path: root/arch/powerpc/lib/test_emulate_step.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Simple sanity tests for instruction emulation infrastructure.
 *
 * Copyright IBM Corp. 2016
 */

#define pr_fmt(fmt) "emulate_step_test: " fmt

#include <linux/ptrace.h>
#include <asm/sstep.h>
#include <asm/ppc-opcode.h>
#include <asm/code-patching.h>
#include <asm/inst.h>

#define MAX_SUBTESTS	16

#define IGNORE_GPR(n)	(0x1UL << (n))
#define IGNORE_XER	(0x1UL << 32)
#define IGNORE_CCR	(0x1UL << 33)

static void __init init_pt_regs(struct pt_regs *regs)
{
	static unsigned long msr;
	static bool msr_cached;

	memset(regs, 0, sizeof(struct pt_regs));

	if (likely(msr_cached)) {
		regs->msr = msr;
		return;
	}

	asm volatile("mfmsr %0" : "=r"(regs->msr));

	regs->msr |= MSR_FP;
	regs->msr |= MSR_VEC;
	regs->msr |= MSR_VSX;

	msr = regs->msr;
	msr_cached = true;
}

static void __init show_result(char *mnemonic, char *result)
{
	pr_info("%-14s : %s\n", mnemonic, result);
}

static void __init show_result_with_descr(char *mnemonic, char *descr,
					  char *result)
{
	pr_info("%-14s : %-50s %s\n", mnemonic, descr, result);
}

static void __init test_ld(void)
{
	struct pt_regs regs;
	unsigned long a = 0x23;
	int stepped = -1;

	init_pt_regs(&regs);
	regs.gpr[3] = (unsigned long) &a;

	/* ld r5, 0(r3) */
	stepped = emulate_step(&regs, ppc_inst(PPC_RAW_LD(5, 3, 0)));

	if (stepped == 1 && regs.gpr[5] == a)
		show_result("ld", "PASS");
	else
		show_result("ld", "FAIL");
}

static void __init test_lwz(void)
{
	struct pt_regs regs;
	unsigned int a = 0x4545;
	int stepped = -1;

	init_pt_regs(&regs);
	regs.gpr[3] = (unsigned long) &a;

	/* lwz r5, 0(r3) */
	stepped = emulate_step(&regs, ppc_inst(PPC_RAW_LWZ(5, 3, 0)));

	if (stepped == 1 && regs.gpr[5] == a)
		show_result("lwz", "PASS");
	else
		show_result("lwz", "FAIL");
}

static void __init test_lwzx(void)
{
	struct pt_regs regs;
	unsigned int a[3] = {0x0, 0x0, 0x1234};
	int stepped = -1;

	init_pt_regs(&regs);
	regs.gpr[3] = (unsigned long) a;
	regs.gpr[4] = 8;
	regs.gpr[5] = 0x8765;

	/* lwzx r5, r3, r4 */
	stepped = emulate_step(&regs, ppc_inst(PPC_RAW_LWZX(5, 3, 4)));
	if (stepped == 1 && regs.gpr[5] == a[2])
		show_result("lwzx", "PASS");
	else
		show_result("lwzx", "FAIL");
}

static void __init test_std(void)
{
	struct pt_regs regs;
	unsigned long a = 0x1234;
	int stepped = -1;

	init_pt_regs(&regs);
	regs.gpr[3] = (unsigned long) &a;
	regs.gpr[5] = 0x5678;

	/* std r5, 0(r3) */
	stepped = emulate_step(&regs, ppc_inst(PPC_RAW_STD(5, 3, 0)));
	if (stepped == 1 && regs.gpr[5] == a)
		show_result("std", "PASS");
	else
		show_result("std", "FAIL");
}

static void __init test_ldarx_stdcx(void)
{
	struct pt_regs regs;
	unsigned long a = 0x1234;
	int stepped = -1;
	unsigned long cr0_eq = 0x1 << 29; /* eq bit of CR0 */

	init_pt_regs(&regs);
	asm volatile("mfcr %0" : "=r"(regs.ccr));


	/*** ldarx ***/

	regs.gpr[3] = (unsigned long) &a;
	regs.gpr[4] = 0;
	regs.gpr[5] = 0x5678;

	/* ldarx r5, r3, r4, 0 */
	stepped = emulate_step(&regs, ppc_inst(PPC_RAW_LDARX(5, 3, 4, 0)));

	/*
	 * Don't touch 'a' here. Touching 'a' can do Load/store
	 * of 'a' which result in failure of subsequent stdcx.
	 * Instead, use hardcoded value for comparison.
	 */
	if (stepped <= 0 || regs.gpr[5] != 0x1234) {
		show_result("ldarx / stdcx.", "FAIL (ldarx)");
		return;
	}


	/*** stdcx. ***/

	regs.gpr[5] = 0x9ABC;

	/* stdcx. r5, r3, r4 */
	stepped = emulate_step(&regs, ppc_inst(PPC_RAW_STDCX(5, 3, 4)));

	/*
	 * Two possible scenarios that indicates successful emulation
	 * of stdcx. :
	 *  1. Reservation is active and store is performed. In this
	 *     case cr0.eq bit will be set to 1.
	 *  2. Reservation is not active and store is not performed.
	 *     In this case cr0.eq bit will be set to 0.
	 */
	if (stepped == 1 && ((regs.gpr[5] == a && (regs.ccr & cr0_eq))
			|| (regs.gpr[5] != a && !(regs.ccr & cr0_eq))))
		show_result("ldarx / stdcx.", "PASS");
	else
		show_result("ldarx / stdcx.", "FAIL (stdcx.)");
}

#ifdef CONFIG_PPC_FPU
static void __init test_lfsx_stfsx(void)
{
	struct pt_regs regs;
	union {
		float a;
		int b;
	} c;
	int cached_b;
	int stepped = -1;

	init_pt_regs(&regs);


	/*** lfsx ***/

	c.a = 123.45;
	cached_b = c.b;

	regs.gpr[3] = (unsigned long) &c.a;
	regs.gpr[4] = 0;

	/* lfsx frt1