ARM: 6357/1: hw-breakpoint: add new ptrace requests for hw-breakpoint interaction

For debuggers to take advantage of the hw-breakpoint framework in the kernel,
it is necessary to expose the API calls via a ptrace interface.

This patch exposes the hardware breakpoints framework as a collection of
virtual registers, accesible using PTRACE_SETHBPREGS and PTRACE_GETHBPREGS
requests. The breakpoints are stored in the debug_info struct of the running
thread.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: S. Karthikeyan <informkarthik@gmail.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
index 401e38be1f78..974af1c3eb1d 100644
--- a/arch/arm/kernel/process.c
+++ b/arch/arm/kernel/process.c
@@ -29,6 +29,7 @@
 #include <linux/utsname.h>
 #include <linux/uaccess.h>
 #include <linux/random.h>
+#include <linux/hw_breakpoint.h>
 
 #include <asm/cacheflush.h>
 #include <asm/leds.h>
@@ -317,6 +318,8 @@ void flush_thread(void)
         struct thread_info *thread = current_thread_info();
         struct task_struct *tsk = current;
 
+        flush_ptrace_hw_breakpoint(tsk);
+
         memset(thread->used_cp, 0, sizeof(thread->used_cp));
         memset(&tsk->thread.debug, 0, sizeof(struct debug_info));
         memset(&thread->fpstate, 0, sizeof(union fp_state));
@@ -345,6 +348,8 @@ copy_thread(unsigned long clone_flags, unsigned long stack_start,
         thread->cpu_context.sp = (unsigned long)childregs;
         thread->cpu_context.pc = (unsigned long)ret_from_fork;
 
+        clear_ptrace_hw_breakpoint(p);
+
         if (clone_flags & CLONE_SETTLS)
                 thread->tp_value = regs->ARM_r3;