[PATCH v2] selftest/powerpc/benchmark: remove requirement libc-dev

[Michael Ellerman]

Madhavan Srinivasan <maddy at linux.ibm.com> writes:
> Currently exec-target.c file is linked as static and this
> post a requirement to install libc dev package to build.

I think specifically the problem is that the test requires a static
libc, which is packaged separately in some distros from the regular libc
headers, am I right?

On Fedora the package is glibc-static, as opposed to glibc-devel, which
the tests still require.

So this patch removes the requirement to have glibc-static installed.
Any idea what the package is called on Debian/Ubuntu?

cheers

> Without it, build-break when compiling selftest/powerpc/benchmark.
>
>   CC       exec_target
> /usr/bin/ld: cannot find -lc: No such file or directory
> collect2: error: ld returned 1 exit status
>
> exec_target.c is using "syscall" library function which
> could be replaced with a inline assembly and the same is
> proposed as a fix here.
>
> Suggested-by: Michael Ellerman <mpe at ellerman.id.au>
> Signed-off-by: Madhavan Srinivasan <maddy at linux.ibm.com>
> ---
> Chnagelog v1:
> - Add comment for clobber register and proper list of
>   clobber registers as suggested by Michael Ellerman and
>   Christophe Leroy
>
>  .../selftests/powerpc/benchmarks/Makefile        |  2 +-
>  .../selftests/powerpc/benchmarks/exec_target.c   | 16 ++++++++++++++--
>  2 files changed, 15 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/powerpc/benchmarks/Makefile b/tools/testing/selftests/powerpc/benchmarks/Makefile
> index 1321922038d0..ca4483c238b9 100644
> --- a/tools/testing/selftests/powerpc/benchmarks/Makefile
> +++ b/tools/testing/selftests/powerpc/benchmarks/Makefile
> @@ -18,4 +18,4 @@ $(OUTPUT)/context_switch: LDLIBS += -lpthread
>  
>  $(OUTPUT)/fork: LDLIBS += -lpthread
>  
> -$(OUTPUT)/exec_target: CFLAGS += -static -nostartfiles
> +$(OUTPUT)/exec_target: CFLAGS += -nostartfiles
> diff --git a/tools/testing/selftests/powerpc/benchmarks/exec_target.c b/tools/testing/selftests/powerpc/benchmarks/exec_target.c
> index c14b0fc1edde..a6408d3f26cd 100644
> --- a/tools/testing/selftests/powerpc/benchmarks/exec_target.c
> +++ b/tools/testing/selftests/powerpc/benchmarks/exec_target.c
> @@ -7,10 +7,22 @@
>   */
>  
>  #define _GNU_SOURCE
> -#include <unistd.h>
>  #include <sys/syscall.h>
>  
>  void _start(void)
>  {
> -	syscall(SYS_exit, 0);
> +	asm volatile (
> +		"li %%r0, %[sys_exit];"
> +		"li %%r3, 0;"
> +		"sc;"
> +		:
> +		: [sys_exit] "i" (SYS_exit)
> +		/*
> +		 * "sc" will clobber r0, r3-r13, cr0, ctr, xer and memory.
> +		 * Even though sys_exit never returns, handle clobber
> +		 * registers.
> +		 */
> +		: "r0", "r3", "r4", "r5", "r6", "r7", "r8", "r9", "r10",
> +		  "r11", "r12", "r13", "cr0", "ctr", "xer", "memory"
> +	);
>  }
> -- 
> 2.45.2