Patchwork [v3] powerpc: Keep track of emulated instructions if debugfs is enabled

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Submitter Geert Uytterhoeven
Date May 8, 2009, 2:15 p.m.
Message ID <alpine.LRH.2.00.0905081611130.7964@vixen.sonytel.be>
Download mbox | patch
Permalink /patch/27015/
State Superseded, archived
Delegated to: Benjamin Herrenschmidt
Headers show

Comments

Geert Uytterhoeven - May 8, 2009, 2:15 p.m.
Counters for the various classes of emulated instructions are available 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>
---
Tested on ppc64 (ps3) and ppc32 (sequoia) using mfpvr.

v3:
  - add generic unaligned
  - switch from sysfs + sysctl to debugfs. All virtual files now show up under
    /sys/kernel/debug/powerpc/emulated_instructions (assumed debugfs mounted on
    /sys/kernel/debug)
  - enable the printing of rate-limited warnings by writing a non-zero value to
    /sys/kernel/debug/powerpc/emulated_instructions/do_warn
  - switch from per-CPU to system-wide counters
  - always use 32-bit counters (was 64-bit on ppc64)
  - counters are writable, i.e. can be reset (by root)

v2:
  - arch/powerpc/kernel/sysfs.c is now compiled on ppc32, so we can provide
    counters in sysfs on ppc32, too,
  - WARN_EMULATED() is a no-op if CONFIG_SYSCTL is disabled,
  - Add warnings for altivec,
  - Add warnings for recently introduced emulation of vsx and isel
    instructions.

 arch/powerpc/include/asm/emulated_ops.h |   73 +++++++++++++++++++++++
 arch/powerpc/kernel/align.c             |   20 +++++-
 arch/powerpc/kernel/traps.c             |   96 ++++++++++++++++++++++++++++++-
 3 files changed, 183 insertions(+), 6 deletions(-)
 create mode 100644 arch/powerpc/include/asm/emulated_ops.h
Michael Ellerman - May 11, 2009, 2:32 a.m.
On Fri, 2009-05-08 at 16:15 +0200, Geert Uytterhoeven wrote:
> Counters for the various classes of emulated instructions are available 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>
> ---
> Tested on ppc64 (ps3) and ppc32 (sequoia) using mfpvr.
> 
> v3:
>   - add generic unaligned
>   - switch from sysfs + sysctl to debugfs. All virtual files now show up under
>     /sys/kernel/debug/powerpc/emulated_instructions (assumed debugfs mounted on
>     /sys/kernel/debug)
>   - enable the printing of rate-limited warnings by writing a non-zero value to
>     /sys/kernel/debug/powerpc/emulated_instructions/do_warn
>   - switch from per-CPU to system-wide counters
>   - always use 32-bit counters (was 64-bit on ppc64)
>   - counters are writable, i.e. can be reset (by root)

Nice :)

My only query is whether it needs its own CONFIG option. Some folks
might want other DEBUG_FS things but not this?

cheers
Geert Uytterhoeven - May 11, 2009, 6:39 a.m.
On Mon, 11 May 2009, Michael Ellerman wrote:
> On Fri, 2009-05-08 at 16:15 +0200, Geert Uytterhoeven wrote:
> > Counters for the various classes of emulated instructions are available 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>
> > ---
> > Tested on ppc64 (ps3) and ppc32 (sequoia) using mfpvr.
> > 
> > v3:
> >   - add generic unaligned
> >   - switch from sysfs + sysctl to debugfs. All virtual files now show up under
> >     /sys/kernel/debug/powerpc/emulated_instructions (assumed debugfs mounted on
> >     /sys/kernel/debug)
> >   - enable the printing of rate-limited warnings by writing a non-zero value to
> >     /sys/kernel/debug/powerpc/emulated_instructions/do_warn
> >   - switch from per-CPU to system-wide counters
> >   - always use 32-bit counters (was 64-bit on ppc64)
> >   - counters are writable, i.e. can be reset (by root)
> 
> Nice :)
> 
> My only query is whether it needs its own CONFIG option. Some folks
> might want other DEBUG_FS things but not this?

That's possible. Let's see what the other folks say...

With kind regards,

Geert Uytterhoeven
Software Architect
Techsoft Centre

Technology and Software Centre Europe
The Corporate Village · Da Vincilaan 7-D1 · B-1935 Zaventem · Belgium

Phone:    +32 (0)2 700 8453
Fax:      +32 (0)2 700 8622
E-mail:   Geert.Uytterhoeven@sonycom.com
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Patch

diff --git a/arch/powerpc/include/asm/emulated_ops.h b/arch/powerpc/include/asm/emulated_ops.h
new file mode 100644
index 0000000..a1fdb0a
--- /dev/null
+++ b/arch/powerpc/include/asm/emulated_ops.h
@@ -0,0 +1,73 @@ 
+/*
+ *  Copyright 2007 Sony Corp.
+ *
+ *  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; version 2 of the License.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#ifndef _ASM_POWERPC_EMULATED_OPS_H
+#define _ASM_POWERPC_EMULATED_OPS_H
+
+#include <asm/atomic.h>
+
+
+#ifdef CONFIG_DEBUG_FS
+
+struct ppc_emulated_entry {
+	const char *name;
+	atomic_t val;
+};
+
+extern struct ppc_emulated {
+#ifdef CONFIG_ALTIVEC
+	struct ppc_emulated_entry altivec;
+#endif
+	struct ppc_emulated_entry dcba;
+	struct ppc_emulated_entry dcbz;
+	struct ppc_emulated_entry fp_pair;
+	struct ppc_emulated_entry isel;
+	struct ppc_emulated_entry mcrxr;
+	struct ppc_emulated_entry mfpvr;
+	struct ppc_emulated_entry multiple;
+	struct ppc_emulated_entry popcntb;
+	struct ppc_emulated_entry spe;
+	struct ppc_emulated_entry string;
+	struct ppc_emulated_entry unaligned;
+#ifdef CONFIG_MATH_EMULATION
+	struct ppc_emulated_entry math;
+#elif defined(CONFIG_8XX_MINIMAL_FPEMU)
+	struct ppc_emulated_entry 8xx;
+#endif
+#ifdef CONFIG_VSX
+	struct ppc_emulated_entry vsx;
+#endif
+} ppc_emulated;
+
+extern u32 ppc_warn_emulated;
+
+extern void ppc_warn_emulated_print(const char *type);
+
+#define PPC_WARN_EMULATED(type)						 \
+	do {								 \
+		atomic_inc(&ppc_emulated.type.val);			 \
+		if (ppc_warn_emulated)					 \
+			ppc_warn_emulated_print(ppc_emulated.type.name); \
+	} while (0)
+
+#else /* !CONFIG_DEBUG_FS */
+
+#define PPC_WARN_EMULATED(type)	do { } while (0)
+
+#endif /* !CONFIG_DEBUG_FS */
+
+#endif /* _ASM_POWERPC_EMULATED_OPS_H */
diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c
index 5ffcfaa..a5b632e 100644
--- a/arch/powerpc/kernel/align.c
+++ b/arch/powerpc/kernel/align.c
@@ -24,6 +24,7 @@ 
 #include <asm/system.h>
 #include <asm/cache.h>
 #include <asm/cputable.h>
+#include <asm/emulated_ops.h>
 
 struct aligninfo {
 	unsigned char len;
@@ -730,8 +731,10 @@  int fix_alignment(struct pt_regs *regs)
 	areg = dsisr & 0x1f;		/* register to update */
 
 #ifdef CONFIG_SPE
-	if ((instr >> 26) == 0x4)
+	if ((instr >> 26) == 0x4) {
+		PPC_WARN_EMULATED(spe);
 		return emulate_spe(regs, reg, instr);
+	}
 #endif
 
 	instr = (dsisr >> 10) & 0x7f;
@@ -783,23 +786,28 @@  int fix_alignment(struct pt_regs *regs)
 			flags |= SPLT;
 			nb = 8;
 		}
+		PPC_WARN_EMULATED(vsx);
 		return emulate_vsx(addr, reg, areg, regs, flags, nb);
 	}
 #endif
 	/* A size of 0 indicates an instruction we don't support, with
 	 * the exception of DCBZ which is handled as a special case here
 	 */
-	if (instr == DCBZ)
+	if (instr == DCBZ) {
+		PPC_WARN_EMULATED(dcbz);
 		return emulate_dcbz(regs, addr);
+	}
 	if (unlikely(nb == 0))
 		return 0;
 
 	/* Load/Store Multiple instructions are handled in their own
 	 * function
 	 */
-	if (flags & M)
+	if (flags & M) {
+		PPC_WARN_EMULATED(multiple);
 		return emulate_multiple(regs, addr, reg, nb,
 					flags, instr, swiz);
+	}
 
 	/* Verify the address of the operand */
 	if (unlikely(user_mode(regs) &&
@@ -816,8 +824,12 @@  int fix_alignment(struct pt_regs *regs)
 	}
 
 	/* Special case for 16-byte FP loads and stores */
-	if (nb == 16)
+	if (nb == 16) {
+		PPC_WARN_EMULATED(fp_pair);
 		return emulate_fp_pair(addr, reg, flags);
+	}
+
+	PPC_WARN_EMULATED(unaligned);
 
 	/* If we are loading, get the data from user space, else
 	 * get it from register values
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 678fbff..1e88109 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_DEBUG_FS
+
+#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_DEBUG_FS */