Re: [PATCH] selftest/powerpc: Add test for sigreturn in transaction

[Cyril Bur <cyrilbur@gmail.com>]

On Mon, 2016-08-22 at 18:53 +0200, Laurent Dufour wrote:
> Ensure that kernel is throwing away the suspended transaction when
> sigreturn() is called otherwise it if fails to restore the signal
> frame's TM SPRS.
> 
> Signed-off-by: Laurent Dufour <ldufour@linux.vnet.ibm.com>

Reviewed-by: Cyril Bur <cyrilbur@gmail.com>

> ---
>  tools/testing/selftests/powerpc/tm/Makefile       |  2 +-
>  tools/testing/selftests/powerpc/tm/tm-sigreturn.c | 89
> +++++++++++++++++++++++
>  2 files changed, 90 insertions(+), 1 deletion(-)
>  create mode 100644 tools/testing/selftests/powerpc/tm/tm-sigreturn.c
> 
> diff --git a/tools/testing/selftests/powerpc/tm/Makefile
> b/tools/testing/selftests/powerpc/tm/Makefile
> index 9d301d785d9e..5e0396d79c8a 100644
> --- a/tools/testing/selftests/powerpc/tm/Makefile
> +++ b/tools/testing/selftests/powerpc/tm/Makefile
> @@ -1,5 +1,5 @@
>  TEST_PROGS := tm-resched-dscr tm-syscall tm-signal-msr-resv tm-
> signal-stack \
> -	tm-vmxcopy tm-fork tm-tar tm-tmspr tm-exec tm-execed
> +	tm-vmxcopy tm-fork tm-tar tm-tmspr tm-exec tm-execed tm-
> sigreturn
>  
>  all: $(TEST_PROGS)
>  
> diff --git a/tools/testing/selftests/powerpc/tm/tm-sigreturn.c
> b/tools/testing/selftests/powerpc/tm/tm-sigreturn.c
> new file mode 100644
> index 000000000000..43fa83de23a5
> --- /dev/null
> +++ b/tools/testing/selftests/powerpc/tm/tm-sigreturn.c
> @@ -0,0 +1,89 @@
> +/*
> + * Copyright 2015, Laurent Dufour, IBM Corp.
> + * Licensed under GPLv2.
> + *
> + * Test the kernel's signal returning code to check reclaim is done
> if
> + * the sigreturn() is called while in a transaction (suspended since
> active
> + * is already dropped trough the system call path).
> + *
> + * The kernel must discard the transaction when entering sigreturn,
> + * since restoring the potential TM SPRS from the signal frame is
> requiring to
> + * not be in a transaction.
> + */
> +
> +#include <unistd.h>
> +#include <sys/types.h>
> +#include <sys/wait.h>
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <signal.h>
> +#include <string.h>
> +
> +#include "utils.h"
> +#include "tm.h"
> +
> +
> +void handler(int sig)
> +{
> +	uint64_t ret;
> +
> +	asm __volatile__(
> +		"li             3,1             ;"
> +		"tbegin.                        ;"
> +		"beq            1f              ;"
> +		"li             3,0             ;"
> +		"tsuspend.                      ;"
> +		"1:                             ;"
> +		"std%X[ret]     3, %[ret]       ;"
> +		: [ret]"=m"(ret)
> +		:
> +		: "memory", "3", "cr0");
> +
> +	if (ret)
> +		exit(1);
> +
> +	/*
> +	 * We return from the signal handle while in a suspended
> transaction
> +	 */
> +}
> +
> +
> +int tm_sigreturn(void)
> +{
> +	struct sigaction sa;
> +	uint64_t ret = 0;
> +
> +	memset(&sa, 0, sizeof(sa));
> +	sa.sa_handler = handler;
> +	sigemptyset(&sa.sa_mask);
> +
> +	if (sigaction(SIGSEGV, &sa, NULL))
> +		exit(1);
> +
> +	asm __volatile__(
> +		"tbegin.                        ;"
> +		"beq            1f              ;"
> +		"li             3,0             ;"
> +		"std            3,0(3)          ;" /* trigger SEGV
> */
> +		"li             3,1             ;"
> +		"std%X[ret]     3,%[ret]        ;"
> +		"tend.                          ;"
> +		"b              2f              ;"
> +		"1:                             ;"
> +		"li             3,2             ;"
> +		"std%X[ret]     3,%[ret]        ;"
> +		"2:                             ;"
> +		: [ret]"=m"(ret)
> +		:
> +		: "memory", "3", "cr0");
> +
> +	if (ret != 2)
> +		exit(1);
> +
> +	exit(0);
> +}
> +
> +int main(void)
> +{
> +	return test_harness(tm_sigreturn, "tm_sigreturn");
> +}