MIPS: kernel: mips-r2-to-r6-emul: Add R2 emulator for MIPS R6

MIPS R6 removed quite a few R2 instructions. However, there is plenty of <R6 userland code so we add an in-kernel emulator so we can still be able to execute all R2 userland out there. The emulator comes with a handy debugfs under /mips/ directory (r2-emul-stats) to provide some basic statistics of the instructions that are being emulated. Below are some statistics from booting a minimal buildroot image: Instruction Total BDslot ------------------------------ movs 236969 0 hilo 56686 0 muls 55279 0 divs 10941 0 dsps 0 0 bops 1 0 traps 0 0 fpus 0 0 loads 214981 17 stores 103364 0 llsc 56898 0 dsemul 150418 0 jr 370158 bltzl 43 bgezl 1594 bltzll 0 bgezll 0 bltzal 39 bgezal 39 beql 14503 bnel 138741 blezl 0 bgtzl 3988 Signed-off-by: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com> Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
libos-nuse · Feb 17, 2015 · b0a668f · b0a668f
1 parent b55b9e2
commit b0a668f
Show file tree

Hide file tree

Showing 8 changed files with 2,518 additions and 5 deletions.
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
@@ -2063,6 +2063,19 @@ config MIPS_MT_FPAFF
  default y
  depends on MIPS_MT_SMP
 
+config MIPSR2_TO_R6_EMULATOR
+ bool "MIPS R2-to-R6 emulator"
+ depends on CPU_MIPSR6 && !SMP
+ default y
+ help
+ Choose this option if you want to run non-R6 MIPS userland code.
+ Even if you say 'Y' here, the emulator will still be disabled by
+ default. You can enable it using the 'mipsr2emul' kernel option.
+ The only reason this is a build-time option is to save ~14K from the
+ final kernel image.
+comment "MIPS R2-to-R6 emulator is only available for UP kernels"
+ depends on SMP && CPU_MIPSR6
+
 config MIPS_VPE_LOADER
  bool "VPE loader support."
  depends on SYS_SUPPORTS_MULTITHREADING && MODULES

diff --git a/arch/mips/include/asm/branch.h b/arch/mips/include/asm/branch.h
@@ -13,9 +13,6 @@
 #include <asm/ptrace.h>
 #include <asm/inst.h>
 
-static int mipsr2_emulation = 0;
-#define NO_R6EMU (cpu_has_mips_r6 && !mipsr2_emulation)
-
 extern int __isa_exception_epc(struct pt_regs *regs);
 extern int __compute_return_epc(struct pt_regs *regs);
 extern int __compute_return_epc_for_insn(struct pt_regs *regs,

diff --git a/arch/mips/include/asm/mips-r2-to-r6-emul.h b/arch/mips/include/asm/mips-r2-to-r6-emul.h
@@ -0,0 +1,96 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License. See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (c) 2014 Imagination Technologies Ltd.
+ * Author: Markos Chandras <markos.chandras@imgtec.com>
+ */
+
+#ifndef __ASM_MIPS_R2_TO_R6_EMUL_H
+#define __ASM_MIPS_R2_TO_R6_EMUL_H
+
+struct mips_r2_emulator_stats {
+ u64 movs;
+ u64 hilo;
+ u64 muls;
+ u64 divs;
+ u64 dsps;
+ u64 bops;
+ u64 traps;
+ u64 fpus;
+ u64 loads;
+ u64 stores;
+ u64 llsc;
+ u64 dsemul;
+};
+
+struct mips_r2br_emulator_stats {
+ u64 jrs;
+ u64 bltzl;
+ u64 bgezl;
+ u64 bltzll;
+ u64 bgezll;
+ u64 bltzall;
+ u64 bgezall;
+ u64 bltzal;
+ u64 bgezal;
+ u64 beql;
+ u64 bnel;
+ u64 blezl;
+ u64 bgtzl;
+};
+
+#ifdef CONFIG_DEBUG_FS
+
+#define MIPS_R2_STATS(M) \
+do { \
+ u32 nir; \
+ int err; \
+ \
+ preempt_disable(); \
+ __this_cpu_inc(mipsr2emustats.M); \
+ err = __get_user(nir, (u32 __user *)regs->cp0_epc); \
+ if (!err) { \
+ if (nir == BREAK_MATH) \
+ __this_cpu_inc(mipsr2bdemustats.M); \
+ } \
+ preempt_enable(); \
+} while (0)
+
+#define MIPS_R2BR_STATS(M) \
+do { \
+ preempt_disable(); \
+ __this_cpu_inc(mipsr2bremustats.M); \
+ preempt_enable(); \
+} while (0)
+
+#else
+
+#define MIPS_R2_STATS(M) do { } while (0)
+#define MIPS_R2BR_STATS(M) do { } while (0)
+
+#endif /* CONFIG_DEBUG_FS */
+
+struct r2_decoder_table {
+ u32 mask;
+ u32 code;
+ int (*func)(struct pt_regs *regs, u32 inst);
+};
+
+
+extern void do_trap_or_bp(struct pt_regs *regs, unsigned int code,
+ const char *str);
+
+#ifndef CONFIG_MIPSR2_TO_R6_EMULATOR
+static int mipsr2_emulation;
+static __maybe_unused int mipsr2_decoder(struct pt_regs *regs, u32 inst) { return 0; };
+#else
+/* MIPS R2 Emulator ON/OFF */
+extern int mipsr2_emulation;
+extern int mipsr2_decoder(struct pt_regs *regs, u32 inst);
+#endif /* CONFIG_MIPSR2_TO_R6_EMULATOR */
+
+#define NO_R6EMU (cpu_has_mips_r6 && !mipsr2_emulation)
+
+#endif /* __ASM_MIPS_R2_TO_R6_EMUL_H */
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
@@ -90,6 +90,7 @@ obj-$(CONFIG_EARLY_PRINTK) += early_printk.o
 obj-$(CONFIG_EARLY_PRINTK_8250) += early_printk_8250.o
 obj-$(CONFIG_SPINLOCK_TEST) += spinlock_test.o
 obj-$(CONFIG_MIPS_MACHINE) += mips_machine.o
+obj-$(CONFIG_MIPSR2_TO_R6_EMULATOR) += mips-r2-to-r6-emul.o
 
 CFLAGS_cpu-bugs64.o = $(shell if $(CC) $(KBUILD_CFLAGS) -Wa,-mdaddi -c -o /dev/null -x c /dev/null >/dev/null 2>&1; then echo "-DHAVE_AS_SET_DADDI"; fi)
 

diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
@@ -16,6 +16,7 @@
 #include <asm/fpu.h>
 #include <asm/fpu_emulator.h>
 #include <asm/inst.h>
+#include <asm/mips-r2-to-r6-emul.h>
 #include <asm/ptrace.h>
 #include <asm/uaccess.h>