[POWERPC] Add compat handler for PTRACE_GETSIGINFO

Current versions of gdb require a working implementation of
PTRACE_GETSIGINFO for proper watchpoint support.  Since struct siginfo
contains pointers it must be converted when passed to a 32-bit debugger.

Signed-off-by: Andreas Schwab <schwab@suse.de>
Signed-off-by: Paul Mackerras <paulus@samba.org>

2 files changed, 29 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/ppc32.h b/arch/powerpc/kernel/ppc32.h
index 90e562771791..fda05e2211d6 100644
--- a/arch/powerpc/kernel/ppc32.h
+++ b/arch/powerpc/kernel/ppc32.h
@@ -135,4 +135,6 @@ struct ucontext32 {
         struct mcontext32       uc_mcontext;
 };
 
+extern int copy_siginfo_to_user32(struct compat_siginfo __user *d, siginfo_t *s);
+
 #endif  /* _PPC64_PPC32_H */
diff --git a/arch/powerpc/kernel/ptrace32.c b/arch/powerpc/kernel/ptrace32.c
index 4c1de6af4c09..9d30e10970ac 100644
--- a/arch/powerpc/kernel/ptrace32.c
+++ b/arch/powerpc/kernel/ptrace32.c
@@ -29,12 +29,15 @@
 #include <linux/security.h>
 #include <linux/signal.h>
 #include <linux/compat.h>
+#include <linux/elf.h>
 
 #include <asm/uaccess.h>
 #include <asm/page.h>
 #include <asm/pgtable.h>
 #include <asm/system.h>
 
+#include "ppc32.h"
+
 /*
  * does not yet catch signals sent when the child dies.
  * in exit.c or in signal.c.
@@ -64,6 +67,27 @@ static long compat_ptrace_old(struct task_struct *child, long request,
         return -EPERM;
 }
 
+static int compat_ptrace_getsiginfo(struct task_struct *child, compat_siginfo_t __user *data)
+{
+        siginfo_t lastinfo;
+        int error = -ESRCH;
+
+        read_lock(&tasklist_lock);
+        if (likely(child->sighand != NULL)) {
+                error = -EINVAL;
+                spin_lock_irq(&child->sighand->siglock);
+                if (likely(child->last_siginfo != NULL)) {
+                        lastinfo = *child->last_siginfo;
+                        error = 0;
+                }
+                spin_unlock_irq(&child->sighand->siglock);
+        }
+        read_unlock(&tasklist_lock);
+        if (!error)
+                return copy_siginfo_to_user32(data, &lastinfo);
+        return error;
+}
+
 long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
                         compat_ulong_t caddr, compat_ulong_t cdata)
 {
@@ -282,6 +306,9 @@ long compat_arch_ptrace(struct task_struct *child, compat_long_t request,
                         0, PT_REGS_COUNT * sizeof(compat_long_t),
                         compat_ptr(data));
 
+        case PTRACE_GETSIGINFO:
+                return compat_ptrace_getsiginfo(child, compat_ptr(data));
+
         case PTRACE_GETFPREGS:
         case PTRACE_SETFPREGS:
         case PTRACE_GETVRREGS: