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Subject[PATCH 3/6] x86: Allow the user not to build hw_breakpoints
Date
So that hw_breakpoints and perf can be not built on
specific embedded systems.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/Kconfig | 3 +--
arch/x86/include/asm/debugreg.h | 33 +++++++++++++++++++++++++++++++--
arch/x86/kernel/Makefile | 3 ++-
arch/x86/kernel/process.c | 1 +
arch/x86/kernel/ptrace.c | 17 +++++++++++++++++
5 files changed, 52 insertions(+), 5 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 8b49bff..fb28dd9 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -41,7 +41,7 @@ config X86
select HAVE_FTRACE_NMI_ENTER if DYNAMIC_FTRACE
select HAVE_SYSCALL_TRACEPOINTS
select HAVE_KVM
- select HAVE_ARCH_KGDB
+ select HAVE_ARCH_KGDB if HW_BREAKPOINT
select HAVE_ARCH_TRACEHOOK
select HAVE_GENERIC_DMA_COHERENT if X86_32
select HAVE_EFFICIENT_UNALIGNED_ACCESS
@@ -54,7 +54,6 @@ config X86
select HAVE_KERNEL_XZ
select HAVE_KERNEL_LZO
select HAVE_HW_BREAKPOINT
- select HW_BREAKPOINT
select HAVE_MIXED_BREAKPOINTS_REGS
select PERF_EVENTS
select HAVE_PERF_EVENTS_NMI
diff --git a/arch/x86/include/asm/debugreg.h b/arch/x86/include/asm/debugreg.h
index 078ad0c..c40d6d4 100644
--- a/arch/x86/include/asm/debugreg.h
+++ b/arch/x86/include/asm/debugreg.h
@@ -78,8 +78,6 @@
*/
#ifdef __KERNEL__

-DECLARE_PER_CPU(unsigned long, cpu_dr7);
-
static inline void hw_breakpoint_disable(void)
{
/* Zero the control register for HW Breakpoint */
@@ -92,6 +90,10 @@ static inline void hw_breakpoint_disable(void)
set_debugreg(0UL, 3);
}

+#ifdef CONFIG_HW_BREAKPOINT
+
+DECLARE_PER_CPU(unsigned long, cpu_dr7);
+
static inline int hw_breakpoint_active(void)
{
return __this_cpu_read(cpu_dr7) & DR_GLOBAL_ENABLE_MASK;
@@ -100,6 +102,33 @@ static inline int hw_breakpoint_active(void)
extern void aout_dump_debugregs(struct user *dump);

extern void hw_breakpoint_restore(void);
+#else
+static inline int hw_breakpoint_active(void)
+{
+ return 0;
+}
+
+static inline void hw_breakpoint_restore(void)
+{
+ set_debugreg(0UL, 0);
+ set_debugreg(0UL, 1);
+ set_debugreg(0UL, 2);
+ set_debugreg(0UL, 3);
+ set_debugreg(current->thread.debugreg6, 6);
+ set_debugreg(0UL, 7);
+}
+
+static inline void aout_dump_debugregs(struct user *dump)
+{
+ int i;
+
+ for (i = 0; i < 6; i++)
+ dump->u_debugreg[i] = 0;
+
+ dump->u_debugreg[6] = current->thread.debugreg6;
+ dump->u_debugreg[7] = 0;
+}
+#endif /* CONFIG_HW_BREAKPOINT */

#endif /* __KERNEL__ */

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 7338ef2..270e439 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -42,7 +42,7 @@ obj-$(CONFIG_X86_64) += sys_x86_64.o x8664_ksyms_64.o
obj-$(CONFIG_X86_64) += syscall_64.o vsyscall_64.o
obj-y += bootflag.o e820.o
obj-y += pci-dma.o quirks.o topology.o kdebugfs.o
-obj-y += alternative.o i8253.o pci-nommu.o hw_breakpoint.o
+obj-y += alternative.o i8253.o pci-nommu.o
obj-y += tsc.o io_delay.o rtc.o
obj-y += pci-iommu_table.o
obj-y += resource.o
@@ -51,6 +51,7 @@ obj-y += trampoline.o trampoline_$(BITS).o
obj-y += process.o
obj-y += i387.o xsave.o
obj-y += ptrace.o
+obj-$(CONFIG_HW_BREAKPOINT) += hw_breakpoint.o
obj-$(CONFIG_X86_32) += tls.o
obj-$(CONFIG_IA32_EMULATION) += tls.o
obj-y += step.o
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index d46cbe4..d1adbd1 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -22,6 +22,7 @@
#include <asm/uaccess.h>
#include <asm/i387.h>
#include <asm/debugreg.h>
+#include <asm/kdebug.h>

struct kmem_cache *task_xstate_cachep;
EXPORT_SYMBOL_GPL(task_xstate_cachep);
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index f65e5b5..091f110c 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -528,6 +528,7 @@ static int genregs_set(struct task_struct *target,
return ret;
}

+#ifdef CONFIG_HW_BREAKPOINT
static void ptrace_triggered(struct perf_event *bp, int nmi,
struct perf_sample_data *data,
struct pt_regs *regs)
@@ -777,6 +778,22 @@ ret_path:
return rc;
}

+#else /* !CONFIG_HW_BREAKPOINT */
+
+static inline unsigned long
+ptrace_get_debugreg(struct task_struct *tsk, int n)
+{
+ return -ENOSYS;
+}
+
+static inline
+int ptrace_set_debugreg(struct task_struct *tsk, int n, unsigned long val)
+{
+ return -ENOSYS;
+}
+
+#endif /* CONFIG_HW_BREAKPOINT */
+
/*
* These access the current or another (stopped) task's io permission
* bitmap for debugging or core dump.
--
1.7.3.2


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