powerpc/test_emulate_step: Enhancement to test negative scenarios

add provision to declare test is a negative scenario, verify
whether emulation fails and avoid executing it.

Signed-off-by: Balamuruhan S <bala24@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200626095158.1031507-2-bala24@linux.ibm.com

diff --git a/arch/powerpc/lib/test_emulate_step.c b/arch/powerpc/lib/test_emulate_step.c
index e25e92750416d9d5955dfa6a212a693bed3da632..31065e986ff0ce0bf09afc4e71a4cb79bc99bb9e 100644 (file)
--- a/arch/powerpc/lib/test_emulate_step.c
+++ b/arch/powerpc/lib/test_emulate_step.c
@@ -18,6 +18,7 @@
 #define IGNORE_GPR(n)  (0x1UL << (n))
 #define IGNORE_XER     (0x1UL << 32)
 #define IGNORE_CCR     (0x1UL << 33)
+#define NEGATIVE_TEST  (0x1UL << 63)
 
 #define TEST_PLD(r, base, i, pr) \
        ppc_inst_prefix(PPC_PREFIX_8LS | __PPC_PRFX_R(pr) | IMM_H(i), \
@@ -1135,8 +1136,10 @@ static struct compute_test compute_tests[] = {
 };
 
 static int __init emulate_compute_instr(struct pt_regs *regs,
-                                       struct ppc_inst instr)
+                                       struct ppc_inst instr,
+                                       bool negative)
 {
+       int analysed;
        extern s32 patch__exec_instr;
        struct instruction_op op;
 
@@ -1145,13 +1148,17 @@ static int __init emulate_compute_instr(struct pt_regs *regs,
 
        regs->nip = patch_site_addr(&patch__exec_instr);
 
-       if (analyse_instr(&op, regs, instr) != 1 ||
-           GETTYPE(op.type) != COMPUTE) {
-               pr_info("execution failed, instruction = %s\n", ppc_inst_as_str(instr));
+       analysed = analyse_instr(&op, regs, instr);
+       if (analysed != 1 || GETTYPE(op.type) != COMPUTE) {
+               if (negative)
+                       return -EFAULT;
+               pr_info("emulation failed, instruction = %s\n", ppc_inst_as_str(instr));
                return -EFAULT;
        }
-
-       emulate_update_regs(regs, &op);
+       if (analysed == 1 && negative)
+               pr_info("negative test failed, instruction = %s\n", ppc_inst_as_str(instr));
+       if (!negative)
+               emulate_update_regs(regs, &op);
        return 0;
 }
 
@@ -1189,7 +1196,7 @@ static void __init run_tests_compute(void)
        struct pt_regs *regs, exp, got;
        unsigned int i, j, k;
        struct ppc_inst instr;
-       bool ignore_gpr, ignore_xer, ignore_ccr, passed;
+       bool ignore_gpr, ignore_xer, ignore_ccr, passed, rc, negative;
 
        for (i = 0; i < ARRAY_SIZE(compute_tests); i++) {
                test = &compute_tests[i];
@@ -1203,6 +1210,7 @@ static void __init run_tests_compute(void)
                        instr = test->subtests[j].instr;
                        flags = test->subtests[j].flags;
                        regs = &test->subtests[j].regs;
+                       negative = flags & NEGATIVE_TEST;
                        ignore_xer = flags & IGNORE_XER;
                        ignore_ccr = flags & IGNORE_CCR;
                        passed = true;
@@ -1217,8 +1225,12 @@ static void __init run_tests_compute(void)
                        exp.msr = MSR_KERNEL;
                        got.msr = MSR_KERNEL;
 
-                       if (emulate_compute_instr(&got, instr) ||
-                           execute_compute_instr(&exp, instr)) {
+                       rc = emulate_compute_instr(&got, instr, negative) != 0;
+                       if (negative) {
+                               /* skip executing instruction */
+                               passed = rc;
+                               goto print;
+                       } else if (rc || execute_compute_instr(&exp, instr)) {
                                passed = false;
                                goto print;
                        }