[POWERPC] Allow ptrace write to pt_regs trap and orig_r3

This patch allows a ptracer to write to the "trap" and "orig_r3" words
of the pt_regs.

This, along with a subsequent patch to the signal restart code, should
enable gdb to properly handle syscall restarting after executing a separate
function (at least when there's no restart block).

This patch also removes ptrace32.c code toying directly with the registers
and makes it use the ptrace_get/put_reg() accessors for everything so that
the logic for checking what is permitted is in only one place.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 14 insertions, 13 deletions

diff --git a/arch/powerpc/kernel/ptrace32.c b/arch/powerpc/kernel/ptrace32.c
index 4511b422992f..aae6a988e183 100644
--- a/arch/powerpc/kernel/ptrace32.c
+++ b/arch/powerpc/kernel/ptrace32.c
@@ -206,7 +206,9 @@ long compat_sys_ptrace(int request, int pid, unsigned long addr,
                 else
                         part = 0;  /* want the 1st half of the register (left-most). */
 
-                /* Validate the input - check to see if address is on the wrong boundary or beyond the end of the user area */
+                /* Validate the input - check to see if address is on the wrong boundary
+                 * or beyond the end of the user area
+                 */
                 if ((addr & 3) || numReg > PT_FPSCR)
                         break;
 
@@ -270,8 +272,6 @@ long compat_sys_ptrace(int request, int pid, unsigned long addr,
                 if ((addr & 3) || (index > PT_FPSCR32))
                         break;
 
-                if (index == PT_ORIG_R3)
-                        break;
                 if (index < PT_FPR0) {
                         ret = ptrace_put_reg(child, index, data);
                 } else {
@@ -302,24 +302,25 @@ long compat_sys_ptrace(int request, int pid, unsigned long addr,
                 /* Determine which register the user wants */
                 index = (u64)addr >> 2;
                 numReg = index / 2;
+
                 /*
                  * Validate the input - check to see if address is on the
                  * wrong boundary or beyond the end of the user area
                  */
                 if ((addr & 3) || (numReg > PT_FPSCR))
                         break;
-                /* Insure it is a register we let them change */
-                if ((numReg == PT_ORIG_R3)
-                                || ((numReg > PT_CCR) && (numReg < PT_FPR0)))
-                        break;
-                if (numReg >= PT_FPR0) {
+                if (numReg < PT_FPR0) {
+                        unsigned long freg = ptrace_get_reg(child, numReg);
+                        if (index % 2)
+                                freg = (freg & ~0xfffffffful) | (data & 0xfffffffful);
+                        else
+                                freg = (freg & 0xfffffffful) | (data << 32);
+                        ret = ptrace_put_reg(child, numReg, freg);
+                } else {
                         flush_fp_to_thread(child);
+                        ((unsigned int *)child->thread.regs)[index] = data;
+                        ret = 0;
                 }
-                if (numReg == PT_MSR)
-                        data = (data & MSR_DEBUGCHANGE)
-                                | (child->thread.regs->msr & ~MSR_DEBUGCHANGE);
-                ((u32*)child->thread.regs)[index] = data;
-                ret = 0;
                 break;
         }