powerpc: Keep track of emulated instructions

If CONFIG_PPC_EMULATED_STATS is enabled, make available counters for the
various classes of emulated instructions under
/sys/kernel/debug/powerpc/emulated_instructions/ (assumed debugfs is mounted on
/sys/kernel/debug).  Optionally (controlled by
/sys/kernel/debug/powerpc/emulated_instructions/do_warn), rate-limited warnings
can be printed to the console when instructions are emulated.

Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

1 files changed, 94 insertions, 2 deletions

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 678fbff0d206..6a5b2b731f43 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -33,7 +33,9 @@
 #include <linux/backlight.h>
 #include <linux/bug.h>
 #include <linux/kdebug.h>
+#include <linux/debugfs.h>
 
+#include <asm/emulated_ops.h>
 #include <asm/pgtable.h>
 #include <asm/uaccess.h>
 #include <asm/system.h>
@@ -757,36 +759,44 @@ static int emulate_instruction(struct pt_regs *regs)
 
         /* Emulate the mfspr rD, PVR. */
         if ((instword & PPC_INST_MFSPR_PVR_MASK) == PPC_INST_MFSPR_PVR) {
+                PPC_WARN_EMULATED(mfpvr);
                 rd = (instword >> 21) & 0x1f;
                 regs->gpr[rd] = mfspr(SPRN_PVR);
                 return 0;
         }
 
         /* Emulating the dcba insn is just a no-op.  */
-        if ((instword & PPC_INST_DCBA_MASK) == PPC_INST_DCBA)
+        if ((instword & PPC_INST_DCBA_MASK) == PPC_INST_DCBA) {
+                PPC_WARN_EMULATED(dcba);
                 return 0;
+        }
 
         /* Emulate the mcrxr insn.  */
         if ((instword & PPC_INST_MCRXR_MASK) == PPC_INST_MCRXR) {
                 int shift = (instword >> 21) & 0x1c;
                 unsigned long msk = 0xf0000000UL >> shift;
 
+                PPC_WARN_EMULATED(mcrxr);
                 regs->ccr = (regs->ccr & ~msk) | ((regs->xer >> shift) & msk);
                 regs->xer &= ~0xf0000000UL;
                 return 0;
         }
 
         /* Emulate load/store string insn. */
-        if ((instword & PPC_INST_STRING_GEN_MASK) == PPC_INST_STRING)
+        if ((instword & PPC_INST_STRING_GEN_MASK) == PPC_INST_STRING) {
+                PPC_WARN_EMULATED(string);
                 return emulate_string_inst(regs, instword);
+        }
 
         /* Emulate the popcntb (Population Count Bytes) instruction. */
         if ((instword & PPC_INST_POPCNTB_MASK) == PPC_INST_POPCNTB) {
+                PPC_WARN_EMULATED(popcntb);
                 return emulate_popcntb_inst(regs, instword);
         }
 
         /* Emulate isel (Integer Select) instruction */
         if ((instword & PPC_INST_ISEL_MASK) == PPC_INST_ISEL) {
+                PPC_WARN_EMULATED(isel);
                 return emulate_isel(regs, instword);
         }
 
@@ -984,6 +994,8 @@ void SoftwareEmulation(struct pt_regs *regs)
 
 #ifdef CONFIG_MATH_EMULATION
         errcode = do_mathemu(regs);
+        if (errcode >= 0)
+                PPC_WARN_EMULATED(math);
 
         switch (errcode) {
         case 0:
@@ -1005,6 +1017,9 @@ void SoftwareEmulation(struct pt_regs *regs)
 
 #elif defined(CONFIG_8XX_MINIMAL_FPEMU)
         errcode = Soft_emulate_8xx(regs);
+        if (errcode >= 0)
+                PPC_WARN_EMULATED(8xx);
+
         switch (errcode) {
         case 0:
                 emulate_single_step(regs);
@@ -1088,6 +1103,7 @@ void altivec_assist_exception(struct pt_regs *regs)
 
         flush_altivec_to_thread(current);
 
+        PPC_WARN_EMULATED(altivec);
         err = emulate_altivec(regs);
         if (err == 0) {
                 regs->nip += 4;         /* skip emulated instruction */
@@ -1286,3 +1302,79 @@ void kernel_bad_stack(struct pt_regs *regs)
 void __init trap_init(void)
 {
 }
+
+
+#ifdef CONFIG_PPC_EMULATED_STATS
+
+#define WARN_EMULATED_SETUP(type)       .type = { .name = #type }
+
+struct ppc_emulated ppc_emulated = {
+#ifdef CONFIG_ALTIVEC
+        WARN_EMULATED_SETUP(altivec),
+#endif
+        WARN_EMULATED_SETUP(dcba),
+        WARN_EMULATED_SETUP(dcbz),
+        WARN_EMULATED_SETUP(fp_pair),
+        WARN_EMULATED_SETUP(isel),
+        WARN_EMULATED_SETUP(mcrxr),
+        WARN_EMULATED_SETUP(mfpvr),
+        WARN_EMULATED_SETUP(multiple),
+        WARN_EMULATED_SETUP(popcntb),
+        WARN_EMULATED_SETUP(spe),
+        WARN_EMULATED_SETUP(string),
+        WARN_EMULATED_SETUP(unaligned),
+#ifdef CONFIG_MATH_EMULATION
+        WARN_EMULATED_SETUP(math),
+#elif defined(CONFIG_8XX_MINIMAL_FPEMU)
+        WARN_EMULATED_SETUP(8xx),
+#endif
+#ifdef CONFIG_VSX
+        WARN_EMULATED_SETUP(vsx),
+#endif
+};
+
+u32 ppc_warn_emulated;
+
+void ppc_warn_emulated_print(const char *type)
+{
+        if (printk_ratelimit())
+                pr_warning("%s used emulated %s instruction\n", current->comm,
+                           type);
+}
+
+static int __init ppc_warn_emulated_init(void)
+{
+        struct dentry *dir, *d;
+        unsigned int i;
+        struct ppc_emulated_entry *entries = (void *)&ppc_emulated;
+
+        if (!powerpc_debugfs_root)
+                return -ENODEV;
+
+        dir = debugfs_create_dir("emulated_instructions",
+                                 powerpc_debugfs_root);
+        if (!dir)
+                return -ENOMEM;
+
+        d = debugfs_create_u32("do_warn", S_IRUGO | S_IWUSR, dir,
+                               &ppc_warn_emulated);
+        if (!d)
+                goto fail;
+
+        for (i = 0; i < sizeof(ppc_emulated)/sizeof(*entries); i++) {
+                d = debugfs_create_u32(entries[i].name, S_IRUGO | S_IWUSR, dir,
+                                       (u32 *)&entries[i].val.counter);
+                if (!d)
+                        goto fail;
+        }
+
+        return 0;
+
+fail:
+        debugfs_remove_recursive(dir);
+        return -ENOMEM;
+}
+
+device_initcall(ppc_warn_emulated_init);
+
+#endif /* CONFIG_PPC_EMULATED_STATS */