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Message-ID: <48C8B2C3.4050002@avtrex.com>
Date: Wed, 10 Sep 2008 22:55:15 -0700
From: David Daney <ddaney@...rex.com>
To: linux-mips@...ux-mips.org
Cc: linux-kernel@...r.kernel.org
Subject: [Patch 2/6] MIPS: Add HARDWARE_WATCHPOINTS definitions and support
code.
Add HARDWARE_WATCHPOINTS definitions and support code.
This is the main support code for the patch. Here we just add the
code, the following patches hook it up.
Signed-off-by: David Daney <ddaney@...rex.com>
---
arch/mips/kernel/Makefile | 2 +-
arch/mips/kernel/watch.c | 188 ++++++++++++++++++++++++++++++++++++++++
include/asm-mips/cpu-info.h | 6 ++
include/asm-mips/processor.h | 20 ++++
include/asm-mips/thread_info.h | 2 +
include/asm-mips/watch.h | 32 +++++++
6 files changed, 249 insertions(+), 1 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 706f939..2504f15 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -6,7 +6,7 @@ extra-y := head.o init_task.o vmlinux.lds
obj-y += cpu-probe.o branch.o entry.o genex.o irq.o process.o \
ptrace.o reset.o setup.o signal.o syscall.o \
- time.o topology.o traps.o unaligned.o
+ time.o topology.o traps.o unaligned.o watch.o
obj-$(CONFIG_CEVT_BCM1480) += cevt-bcm1480.o
obj-$(CONFIG_CEVT_R4K) += cevt-r4k.o
diff --git a/arch/mips/kernel/watch.c b/arch/mips/kernel/watch.c
new file mode 100644
index 0000000..e9c4f5d
--- /dev/null
+++ b/arch/mips/kernel/watch.c
@@ -0,0 +1,188 @@
+/*
+ * 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/processor.h>
+#include <asm/watch.h>
+
+/*
+ * Install the watch registers for the current thread. A maximum of
+ * four registers are installed although the machine may have more.
+ */
+void mips_install_watch_registers(void)
+{
+ struct mips3264_watch_reg_state *watches =
+ ¤t->thread.watch.mips3264;
+ switch (current_cpu_data.watch_reg_use_cnt) {
+ default:
+ BUG();
+ case 4:
+ write_c0_watchlo3(watches->watchlo[3]);
+ /* Write 1 to the I, R, and W bits to clear them, and
+ 1 to G so all ASIDs are trapped. */
+ write_c0_watchhi3(0x40000007 | watches->watchhi[3]);
+ case 3:
+ write_c0_watchlo2(watches->watchlo[2]);
+ write_c0_watchhi2(0x40000007 | watches->watchhi[2]);
+ case 2:
+ write_c0_watchlo1(watches->watchlo[1]);
+ write_c0_watchhi1(0x40000007 | watches->watchhi[1]);
+ case 1:
+ write_c0_watchlo0(watches->watchlo[0]);
+ write_c0_watchhi0(0x40000007 | watches->watchhi[0]);
+ }
+}
+
+/*
+ * Read back the watchhi registers so the user space debugger has
+ * access to the I, R, and W bits. A maximum of four registers are
+ * read although the machine may have more.
+ */
+void mips_read_watch_registers(void)
+{
+ struct mips3264_watch_reg_state *watches =
+ ¤t->thread.watch.mips3264;
+ switch (current_cpu_data.watch_reg_use_cnt) {
+ default:
+ BUG();
+ case 4:
+ watches->watchhi[3] = (read_c0_watchhi3() & 0x0fff);
+ case 3:
+ watches->watchhi[2] = (read_c0_watchhi2() & 0x0fff);
+ case 2:
+ watches->watchhi[1] = (read_c0_watchhi1() & 0x0fff);
+ case 1:
+ watches->watchhi[0] = (read_c0_watchhi0() & 0x0fff);
+ }
+ if (current_cpu_data.watch_reg_use_cnt == 1 &&
+ (watches->watchhi[0] & 7) == 0) {
+ /* Pathological case of release 1 architecture that
+ * doesn't set the condition bits. We assume that
+ * since we got here, the watch condition was met and
+ * signal that the conditions requested in watchlo
+ * were met. */
+ watches->watchhi[0] |= (watches->watchlo[0] & 7);
+ }
+ }
+
+/*
+ * Disable all watch registers. Although only four registers are
+ * installed, all are cleared to eliminate the possibility of endless
+ * looping in the watch handler.
+ */
+void mips_clear_watch_registers(void)
+{
+ 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_masks[0] = t & 7;
+
+ /* Write the mask bits and read them back to determine which
+ * can be used. */
+ c->watch_reg_count = 1;
+ c->watch_reg_use_cnt = 1;
+ t = read_c0_watchhi0();
+ write_c0_watchhi0(t | 0xff8);
+ t = read_c0_watchhi0();
+ c->watch_reg_masks[0] |= (t & 0xff8);
+ if ((t & 0x80000000) == 0)
+ return;
+
+ write_c0_watchlo1(7);
+ t = read_c0_watchlo1();
+ write_c0_watchlo1(0);
+ c->watch_reg_masks[1] = t & 7;
+
+ c->watch_reg_count = 2;
+ c->watch_reg_use_cnt = 2;
+ t = read_c0_watchhi1();
+ write_c0_watchhi1(t | 0xff8);
+ t = read_c0_watchhi1();
+ c->watch_reg_masks[1] |= (t & 0xff8);
+ if ((t & 0x80000000) == 0)
+ return;
+
+ write_c0_watchlo2(7);
+ t = read_c0_watchlo2();
+ write_c0_watchlo2(0);
+ c->watch_reg_masks[2] = t & 7;
+
+ c->watch_reg_count = 3;
+ c->watch_reg_use_cnt = 3;
+ t = read_c0_watchhi2();
+ write_c0_watchhi2(t | 0xff8);
+ t = read_c0_watchhi2();
+ c->watch_reg_masks[2] |= (t & 0xff8);
+ if ((t & 0x80000000) == 0)
+ return;
+
+ write_c0_watchlo3(7);
+ t = read_c0_watchlo3();
+ write_c0_watchlo3(0);
+ c->watch_reg_masks[3] = t & 7;
+
+ c->watch_reg_count = 4;
+ c->watch_reg_use_cnt = 4;
+ t = read_c0_watchhi3();
+ write_c0_watchhi3(t | 0xff8);
+ t = read_c0_watchhi3();
+ c->watch_reg_masks[3] |= (t & 0xff8);
+ if ((t & 0x80000000) == 0)
+ return;
+
+ /* We use at most 4, but probe and report up to 8. */
+ c->watch_reg_count = 5;
+ t = read_c0_watchhi4();
+ if ((t & 0x80000000) == 0)
+ return;
+
+ c->watch_reg_count = 6;
+ t = read_c0_watchhi5();
+ if ((t & 0x80000000) == 0)
+ return;
+
+ c->watch_reg_count = 7;
+ t = read_c0_watchhi6();
+ if ((t & 0x80000000) == 0)
+ return;
+
+ c->watch_reg_count = 8;
+}
diff --git a/include/asm-mips/cpu-info.h b/include/asm-mips/cpu-info.h
index 2de73db..744cd8f 100644
--- a/include/asm-mips/cpu-info.h
+++ b/include/asm-mips/cpu-info.h
@@ -12,6 +12,8 @@
#ifndef __ASM_CPU_INFO_H
#define __ASM_CPU_INFO_H
+#include <linux/types.h>
+
#include <asm/cache.h>
/*
@@ -69,6 +71,10 @@ struct cpuinfo_mips {
int tc_id; /* Thread Context number */
#endif
void *data; /* Additional data */
+ unsigned int watch_reg_count; /* Number that exist */
+ unsigned int watch_reg_use_cnt; /* Usable by ptrace */
+#define NUM_WATCH_REGS 4
+ u16 watch_reg_masks[NUM_WATCH_REGS];
} __attribute__((aligned(SMP_CACHE_BYTES)));
extern struct cpuinfo_mips cpu_data[];
diff --git a/include/asm-mips/processor.h b/include/asm-mips/processor.h
index a1e4453..18ee58e 100644
--- a/include/asm-mips/processor.h
+++ b/include/asm-mips/processor.h
@@ -105,6 +105,19 @@ struct mips_dsp_state {
{0,} \
}
+struct mips3264_watch_reg_state {
+ /* The width of watchlo is 32 in a 32 bit kernel and 64 in a
+ 64 bit kernel. We use unsigned long as it has the same
+ property. */
+ unsigned long watchlo[NUM_WATCH_REGS];
+ /* Only the mask and IRW bits from watchhi. */
+ u16 watchhi[NUM_WATCH_REGS];
+};
+
+union mips_watch_reg_state {
+ struct mips3264_watch_reg_state mips3264;
+};
+
typedef struct {
unsigned long seg;
} mm_segment_t;
@@ -137,6 +150,9 @@ struct thread_struct {
/* Saved state of the DSP ASE, if available. */
struct mips_dsp_state dsp;
+ /* Saved watch register state, if available. */
+ union mips_watch_reg_state watch;
+
/* Other stuff associated with the thread. */
unsigned long cp0_badvaddr; /* Last user fault */
unsigned long cp0_baduaddr; /* Last kernel fault accessing USEG */
@@ -193,6 +209,10 @@ struct thread_struct {
.dspcontrol = 0, \
}, \
/* \
+ * saved watch register stuff \
+ */ \
+ .watch = {{{0,},},}, \
+ /* \
* 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 bb30606..3f76de7 100644
--- a/include/asm-mips/thread_info.h
+++ b/include/asm-mips/thread_info.h
@@ -124,6 +124,7 @@ 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)
@@ -140,6 +141,7 @@ 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..20126ec
--- /dev/null
+++ b/include/asm-mips/watch.h
@@ -0,0 +1,32 @@
+/*
+ * 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 <linux/bitops.h>
+
+#include <asm/mipsregs.h>
+
+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);
+
+#ifdef CONFIG_HARDWARE_WATCHPOINTS
+#define __restore_watch() do { \
+ if (unlikely(test_bit(TIF_LOAD_WATCH, \
+ ¤t_thread_info()->flags))) { \
+ mips_install_watch_registers(); \
+ } \
+} while (0)
+
+#else
+#define __restore_watch() do {} while (0)
+#endif
+
+#endif /* _ASM_WATCH_H */
--
1.5.5.1
--
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