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authorRoland McGrath <roland@redhat.com>2009-05-28 21:26:38 +0000
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-06-09 13:29:25 +1000
commitec097c84dff17511f2693e6ef6c3064dfbf0a3af (patch)
tree3eac516a13730dcb371c094c0e8d35c9768c9c23 /arch/powerpc/kernel/traps.c
parentdac4ccfb64bcdd5b4c248ccc22903d67486573cd (diff)
powerpc: Add PTRACE_SINGLEBLOCK support
Reworked by: Benjamin Herrenschmidt <benh@kernel.crashing.org> This adds block-step support on powerpc, including a PTRACE_SINGLEBLOCK request for ptrace. The BookE implementation is tweaked to fire a single step after a block step in order to mimmic the server behaviour. Signed-off-by: Roland McGrath <roland@redhat.com> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/kernel/traps.c')
-rw-r--r--arch/powerpc/kernel/traps.c34
1 files changed, 30 insertions, 4 deletions
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 6a5b2b731f4..6f0ae1a9bfa 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1041,7 +1041,34 @@ void SoftwareEmulation(struct pt_regs *regs)
void __kprobes DebugException(struct pt_regs *regs, unsigned long debug_status)
{
- if (debug_status & DBSR_IC) { /* instruction completion */
+ /* Hack alert: On BookE, Branch Taken stops on the branch itself, while
+ * on server, it stops on the target of the branch. In order to simulate
+ * the server behaviour, we thus restart right away with a single step
+ * instead of stopping here when hitting a BT
+ */
+ if (debug_status & DBSR_BT) {
+ regs->msr &= ~MSR_DE;
+
+ /* Disable BT */
+ mtspr(SPRN_DBCR0, mfspr(SPRN_DBCR0) & ~DBCR0_BT);
+ /* Clear the BT event */
+ mtspr(SPRN_DBSR, DBSR_BT);
+
+ /* Do the single step trick only when coming from userspace */
+ if (user_mode(regs)) {
+ current->thread.dbcr0 &= ~DBCR0_BT;
+ current->thread.dbcr0 |= DBCR0_IDM | DBCR0_IC;
+ regs->msr |= MSR_DE;
+ return;
+ }
+
+ if (notify_die(DIE_SSTEP, "block_step", regs, 5,
+ 5, SIGTRAP) == NOTIFY_STOP) {
+ return;
+ }
+ if (debugger_sstep(regs))
+ return;
+ } else if (debug_status & DBSR_IC) { /* Instruction complete */
regs->msr &= ~MSR_DE;
/* Disable instruction completion */
@@ -1057,9 +1084,8 @@ void __kprobes DebugException(struct pt_regs *regs, unsigned long debug_status)
if (debugger_sstep(regs))
return;
- if (user_mode(regs)) {
- current->thread.dbcr0 &= ~DBCR0_IC;
- }
+ if (user_mode(regs))
+ current->thread.dbcr0 &= ~(DBCR0_IC);
_exception(SIGTRAP, regs, TRAP_TRACE, regs->nip);
} else if (debug_status & (DBSR_DAC1R | DBSR_DAC1W)) {