Define GEN_AS_CONST_HEADERS when generating header files [BZ #22792]
Commit Message
Glibc build generates header files to define constants from special .sym
files. If a .sym file includes the same header file which it generates,
it leads to circular dependency. Define GEN_AS_CONST_HEADERS when
generating header files to avoid circular dependency.
<tcb-offsets.h> is needed for i686 and it isn't needed for x86-64 at
least since glibc 2.23.
Tested on i686 and x86-64.
OK for trunk?
H.J.
---
[BZ #22792]
* Makerules ($(common-objpfx)%.h): Pass -DGEN_AS_CONST_HEADERS
to $(CC).
* sysdeps/unix/sysv/linux/i386/lowlevellock.h: Include
<tcb-offsets.h> only if GEN_AS_CONST_HEADERS isn't defined.
* sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Don't include
<tcb-offsets.h>.
---
Makerules | 4 +++-
sysdeps/unix/sysv/linux/i386/lowlevellock.h | 4 +++-
sysdeps/unix/sysv/linux/x86_64/lowlevellock.h | 1 -
3 files changed, 6 insertions(+), 3 deletions(-)
Comments
On 02/08/2018 06:58 PM, H.J. Lu wrote:
> [BZ #22792]
> * Makerules ($(common-objpfx)%.h): Pass -DGEN_AS_CONST_HEADERS
> to $(CC).
> * sysdeps/unix/sysv/linux/i386/lowlevellock.h: Include
> <tcb-offsets.h> only if GEN_AS_CONST_HEADERS isn't defined.
> * sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Don't include
> <tcb-offsets.h>.
It looks to me that a cleaner fix would be to move the definition of the
TCB types to a separate header.
The circular dependency is just a cosmetic warning from make, right?
Thanks,
Florian
On Tue, Feb 20, 2018 at 11:09 PM, Florian Weimer <fweimer@redhat.com> wrote:
> On 02/08/2018 06:58 PM, H.J. Lu wrote:
>>
>> [BZ #22792]
>> * Makerules ($(common-objpfx)%.h): Pass -DGEN_AS_CONST_HEADERS
>> to $(CC).
>> * sysdeps/unix/sysv/linux/i386/lowlevellock.h: Include
>> <tcb-offsets.h> only if GEN_AS_CONST_HEADERS isn't defined.
>> * sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Don't include
>> <tcb-offsets.h>.
>
>
> It looks to me that a cleaner fix would be to move the definition of the TCB
> types to a separate header.
I will take a look.
> The circular dependency is just a cosmetic warning from make, right?
It depends on how unlucky you are. In one case on a many-core machine
with make -j60, I had to kill glibc build since it never stopped.
On Wed, Feb 21, 2018 at 7:40 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Tue, Feb 20, 2018 at 11:09 PM, Florian Weimer <fweimer@redhat.com> wrote:
>> On 02/08/2018 06:58 PM, H.J. Lu wrote:
>>>
>>> [BZ #22792]
>>> * Makerules ($(common-objpfx)%.h): Pass -DGEN_AS_CONST_HEADERS
>>> to $(CC).
>>> * sysdeps/unix/sysv/linux/i386/lowlevellock.h: Include
>>> <tcb-offsets.h> only if GEN_AS_CONST_HEADERS isn't defined.
>>> * sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Don't include
>>> <tcb-offsets.h>.
>>
>>
>> It looks to me that a cleaner fix would be to move the definition of the TCB
>> types to a separate header.
>
> I will take a look.
sysdeps/i386/nptl/tcb-offsets.sym has
#include <sysdep.h>
#include <tls.h>
#include <kernel-features.h>
RESULT offsetof (struct pthread, result)
TID offsetof (struct pthread, tid)
CANCELHANDLING offsetof (struct pthread, cancelhandling)
CLEANUP_JMP_BUF offsetof (struct pthread, cleanup_jmp_buf)
MULTIPLE_THREADS_OFFSET offsetof (tcbhead_t, multiple_threads)
SYSINFO_OFFSET offsetof (tcbhead_t, sysinfo)
CLEANUP offsetof (struct pthread, cleanup)
CLEANUP_PREV offsetof (struct _pthread_cleanup_buffer, __prev)
MUTEX_FUTEX offsetof (pthread_mutex_t, __data.__lock)
POINTER_GUARD offsetof (tcbhead_t, pointer_guard)
#ifndef __ASSUME_PRIVATE_FUTEX
PRIVATE_FUTEX offsetof (tcbhead_t, private_futex)
#endif
It covers more than just tcbhead_t. A separate header file for tcbhead_t
won't help here.
>> The circular dependency is just a cosmetic warning from make, right?
>
> It depends on how unlucky you are. In one case on a many-core machine
> with make -j60, I had to kill glibc build since it never stopped.
>
>
> --
> H.J.
On 02/21/2018 06:19 PM, H.J. Lu wrote:
> On Wed, Feb 21, 2018 at 7:40 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>> On Tue, Feb 20, 2018 at 11:09 PM, Florian Weimer <fweimer@redhat.com> wrote:
>>> On 02/08/2018 06:58 PM, H.J. Lu wrote:
>>>>
>>>> [BZ #22792]
>>>> * Makerules ($(common-objpfx)%.h): Pass -DGEN_AS_CONST_HEADERS
>>>> to $(CC).
>>>> * sysdeps/unix/sysv/linux/i386/lowlevellock.h: Include
>>>> <tcb-offsets.h> only if GEN_AS_CONST_HEADERS isn't defined.
>>>> * sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Don't include
>>>> <tcb-offsets.h>.
>>>
>>>
>>> It looks to me that a cleaner fix would be to move the definition of the TCB
>>> types to a separate header.
>>
>> I will take a look.
>
> sysdeps/i386/nptl/tcb-offsets.sym has
>
> #include <sysdep.h>
> #include <tls.h>
> #include <kernel-features.h>
>
> RESULT offsetof (struct pthread, result)
> TID offsetof (struct pthread, tid)
> CANCELHANDLING offsetof (struct pthread, cancelhandling)
> CLEANUP_JMP_BUF offsetof (struct pthread, cleanup_jmp_buf)
> MULTIPLE_THREADS_OFFSET offsetof (tcbhead_t, multiple_threads)
> SYSINFO_OFFSET offsetof (tcbhead_t, sysinfo)
> CLEANUP offsetof (struct pthread, cleanup)
> CLEANUP_PREV offsetof (struct _pthread_cleanup_buffer, __prev)
> MUTEX_FUTEX offsetof (pthread_mutex_t, __data.__lock)
> POINTER_GUARD offsetof (tcbhead_t, pointer_guard)
> #ifndef __ASSUME_PRIVATE_FUTEX
> PRIVATE_FUTEX offsetof (tcbhead_t, private_futex)
> #endif
>
> It covers more than just tcbhead_t. A separate header file for tcbhead_t
> won't help here.
Yes, it's more involved.
>>> The circular dependency is just a cosmetic warning from make, right?
>>
>> It depends on how unlucky you are. In one case on a many-core machine
>> with make -j60, I had to kill glibc build since it never stopped.
If it fixes an actual build issue, then I think your patch is
acceptable, although I consider it quite hackish.
But please do add a comment explaining the issue before:
+# ifndef GEN_AS_CONST_HEADERS
Thanks,
Florian
On 02/22/2018 07:11 AM, Florian Weimer wrote:
> On 02/21/2018 06:19 PM, H.J. Lu wrote:
>> On Wed, Feb 21, 2018 at 7:40 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>> On Tue, Feb 20, 2018 at 11:09 PM, Florian Weimer <fweimer@redhat.com> wrote:
>>>> On 02/08/2018 06:58 PM, H.J. Lu wrote:
>>>>>
>>>>> [BZ #22792]
>>>>> * Makerules ($(common-objpfx)%.h): Pass -DGEN_AS_CONST_HEADERS
>>>>> to $(CC).
>>>>> * sysdeps/unix/sysv/linux/i386/lowlevellock.h: Include
>>>>> <tcb-offsets.h> only if GEN_AS_CONST_HEADERS isn't defined.
>>>>> * sysdeps/unix/sysv/linux/x86_64/lowlevellock.h: Don't include
>>>>> <tcb-offsets.h>.
>>>>
>>>>
>>>> It looks to me that a cleaner fix would be to move the definition of the TCB
>>>> types to a separate header.
>>>
>>> I will take a look.
>>
>> sysdeps/i386/nptl/tcb-offsets.sym has
>>
>> #include <sysdep.h>
>> #include <tls.h>
>> #include <kernel-features.h>
>>
>> RESULT offsetof (struct pthread, result)
>> TID offsetof (struct pthread, tid)
>> CANCELHANDLING offsetof (struct pthread, cancelhandling)
>> CLEANUP_JMP_BUF offsetof (struct pthread, cleanup_jmp_buf)
>> MULTIPLE_THREADS_OFFSET offsetof (tcbhead_t, multiple_threads)
>> SYSINFO_OFFSET offsetof (tcbhead_t, sysinfo)
>> CLEANUP offsetof (struct pthread, cleanup)
>> CLEANUP_PREV offsetof (struct _pthread_cleanup_buffer, __prev)
>> MUTEX_FUTEX offsetof (pthread_mutex_t, __data.__lock)
>> POINTER_GUARD offsetof (tcbhead_t, pointer_guard)
>> #ifndef __ASSUME_PRIVATE_FUTEX
>> PRIVATE_FUTEX offsetof (tcbhead_t, private_futex)
>> #endif
>>
>> It covers more than just tcbhead_t. A separate header file for tcbhead_t
>> won't help here.
>
> Yes, it's more involved.
>
>>>> The circular dependency is just a cosmetic warning from make, right?
>>>
>>> It depends on how unlucky you are. In one case on a many-core machine
>>> with make -j60, I had to kill glibc build since it never stopped.
>
> If it fixes an actual build issue, then I think your patch is acceptable, although I consider it quite hackish.
>
> But please do add a comment explaining the issue before:
>
> +# ifndef GEN_AS_CONST_HEADERS
Agreed, I think the hack is OK, but needs a multi-line comment
explaining *why* the simple route of header disentanglement
is not easily possible and why this is needed to bootstrap
the automatic header building without a circular dependency.
@@ -276,10 +276,12 @@ ifdef gen-as-const-headers
# Generating headers for assembly constants.
# We need this defined early to get into before-compile before
# it's used in sysd-rules, below.
+# Define GEN_AS_CONST_HEADERS to avoid circular dependency [BZ #22792].
$(common-objpfx)%.h $(common-objpfx)%.h.d: $(..)scripts/gen-as-const.awk \
%.sym $(common-before-compile)
$(AWK) -f $< $(filter %.sym,$^) \
- | $(CC) -S -o $(@:.h.d=.h)T3 $(CFLAGS) $(CPPFLAGS) -x c - \
+ | $(CC) -S -o $(@:.h.d=.h)T3 $(CFLAGS) $(CPPFLAGS) \
+ -DGEN_AS_CONST_HEADERS -x c - \
-MD -MP -MF $(@:.h=.h.d)T -MT '$(@:.h=.h.d) $(@:.h.d=.h)'
sed -n 's/^.*@@@name@@@\([^@]*\)@@@value@@@[^0-9Xxa-fA-F-]*\([0-9Xxa-fA-F-][0-9Xxa-fA-F-]*\).*@@@end@@@.*$$/#define \1 \2/p' \
$(@:.h.d=.h)T3 > $(@:.h.d=.h)T
@@ -26,7 +26,9 @@
# include <sys/param.h>
# include <bits/pthreadtypes.h>
# include <kernel-features.h>
-# include <tcb-offsets.h>
+# ifndef GEN_AS_CONST_HEADERS
+# include <tcb-offsets.h>
+# endif
# ifndef LOCK_INSTR
# ifdef UP
@@ -26,7 +26,6 @@
# include <sys/param.h>
# include <bits/pthreadtypes.h>
# include <kernel-features.h>
-# include <tcb-offsets.h>
# ifndef LOCK_INSTR
# ifdef UP