Subject: Re: [PATCH v14 05/15] selftests/powerpc: Add ptrace tests for GPR/FPR registers in TM

From: Cyril Bur <[email-masked]>
Date: Wed, 14 Sep 2016 14:51:20 +1000

On Mon, 2016-09-12 at 15:33 +0800, [email-masked] wrote:
> From: Anshuman Khandual <[email-masked]>
> 
> This patch adds ptrace interface test for GPR/FPR registers
> inside TM context. This adds ptrace interface based helper
> functions related to checkpointed GPR/FPR access.
> 
> Signed-off-by: Anshuman Khandual <[email-masked]>
> Signed-off-by: Simon Guo <[email-masked]>
> ---
>  tools/testing/selftests/powerpc/ptrace/Makefile    |   3 +-
>  .../selftests/powerpc/ptrace/ptrace-tm-gpr.c       | 296
> +++++++++++++++++++++
>  2 files changed, 298 insertions(+), 1 deletion(-)
>  create mode 100644 tools/testing/selftests/powerpc/ptrace/ptrace-tm-
> gpr.c
> 
> diff --git a/tools/testing/selftests/powerpc/ptrace/Makefile
> b/tools/testing/selftests/powerpc/ptrace/Makefile
> index 31e8e33..170683a 100644
> --- a/tools/testing/selftests/powerpc/ptrace/Makefile
> +++ b/tools/testing/selftests/powerpc/ptrace/Makefile
> @@ -1,8 +1,9 @@
> -TEST_PROGS := ptrace-ebb ptrace-gpr
> +TEST_PROGS := ptrace-ebb ptrace-gpr ptrace-tm-gpr
>  
>  all: $(TEST_PROGS)
>  CFLAGS += -m64
>  $(TEST_PROGS): ../harness.c ptrace.S ../utils.c ptrace.h
>  ptrace-ebb: ../pmu/event.c ../pmu/lib.c ../pmu/ebb/ebb_handler.S
> ../pmu/ebb/busy_loop.S
> +
>  clean:
>  	rm -f $(TEST_PROGS) *.o
> diff --git a/tools/testing/selftests/powerpc/ptrace/ptrace-tm-gpr.c
> b/tools/testing/selftests/powerpc/ptrace/ptrace-tm-gpr.c
> new file mode 100644
> index 0000000..8417d04
> --- /dev/null
> +++ b/tools/testing/selftests/powerpc/ptrace/ptrace-tm-gpr.c
> @@ -0,0 +1,296 @@
> +/*
> + * Ptrace test for GPR/FPR registers in TM context
> + *
> + * Copyright (C) 2015 Anshuman Khandual, IBM Corporation.
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
> +#include "ptrace.h"
> +#include "ptrace-gpr.h"
> +
> +/* Tracer and Tracee Shared Data */
> +int shm_id;
> +volatile unsigned long *cptr, *pptr;
> +
> +float a = FPR_1;
> +float b = FPR_2;
> +float c = FPR_3;
> +
> +void tm_gpr(void)
> +{
> +	unsigned long gpr_buf[18];
> +	unsigned long result, texasr;
> +	float fpr_buf[32];
> +
> +	printf("Starting the child\n");
> +	cptr = (unsigned long *)shmat(shm_id, NULL, 0);
> +
> +trans:
> +	cptr[1] = 0;
> +	asm __volatile__(
> +
> +		"li 14, %[gpr_1];"
> +		"li 15, %[gpr_1];"
> +		"li 16, %[gpr_1];"
> +		"li 17, %[gpr_1];"
> +		"li 18, %[gpr_1];"
> +		"li 19, %[gpr_1];"
> +		"li 20, %[gpr_1];"
> +		"li 21, %[gpr_1];"
> +		"li 22, %[gpr_1];"
> +		"li 23, %[gpr_1];"
> +		"li 24, %[gpr_1];"
> +		"li 25, %[gpr_1];"
> +		"li 26, %[gpr_1];"
> +		"li 27, %[gpr_1];"
> +		"li 28, %[gpr_1];"
> +		"li 29, %[gpr_1];"
> +		"li 30, %[gpr_1];"
> +		"li 31, %[gpr_1];"
> +
> +		"lfs 0, 0(%[flt_1]);"
> +		"lfs 1, 0(%[flt_1]);"
> +		"lfs 2, 0(%[flt_1]);"
> +		"lfs 3, 0(%[flt_1]);"
> +		"lfs 4, 0(%[flt_1]);"
> +		"lfs 5, 0(%[flt_1]);"
> +		"lfs 6, 0(%[flt_1]);"
> +		"lfs 7, 0(%[flt_1]);"
> +		"lfs 8, 0(%[flt_1]);"
> +		"lfs 9, 0(%[flt_1]);"
> +		"lfs 10, 0(%[flt_1]);"
> +		"lfs 11, 0(%[flt_1]);"
> +		"lfs 12, 0(%[flt_1]);"
> +		"lfs 13, 0(%[flt_1]);"
> +		"lfs 14, 0(%[flt_1]);"
> +		"lfs 15, 0(%[flt_1]);"
> +		"lfs 16, 0(%[flt_1]);"
> +		"lfs 17, 0(%[flt_1]);"
> +		"lfs 18, 0(%[flt_1]);"
> +		"lfs 19, 0(%[flt_1]);"
> +		"lfs 20, 0(%[flt_1]);"
> +		"lfs 21, 0(%[flt_1]);"
> +		"lfs 22, 0(%[flt_1]);"
> +		"lfs 23, 0(%[flt_1]);"
> +		"lfs 24, 0(%[flt_1]);"
> +		"lfs 25, 0(%[flt_1]);"
> +		"lfs 26, 0(%[flt_1]);"
> +		"lfs 27, 0(%[flt_1]);"
> +		"lfs 28, 0(%[flt_1]);"
> +		"lfs 29, 0(%[flt_1]);"
> +		"lfs 30, 0(%[flt_1]);"
> +		"lfs 31, 0(%[flt_1]);"
> +

There was this in the previous patch? Can we consolidate?

> +		"1: ;"
> +		TBEGIN

tbegin. is probably fine

> +		"beq 2f;"
> +
> +		"li 14, %[gpr_2];"
> +		"li 15, %[gpr_2];"
> +		"li 16, %[gpr_2];"
> +		"li 17, %[gpr_2];"
> +		"li 18, %[gpr_2];"
> +		"li 19, %[gpr_2];"
> +		"li 20, %[gpr_2];"
> +		"li 21, %[gpr_2];"
> +		"li 22, %[gpr_2];"
> +		"li 23, %[gpr_2];"
> +		"li 24, %[gpr_2];"
> +		"li 25, %[gpr_2];"
> +		"li 26, %[gpr_2];"
> +		"li 27, %[gpr_2];"
> +		"li 28, %[gpr_2];"
> +		"li 29, %[gpr_2];"
> +		"li 30, %[gpr_2];"
> +		"li 31, %[gpr_2];"
> +
> +
> +		"lfs 0, 0(%[flt_2]);"
> +		"lfs 1, 0(%[flt_2]);"
> +		"lfs 2, 0(%[flt_2]);"
> +		"lfs 3, 0(%[flt_2]);"
> +		"lfs 4, 0(%[flt_2]);"
> +		"lfs 5, 0(%[flt_2]);"
> +		"lfs 6, 0(%[flt_2]);"
> +		"lfs 7, 0(%[flt_2]);"
> +		"lfs 8, 0(%[flt_2]);"
> +		"lfs 9, 0(%[flt_2]);"
> +		"lfs 10, 0(%[flt_2]);"
> +		"lfs 11, 0(%[flt_2]);"
> +		"lfs 12, 0(%[flt_2]);"
> +		"lfs 13, 0(%[flt_2]);"
> +		"lfs 14, 0(%[flt_2]);"
> +		"lfs 15, 0(%[flt_2]);"
> +		"lfs 16, 0(%[flt_2]);"
> +		"lfs 17, 0(%[flt_2]);"
> +		"lfs 18, 0(%[flt_2]);"
> +		"lfs 19, 0(%[flt_2]);"
> +		"lfs 20, 0(%[flt_2]);"
> +		"lfs 21, 0(%[flt_2]);"
> +		"lfs 22, 0(%[flt_2]);"
> +		"lfs 23, 0(%[flt_2]);"
> +		"lfs 24, 0(%[flt_2]);"
> +		"lfs 25, 0(%[flt_2]);"
> +		"lfs 26, 0(%[flt_2]);"
> +		"lfs 27, 0(%[flt_2]);"
> +		"lfs 28, 0(%[flt_2]);"
> +		"lfs 29, 0(%[flt_2]);"
> +		"lfs 30, 0(%[flt_2]);"
> +		"lfs 31, 0(%[flt_2]);"
> +		TSUSPEND

tsuspend.

> +		"li 7, 1;"
> +		"stw 7, 0(%[cptr1]);"
> +		TRESUME

tresume.

> +		"b .;"
> +
> +		TEND

...

> +		"li 0, 0;"
> +		"ori %[res], 0, 0;"
> +		"b 3f;"
> +
> +		/* Transaction abort handler */
> +		"2: ;"
> +		"li 0, 1;"
> +		"ori %[res], 0, 0;"
> +		"mfspr %[texasr], %[sprn_texasr];"
> +
> +		"3: ;"
> +		: [res] "=r" (result), [texasr] "=r" (texasr)
> +		: [gpr_1]"i"(GPR_1), [gpr_2]"i"(GPR_2),
> +		[sprn_texasr] "i" (SPRN_TEXASR), [flt_1] "r" (&a),

Thanks for actually passing through texasr like this (as opposed to
simply hardcoding it), made this easier to read.

> +		[flt_2] "r" (&b), [cptr1] "r" (&cptr[1])
> +		: "memory", "r7", "r8", "r9", "r10",
> +		"r11", "r12", "r13", "r14", "r15", "r16",
> +		"r17", "r18", "r19", "r20", "r21", "r22",
> +		"r23", "r24", "r25", "r26", "r27", "r28",
> +		"r29", "r30", "r31"
> +		);
> +
> +	if (result) {
> +		if (!cptr[0])
> +			goto trans;
> +
> +		shmdt((void *)cptr);
> +		store_gpr(gpr_buf);
> +		store_fpr(fpr_buf);
> +
> +		if (validate_gpr(gpr_buf, GPR_3))
> +			exit(1);
> +
> +		if (validate_fpr_float(fpr_buf, c))
> +			exit(1);
> +
> +		exit(0);
> +	}
> +	shmdt((void *)cptr);
> +	exit(1);
> +}
> +
> +int trace_tm_gpr(pid_t child)
> +{
> +	unsigned long gpr[18];
> +	unsigned long fpr[32];
> +	int ret;
> +
> +	ret = start_trace(child);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	ret = show_gpr(child, gpr);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	ret = validate_gpr(gpr, GPR_2);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	ret = show_fpr(child, fpr);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	ret = validate_fpr(fpr, FPR_2_REP);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	ret = show_ckpt_fpr(child, fpr);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	ret = validate_fpr(fpr, FPR_1_REP);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	ret = show_ckpt_gpr(child, gpr);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	ret = validate_gpr(gpr, GPR_1);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	ret = write_ckpt_gpr(child, GPR_3);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	ret = write_ckpt_fpr(child, FPR_3_REP);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	pptr[0] = 1;
> +	ret = stop_trace(child);
> +	if (ret)
> +		return TEST_FAIL;
> +
> +	return TEST_PASS;

I'll repeat this somewhere else perhaps as it seems to be a theme, it
might be wise to use the TEST_FAIL(x) macro from utils.h as it will
give information to more quickly narrow down where the test failed.

> +}
> +
> +int ptrace_tm_gpr(void)
> +{
> +	pid_t pid;
> +	int ret, status;
> +
> +	SKIP_IF(!((long)get_auxv_entry(AT_HWCAP2) &
> PPC_FEATURE2_HTM));

Theres a function (have_htm()) in tm/tm.h that might be nice to move
more generally which does this... 

> +	shm_id = shmget(IPC_PRIVATE, sizeof(int) * 2,
> 0777|IPC_CREAT);
> +	pid = fork();
> +	if (pid < 0) {
> +		perror("fork() failed");
> +		return TEST_FAIL;
> +	}
> +	if (pid == 0)
> +		tm_gpr();
> +
> +	if (pid) {
> +		pptr = (unsigned long *)shmat(shm_id, NULL, 0);
> +
> +		while (!pptr[1]);
                    asm volatile("" : : : "memory");

See: Documentation/volatile-considered-harmful.txt also in some
selftests I wrote I had exactly what you had and just declaring
volatile didn't *work* [do that I thought it would which it seems is
what you want here too]!

> +			kill(pid, SIGTERM);
> +			return TEST_FAIL;
> +		}
> +
> +		shmdt((void *)pptr);
> +
> +		ret = wait(&status);
> +		shmctl(shm_id, IPC_RMID, NULL);
> +		if (ret != pid) {
> +			printf("Child's exit status not
> captured\n");
> +			return TEST_FAIL;
> +		}
> +
> +		if (WIFEXITED(status)) {
> +			if (WEXITSTATUS(status))
> +				return TEST_FAIL;
> +		}
> +		return TEST_PASS;

return (WIFEXITED(status) && WEXITSTATUS(status)) ? TEST_FAIL :
TEST_PASS;

> +	}
> +	return TEST_PASS;
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +	return test_harness(ptrace_tm_gpr, "ptrace_tm_gpr");
> +}