[REGRESSION] testing/selftests/x86/ pkeys build failures (was: Re: [PATCH] mm, x86: pkeys: Introduce PKEY_ALLOC_SIGNALINHERIT and change signal semantics)

* Florian Weimer [off-list ref] wrote:

This patch is based on the previous discussion (pkeys: Support setting
access rights for signal handlers):

  https://marc.info/?t=151285426000001

It aligns the signal semantics of the x86 implementation with the upcoming
POWER implementation, and defines a new flag, so that applications can
detect which semantics the kernel uses.

A change in this area is needed to make memory protection keys usable for
protecting the GOT in the dynamic linker.

(Feel free to replace the trigraphs in the commit message before committing,
or to remove the program altogether.)

Could you please send patches not as MIME attachments?

Also, the protection keys testcase first need to be fixed, before we complicate 
them - for example on a pretty regular Ubuntu x86-64 installation they fail to 
build with the build errors attached further below.

On an older Fedora 23 installation, the testcases themselves don't build at all:

 fomalhaut:~/tip2/tools/testing/selftests/x86> make protection_keys
 gcc -O2 -g -std=gnu99 -pthread -Wall -no-pie    protection_keys.c   -o protection_keys
 gcc: error: unrecognized command line option ‘-no-pie’
 <builtin>: recipe for target 'protection_keys' failed
 make: *** [protection_keys] Error 1

so it's one big mess at the moment that needs some love ...

Thanks,

	Ingo

==================>

triton:~/tip/tools/testing/selftests/x86> make
gcc -m32 -o /home/mingo/tip/tools/testing/selftests/x86/protection_keys_32 -O2 -g -std=gnu99 -pthread -Wall -no-pie  protection_keys.c -lrt -ldl -lm
In file included from /usr/include/signal.h:57:0,
                 from protection_keys.c:33:
protection_keys.c: In function ‘signal_handler’:
protection_keys.c:253:6: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__attribute__’ before ‘.’ token
  u64 si_pkey;
      ^
protection_keys.c:253:6: error: expected expression before ‘.’ token
protection_keys.c:295:2: error: ‘_sifields’ undeclared (first use in this function)
  si_pkey = *si_pkey_ptr;
  ^
protection_keys.c:295:2: note: each undeclared identifier is reported only once for each function it appears in
In file included from protection_keys.c:46:0:
pkey-helpers.h: In function ‘sigsafe_printf’:
pkey-helpers.h:42:3: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result]
   write(1, dprint_in_signal_buffer, len);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
protection_keys.c: In function ‘dumpit’:
protection_keys.c:419:3: warning: ignoring return value of ‘write’, declared with attribute warn_unused_result [-Wunused-result]
   write(1, buf, nr_read);
   ^~~~~~~~~~~~~~~~~~~~~~
Makefile:47: recipe for target '/home/mingo/tip/tools/testing/selftests/x86/protection_keys_32' failed

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