[Patch 2/6] Add HARDWARE_WATCHPOINTS definitions and support code.

From: David Daney
Date: Mon Apr 21 2008 - 20:11:10 EST

This patch adds arch/mips/kernel/watch.c which contains support code for
manipulating the watch registers. It also adds the needed fields to the
thread_struct and thread_info. The cpu_info structure is augmented to contain the characteristics of the watch registers.


Signed-off-by: David Daney <ddaney@xxxxxxxxxx>
---
arch/mips/kernel/Makefile | 1 +
arch/mips/kernel/watch.c | 177 ++++++++++++++++++++++++++++++++++++++++
include/asm-mips/cpu-info.h | 5 +
include/asm-mips/processor.h | 29 +++++++
include/asm-mips/thread_info.h | 2 +
include/asm-mips/watch.h | 29 +++++++
6 files changed, 243 insertions(+), 0 deletions(-)
create mode 100644 arch/mips/kernel/watch.c
create mode 100644 include/asm-mips/watch.h

diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 938be3a..5b1e017 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -72,6 +72,7 @@ obj-$(CONFIG_MIPS32_O32) += binfmt_elfo32.o scall64-o32.o

obj-$(CONFIG_KGDB) += gdb-low.o gdb-stub.o
obj-$(CONFIG_PROC_FS) += proc.o
+obj-$(CONFIG_HARDWARE_WATCHPOINTS) += watch.o

obj-$(CONFIG_64BIT) += cpu-bugs64.o

diff --git a/arch/mips/kernel/watch.c b/arch/mips/kernel/watch.c
new file mode 100644
index 0000000..6217682
--- /dev/null
+++ b/arch/mips/kernel/watch.c
@@ -0,0 +1,177 @@
+/*
+ * 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) 2008 David Daney
+ */
+
+#include <linux/sched.h>
+
+#include <asm/watch.h>
+
+void mips_install_watch_registers()
+{
+ struct mips32_watch_reg_state *watches = &current->thread.watch.mips32;
+ switch (current_cpu_data.watch_reg_count) {
+ default:
+ BUG();
+ case 8:
+ write_c0_watchlo7(watches->watchlo[7]);
+ /* Write 1 to the I, R, and W bits to clear them. */
+ write_c0_watchhi7(watches->watchhi[7] | 7);
+ case 7:
+ write_c0_watchlo6(watches->watchlo[6]);
+ write_c0_watchhi6(watches->watchhi[6] | 7);
+ case 6:
+ write_c0_watchlo5(watches->watchlo[5]);
+ write_c0_watchhi5(watches->watchhi[5] | 7);
+ case 5:
+ write_c0_watchlo4(watches->watchlo[4]);
+ write_c0_watchhi4(watches->watchhi[4] | 7);
+ case 4:
+ write_c0_watchlo3(watches->watchlo[3]);
+ write_c0_watchhi3(watches->watchhi[3] | 7);
+ case 3:
+ write_c0_watchlo2(watches->watchlo[2]);
+ write_c0_watchhi2(watches->watchhi[2] | 7);
+ case 2:
+ write_c0_watchlo1(watches->watchlo[1]);
+ write_c0_watchhi1(watches->watchhi[1] | 7);
+ case 1:
+ write_c0_watchlo0(watches->watchlo[0]);
+ write_c0_watchhi0(watches->watchhi[0] | 7);
+ }
+}
+
+/*
+ * Read back the watchhi registers so the user space debugger has
+ * access to the I, R, and W bits.
+ */
+void mips_read_watch_registers()
+{
+ struct mips32_watch_reg_state *watches = &current->thread.watch.mips32;
+ switch (current_cpu_data.watch_reg_count) {
+ default:
+ BUG();
+ case 8:
+ watches->watchhi[7] = read_c0_watchhi7();
+ case 7:
+ watches->watchhi[6] = read_c0_watchhi6();
+ case 6:
+ watches->watchhi[5] = read_c0_watchhi5();
+ case 5:
+ watches->watchhi[4] = read_c0_watchhi4();
+ case 4:
+ watches->watchhi[3] = read_c0_watchhi3();
+ case 3:
+ watches->watchhi[2] = read_c0_watchhi2();
+ case 2:
+ watches->watchhi[1] = read_c0_watchhi1();
+ case 1:
+ watches->watchhi[0] = read_c0_watchhi0();
+ }
+}
+
+void mips_clear_watch_registers()
+{
+ switch (current_cpu_data.watch_reg_count) {
+ default:
+ BUG();
+ case 8:
+ write_c0_watchlo7(0);
+ case 7:
+ write_c0_watchlo6(0);
+ case 6:
+ write_c0_watchlo5(0);
+ case 5:
+ write_c0_watchlo4(0);
+ case 4:
+ write_c0_watchlo3(0);
+ case 3:
+ write_c0_watchlo2(0);
+ case 2:
+ write_c0_watchlo1(0);
+ case 1:
+ write_c0_watchlo0(0);
+ }
+}
+
+__init void mips_probe_watch_registers(struct cpuinfo_mips *c)
+{
+ unsigned int t;
+
+ if ((c->options & MIPS_CPU_WATCH) == 0)
+ return;
+ /*
+ * Check which of the I,R and W bits are supported, then
+ * disable the register.
+ */
+ write_c0_watchlo0(7);
+ t = read_c0_watchlo0();
+ write_c0_watchlo0(0);
+ c->watch_reg_irw = t & 7;
+
+ t = read_c0_watchhi0();
+ write_c0_watchhi0(t | 0xff8);
+ t = read_c0_watchhi0();
+ c->watch_reg_count = 1;
+ c->watch_reg_mask = t & 0xff8;
+ if ((t & 0x80000000) == 0)
+ return;
+
+ t = read_c0_watchhi1();
+ write_c0_watchhi1(t | 0xff8);
+ t = read_c0_watchhi1();
+ c->watch_reg_count = 2;
+ /* Calculate the smallest common mask. */
+ c->watch_reg_mask &= t;
+ if ((t & 0x80000000) == 0)
+ return;
+
+ t = read_c0_watchhi2();
+ write_c0_watchhi2(t | 0xff8);
+ t = read_c0_watchhi2();
+ c->watch_reg_count = 3;
+ c->watch_reg_mask &= t;
+ if ((t & 0x80000000) == 0)
+ return;
+
+ t = read_c0_watchhi3();
+ write_c0_watchhi3(t | 0xff8);
+ t = read_c0_watchhi3();
+ c->watch_reg_count = 4;
+ c->watch_reg_mask &= t;
+ if ((t & 0x80000000) == 0)
+ return;
+
+ t = read_c0_watchhi4();
+ write_c0_watchhi4(t | 0xff8);
+ t = read_c0_watchhi4();
+ c->watch_reg_count = 5;
+ c->watch_reg_mask &= t;
+ if ((t & 0x80000000) == 0)
+ return;
+
+ t = read_c0_watchhi5();
+ write_c0_watchhi5(t | 0xff8);
+ t = read_c0_watchhi5();
+ c->watch_reg_count = 6;
+ c->watch_reg_mask &= t;
+ if ((t & 0x80000000) == 0)
+ return;
+
+ t = read_c0_watchhi6();
+ write_c0_watchhi6(t | 0xff8);
+ t = read_c0_watchhi6();
+ c->watch_reg_count = 7;
+ c->watch_reg_mask &= t;
+ if ((t & 0x80000000) == 0)
+ return;
+
+ t = read_c0_watchhi7();
+ write_c0_watchhi7(t | 0xff8);
+ t = read_c0_watchhi7();
+ c->watch_reg_count = 8;
+ c->watch_reg_mask &= t;
+}
diff --git a/include/asm-mips/cpu-info.h b/include/asm-mips/cpu-info.h
index 0c5a358..7d3a093 100644
--- a/include/asm-mips/cpu-info.h
+++ b/include/asm-mips/cpu-info.h
@@ -49,6 +49,11 @@ struct cpuinfo_mips {
unsigned int fpu_id;
unsigned int cputype;
int isa_level;
+#if defined(CONFIG_HARDWARE_WATCHPOINTS)
+ unsigned int watch_reg_count;
+ unsigned int watch_reg_mask;
+ unsigned int watch_reg_irw;
+#endif
int tlbsize;
struct cache_desc icache; /* Primary I-cache */
struct cache_desc dcache; /* Primary D or combined I/D cache */
diff --git a/include/asm-mips/processor.h b/include/asm-mips/processor.h
index 58cbac5..423e04d 100644
--- a/include/asm-mips/processor.h
+++ b/include/asm-mips/processor.h
@@ -105,6 +105,26 @@ struct mips_dsp_state {
{0,} \
}

+#ifdef CONFIG_HARDWARE_WATCHPOINTS
+
+#define NUM_WATCH_REGS 8
+
+struct mips32_watch_reg_state {
+ __u32 watchlo[NUM_WATCH_REGS];
+ __u32 watchhi[NUM_WATCH_REGS];
+};
+
+union mips_watch_reg_state {
+ struct mips32_watch_reg_state mips32;
+};
+
+#define INIT_WATCH .watch = {{{0,},},}
+
+#define OPTIONAL_INIT_WATCH INIT_WATCH,
+#else
+#define OPTIONAL_INIT_WATCH
+#endif
+
typedef struct {
unsigned long seg;
} mm_segment_t;
@@ -137,6 +157,11 @@ struct thread_struct {
/* Saved state of the DSP ASE, if available. */
struct mips_dsp_state dsp;

+#ifdef CONFIG_HARDWARE_WATCHPOINTS
+ /* Saved watch register state, if available. */
+ union mips_watch_reg_state watch;
+#endif
+
/* Other stuff associated with the thread. */
unsigned long cp0_badvaddr; /* Last user fault */
unsigned long cp0_baduaddr; /* Last kernel fault accessing USEG */
@@ -193,6 +218,10 @@ struct thread_struct {
.dspcontrol = 0, \
}, \
/* \
+ * saved watch register stuff \
+ */ \
+ OPTIONAL_INIT_WATCH \
+ /* \
* Other stuff associated with the process \
*/ \
.cp0_badvaddr = 0, \
diff --git a/include/asm-mips/thread_info.h b/include/asm-mips/thread_info.h
index b2772df..e31de4b 100644
--- a/include/asm-mips/thread_info.h
+++ b/include/asm-mips/thread_info.h
@@ -122,6 +122,7 @@ register struct thread_info *__current_thread_info __asm__("$28");
#define TIF_32BIT_REGS 22 /* also implies 16/32 fprs */
#define TIF_32BIT_ADDR 23 /* 32-bit address space (o32/n32) */
#define TIF_FPUBOUND 24 /* thread bound to FPU-full CPU set */
+#define TIF_LOAD_WATCH 25 /* If set, load watch registers */
#define TIF_SYSCALL_TRACE 31 /* syscall trace active */

#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE)
@@ -138,6 +139,7 @@ register struct thread_info *__current_thread_info __asm__("$28");
#define _TIF_32BIT_REGS (1<<TIF_32BIT_REGS)
#define _TIF_32BIT_ADDR (1<<TIF_32BIT_ADDR)
#define _TIF_FPUBOUND (1<<TIF_FPUBOUND)
+#define _TIF_LOAD_WATCH (1<<TIF_LOAD_WATCH)

/* work to do on interrupt/exception return */
#define _TIF_WORK_MASK (0x0000ffef & ~_TIF_SECCOMP)
diff --git a/include/asm-mips/watch.h b/include/asm-mips/watch.h
new file mode 100644
index 0000000..72607be
--- /dev/null
+++ b/include/asm-mips/watch.h
@@ -0,0 +1,29 @@
+/*
+ * 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) 2008 David Daney
+ */
+#ifndef _ASM_WATCH_H
+#define _ASM_WATCH_H
+
+#include <asm/mipsregs.h>
+
+#ifdef CONFIG_HARDWARE_WATCHPOINTS
+void mips_install_watch_registers(void);
+void mips_read_watch_registers(void);
+void mips_clear_watch_registers(void);
+void mips_probe_watch_registers(struct cpuinfo_mips *c);
+
+#define __restore_watch() do { \
+ if (unlikely(current_thread_info()->flags & _TIF_LOAD_WATCH)) { \
+ mips_install_watch_registers(); \
+ } \
+} while (0)
+
+#else
+#define __restore_watch() do {} while (0)
+#endif
+
+#endif /* _ASM_WATCH_H */
--
1.5.5

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