[PATCH] selftests/nolibc: Fix up compile error for rv32

[Zhangjin Wu]

Willy, Thomas,

Resend more info about this patch (added but lost after a new format-patch):

This patch is based on the nolibc/20230520-nolibc-rv32+stkp branch of
[1] + the STKP patch for riscv [2], it is a testing 'side-effect' of the
STKP on rv32.

The nolibc rv32 port is not yet functional, we did this compile test by
adding -D__ARCH_WANT_TIME32_SYSCALLS to gcc (only for compile, see [3]).

We did get this info for rv32:

    !!Stack smashing detected!!

Just to mention, -DNOLIBC_STACKPROTECTOR -fstack-protector-all is used to
enable STKP, for -mstack-protector-guard=global is not available for riscv64
gcc 9.3:

    riscv64-linux-gnu-gcc: error: unrecognized command line option '-mstack-protector-guard=global'; did you mean '-fstack-protector-all'

[1]: https://git.kernel.org/pub/scm/linux/kernel/git/wtarreau/nolibc.git
[2]: https://lore.kernel.org/linux-riscv/20230520-nolibc-stackprotector-riscv-v1-1-d8912012a034@weissschuh.net/T/#
[3]: https://lore.kernel.org/linux-riscv/20230520084610.GA27206@1wt.eu/T/#mf0e54ee19bd3f94dadbb4420ed9dffa316d1719d

Best regards,
Zhangjin Wu

> When compile nolibc-test.c for rv32, we got such error:
>
>     tools/testing/selftests/nolibc/nolibc-test.c:599:57: error: '__NR_fstat' undeclared (first use in this function)
>       599 |   CASE_TEST(syscall_args);      EXPECT_SYSER(1, syscall(__NR_fstat, 0, NULL), -1, EFAULT); break;
>
> The generic include/uapi/asm-generic/unistd.h used by rv32 doesn't
> support __NR_fstat, using the common __NR_read functions as expected.
>
>     Running test 'syscall'
>     69 syscall_noargs = 1                                            [OK]
>     70 syscall_args = -1 EBADF                                       [OK]
>
> Btw, the latest riscv libc6-dev package is required, otherwise, we would
> also get such error:
>
>     In file included from /usr/riscv64-linux-gnu/include/sys/cdefs.h:452,
>                      from /usr/riscv64-linux-gnu/include/features.h:461,
>                      from /usr/riscv64-linux-gnu/include/bits/libc-header-start.h:33,
>                      from /usr/riscv64-linux-gnu/include/limits.h:26,
>                      from /usr/lib/gcc-cross/riscv64-linux-gnu/9/include/limits.h:194,
>                      from /usr/lib/gcc-cross/riscv64-linux-gnu/9/include/syslimits.h:7,
>                      from /usr/lib/gcc-cross/riscv64-linux-gnu/9/include/limits.h:34,
>                      from /labs/linux-lab/src/linux-stable/tools/testing/selftests/nolibc/nolibc-test.c:6:
>     /usr/riscv64-linux-gnu/include/bits/wordsize.h:28:3: error: #error "rv32i-based targets are not supported"
>        28 | # error "rv32i-based targets are not supported"
>
> The glibc commit 5b6113d62efa ("RISC-V: Support the 32-bit ABI
> implementation") fixed up above error, so, glibc >= 2.33 (who includes
> this commit) is required.
>
> Signed-off-by: Zhangjin Wu <falcon at tinylab.org>
> ---
>  tools/testing/selftests/nolibc/nolibc-test.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
> index 063f9959ac44..d8b59c8f6c03 100644
> --- a/tools/testing/selftests/nolibc/nolibc-test.c
> +++ b/tools/testing/selftests/nolibc/nolibc-test.c
> @@ -596,7 +596,7 @@ int run_syscall(int min, int max)
>  		CASE_TEST(write_badf);        EXPECT_SYSER(1, write(-1, &tmp, 1), -1, EBADF); break;
>  		CASE_TEST(write_zero);        EXPECT_SYSZR(1, write(1, &tmp, 0)); break;
>  		CASE_TEST(syscall_noargs);    EXPECT_SYSEQ(1, syscall(__NR_getpid), getpid()); break;
> -		CASE_TEST(syscall_args);      EXPECT_SYSER(1, syscall(__NR_fstat, 0, NULL), -1, EFAULT); break;
> +		CASE_TEST(syscall_args);      EXPECT_SYSER(1, syscall(__NR_read, -1, &tmp, 1), -1, EBADF); break;
>  		case __LINE__:
>  			return ret; /* must be last */
>  		/* note: do not set any defaults so as to permit holes above */