa (32-bit)
   Version:       4
   Abbrev Offset: 0x2ecd
   Pointer Size:  8
 <0><985b0>: Abbrev Number: 1 (DW_TAG_compile_unit)
...
    <985b5>   DW_AT_language    : 1     (ANSI C)
    <985b6>   DW_AT_name        : (indirect string, offset: 0x63c38): drivers/ata/libata-acpi.c

### ^^^ This is the name of the CU we'll be looking at ###

    <985ba>   DW_AT_comp_dir    : (indirect string, offset: 0x5f70a): /usr/src/debug/kernel-3.10.0-229.el7/linux-3.10.0-229.el7.x86_64
    <985be>   DW_AT_low_pc      : 0x19ba0
    <985c6>   DW_AT_high_pc     : 0x1591
    <985ce>   DW_AT_stmt_list   : 0xab78

### ^^^ Note the stmt offset here ###

...
 <1><a72f7>: Abbrev Number: 50 (DW_TAG_enumeration_type)
    <a72f8>   DW_AT_name        : (indirect string, offset: 0x5b7af): blk_eh_timer_return
    <a72fc>   DW_AT_byte_size   : 4
    <a72fd>   DW_AT_decl_file   : 133
    <a72fe>   DW_AT_decl_line   : 361

### ^^^ Note the file and line here ###

    <a7300>   DW_AT_sibling     : <0xa7317>
 <2><a7304>: Abbrev Number: 11 (DW_TAG_enumerator)
    <a7305>   DW_AT_name        : (indirect string, offset: 0x60e5d): BLK_EH_NOT_HANDLED
    <a7309>   DW_AT_const_value : 0
 <2><a730a>: Abbrev Number: 11 (DW_TAG_enumerator)
    <a730b>   DW_AT_name        : (indirect string, offset: 0x5bfe6): BLK_EH_HANDLED
    <a730f>   DW_AT_const_value : 1
 <2><a7310>: Abbrev Number: 11 (DW_TAG_enumerator)
    <a7311>   DW_AT_name        : (indirect string, offset: 0x5ac40): BLK_EH_RESET_TIMER
    <a7315>   DW_AT_const_value : 2

### ^^^ This is correct definition of the enum blk_eh_timer_return ###

So, we see that the line of the blk_eh_timer return is defined as 361.

If we then look at the .debug_line section for the file information:

$ readelf --debug=line /usr/lib/debug/lib/modules/3.10.0-229.el7.x86_64/kernel/drivers/ata/libata.ko.debug | less
...
  Offset:                      0xab78
...
 The Directory Table (offset 0xab93):

### ^^^ This is our stmt offset ###

  1     drivers/ata
  2     include/linux
  3     include/uapi/asm-generic
  4     include/asm-generic
  5 /usr/src/debug/kernel-3.10.0-229.el7/linux-3.10.0-229.el7.x86_64/include/uapi/asm-generic
  6     include/uapi/linux
  7 /usr/src/debug/kernel-3.10.0-229.el7/linux-3.10.0-229.el7.x86_64/arch/x86/include/asm
  8     include/acpi
  9 /usr/src/debug/kernel-3.10.0-229.el7/linux-3.10.0-229.el7.x86_64/include/uapi/linux
  10    include/scsi
  11    XXXXXXXXXXXXXXXXXXXX

 The File Name Table (offset 0xad21):
  Entry Dir     Time    Size    Name
...
  133   10      0       0       scsi_host.h

So the DW_AT_decl_file corresponds to include/scsi/scsi_host.h. In that file we see:

$ nl -ba /usr/src/debug/kernel-3.10.0-229.el7/linux-3.10.0-229.el7.x86_64/include/scsi/scsi_host.h | grep 361
   361		enum blk_eh_timer_return (*eh_timed_out)(struct scsi_cmnd *);

This is one of the fields in the struct scsi_host_template, and it does not define the enum blk_eh_timer. So are the DW_AT_decl_line and DW_AT_decl_file incorrectly generated by the gcc?

Comment 2 Jakub Jelinek 2017-03-07 18:26:59 UTC
Can you please attach preprocessed source for the CU that you see this on and mention the full gcc command line used to compile it?  Thanks.

Comment 4 Yauheni Kaliuta 2017-03-07 19:10:15 UTC
Created attachment 1260928 [details]
Preprocessed file

Comment 5 Yauheni Kaliuta 2017-03-07 19:12:59 UTC
A bit better gcc command:

/var/lib/mock/epel-7-x86_64/root/bin/gcc -Wp,-MD,drivers/ata/.libata-acpi.o.d  -nostdinc -isystem /var/lib/mock/epel-7-x86_64/root/usr/bin/../lib/gcc/x86_64-redhat-linux/4.8.5/include -I/kernel_compile_dir/arch/x86/include -Iarch/x86/include/generated  -Iinclude -I/kernel_compile_dir/arch/x86/include/uapi -Iarch/x86/include/generated/uapi -I/kernel_compile_dir/include/uapi -Iinclude/generated/uapi -include /kernel_compile_dir/include/linux/kconfig.h -D__KERNEL__ -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -Werror-implicit-function-declaration -Wno-format-security -fno-delete-null-pointer-checks -Werror -O2 -m64 -mno-sse -mpreferred-stack-boundary=3 -mtune=generic -mno-red-zone -mcmodel=kernel -funit-at-a-time -maccumulate-outgoing-args -Wframe-larger-than=2048 -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1 -DCONFIG_AS_FXSAVEQ=1 -DCONFIG_AS_AVX=1 -DCONFIG_AS_AVX2=1 -pipe -Wno-sign-compare -fno-asynchronous-unwind-tables -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -Wframe-larger-than=2048 -fstack-protector-strong -Wno-unused-but-set-variable -fno-omit-frame-pointer -fno-optimize-sibling-calls -g -pg -mfentry -DCC_USING_FENTRY -fno-inline-functions-called-once -Wdeclaration-after-statement -Wno-pointer-sign -fno-strict-overflow -fconserve-stack -DCC_HAVE_ASM_GOTO  -DMODULE  -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(libata_acpi)"  -D"KBUILD_MODNAME=KBUILD_STR(libata)" -c -o drivers/ata/.tmp_libata-acpi.o drivers/ata/libata-acpi.c

Comment 6 Jakub Jelinek 2017-03-09 06:29:45 UTC
So this boils down to

enum A foo (void);

enum A
{
  B = 1,
  C = 2
};

void
bar (void)
{
  enum A a = C;
}

in C and

enum A : int;

enum A : int
{
  B = 1,
  C = 2
};

void
bar (void)
{
  enum A a = C;
}

in C++, with -g -dA gcc gives DW_AT_line 1 for the enum while g++ gives DW_AT_line 3 for the enum.  C picks the location from the forward declaration, C++ from the definition, even with latest gcc trunk.  I'll have a look.

Comment 7 Stanislav Kozina 2017-03-09 09:20:05 UTC
Thanks Jakub! And thanks Yauheni for providing the requested information faster than me;-)

Comment 9 Michael Petlan 2017-05-31 14:16:01 UTC
The related test passes on all architectures with gcc-4.8.5-14.el7.
VERIFIED.

Comment 10 errata-xmlrpc 2017-08-01 22:35:59 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2017:2094