From eca23f3dbde340a85adbeb3ea4e81df5cbc10c0b Mon Sep 17 00:00:00 2001
From: srikar <srikar>
Date: Thu, 25 Oct 2007 13:54:41 +0000
Subject: [PATCH] uprobes ppc64 ssol changes

---
 runtime/uprobes/uprobes.c       |   4 ++
 runtime/uprobes/uprobes_ppc64.c | 111 ++++++++++++++++++++++++++++++++
 runtime/uprobes/uprobes_ppc64.h |  23 +++----
 3 files changed, 124 insertions(+), 14 deletions(-)

diff --git a/runtime/uprobes/uprobes.c b/runtime/uprobes/uprobes.c
index 9f5fddd08..509307095 100644
--- a/runtime/uprobes/uprobes.c
+++ b/runtime/uprobes/uprobes.c
@@ -40,6 +40,8 @@
 #define SET_ENGINE_FLAGS	1
 #define CLEAR_ENGINE_FLAGS	0
 
+#define MAX_SSOL_SLOTS		1024
+
 extern int access_process_vm(struct task_struct *tsk, unsigned long addr,
 	void *buf, int len, int write);
 static int utask_fake_quiesce(struct uprobe_task *utask);
@@ -1240,6 +1242,8 @@ static noinline void uprobe_init_ssol(struct uprobe_process *uproc)
 		return;
 
 	area->nfree = area->nslots = PAGE_SIZE / MAX_UINSN_BYTES;
+	if (area->nslots > MAX_SSOL_SLOTS)
+		area->nfree = area->nslots = MAX_SSOL_SLOTS;
 	area->slots = (struct uprobe_ssol_slot *)
 		kzalloc(sizeof(struct uprobe_ssol_slot) * area->nslots,
 								GFP_USER);
diff --git a/runtime/uprobes/uprobes_ppc64.c b/runtime/uprobes/uprobes_ppc64.c
index d80676e92..819ac73da 100644
--- a/runtime/uprobes/uprobes_ppc64.c
+++ b/runtime/uprobes/uprobes_ppc64.c
@@ -31,6 +31,117 @@ unsigned long arch_hijack_uret_addr(unsigned long trampoline_address,
 		struct pt_regs *regs, struct uprobe_task *utask)
 {
 	unsigned long orig_ret_addr = regs->link;
+
 	regs->link = trampoline_address;
 	return orig_ret_addr;
 }
+
+/*
+ * Get an instruction slot from the process's SSOL area, containing the
+ * instruction at ppt's probepoint.  Point the eip at that slot, in preparation
+ * for single-stepping out of line.
+ */
+static
+void uprobe_pre_ssout(struct uprobe_task *utask, struct uprobe_probept *ppt,
+		struct pt_regs *regs)
+{
+	struct uprobe_ssol_slot *slot;
+
+	slot = uprobe_get_insn_slot(ppt);
+	if (!slot) {
+		utask->doomed = 1;
+		return;
+	}
+	regs->nip = (long)slot->insn;
+}
+
+
+static inline void calc_offset(struct uprobe_probept *ppt,
+	       struct pt_regs *regs)
+{
+	int offset = 0;
+	unsigned int opcode = 0;
+	unsigned int insn = *ppt->insn;
+
+	opcode = insn >> 26;
+	switch (opcode) {
+	case 16:	/* bc */
+		if ((insn & 2) == 0) {
+			offset = (signed short)(insn & 0xfffc);
+			regs->nip = ppt->vaddr + offset;
+		}
+		if (insn & 1)
+			regs->link = ppt->vaddr + MAX_UINSN_BYTES;
+		break;
+	case 17:	/* sc */
+		/* Do we need to do anything */
+		break;
+	case 18:	/* b */
+		if ((insn & 2) == 0) {
+			offset = insn & 0x03fffffc;
+			if (offset & 0x02000000)
+				offset -= 0x04000000;
+			regs->nip = ppt->vaddr + offset;
+		}
+		if (insn & 1)
+			regs->link = ppt->vaddr + MAX_UINSN_BYTES;
+		break;
+	}
+#ifdef UPROBES_DEBUG
+	printk (KERN_ERR "ppt->vaddr=%p, regs->nip=%p, offset=%ld\n",
+			ppt->vaddr, regs->nip, offset);
+	if (insn & 1)
+		printk (KERN_ERR "regs->link=%p \n", regs->link);
+#endif
+	return;
+}
+
+/*
+ * Called after single-stepping.  ppt->vaddr is the address of the
+ * instruction which was replaced by a breakpoint instruction.  To avoid
+ * the SMP problems that can occur when we temporarily put back the
+ * original opcode to single-step, we single-stepped a copy of the
+ * instruction.
+ *
+ * This function prepares to return from the post-single-step
+ * interrupt.
+ *
+ * 1) Typically, the new nip is relative to the copied instruction.  We
+ * need to make it relative to the original instruction.  Exceptions are
+ * branch instructions.
+ *
+ * 2) For branch instructions, update the nip if the branch uses
+ * relative addressing.  Update the link instruction to the instruction
+ * following the original instruction address.
+ */
+
+static
+void uprobe_post_ssout(struct uprobe_task *utask, struct uprobe_probept *ppt,
+		struct pt_regs *regs)
+{
+	unsigned long copy_nip;
+
+	copy_nip = (unsigned long) ppt->slot->insn;
+	up_read(&ppt->slot->rwsem);
+
+	/*
+	 * If the single stepped instruction is non-branch instruction
+	 * then update the IP to be relative to probepoint.
+	 */
+	if (regs->nip == copy_nip + MAX_UINSN_BYTES)
+		regs->nip = ppt->vaddr + MAX_UINSN_BYTES;
+	else
+		calc_offset(ppt,regs);
+}
+
+static
+int arch_validate_probed_insn(struct uprobe_probept *ppt,
+		 struct task_struct *tsk)
+{
+	if ((unsigned long)ppt->vaddr & 0x03) {
+		printk(KERN_WARNING
+			"Attempt to register uprobe at an unaligned addr\n");
+		return -EINVAL;
+	}
+	return 0;
+}
diff --git a/runtime/uprobes/uprobes_ppc64.h b/runtime/uprobes/uprobes_ppc64.h
index 9f56119a4..1e274a945 100644
--- a/runtime/uprobes/uprobes_ppc64.h
+++ b/runtime/uprobes/uprobes_ppc64.h
@@ -27,7 +27,7 @@
 #define SSTEP_SIGNAL SIGTRAP
 
 /* Normally defined in Kconfig */
-#undef CONFIG_UPROBES_SSOL
+#define CONFIG_UPROBES_SSOL
 #define CONFIG_URETPROBES 1
 
 typedef unsigned int uprobe_opcode_t;
@@ -46,12 +46,6 @@ struct uprobe_probept;
 struct uprobe_task;
 struct task_struct;
 
-static inline int arch_validate_probed_insn(struct uprobe_probept *ppt,
-						struct task_struct *tsk)
-{
-	return 0;
-}
-
 /* On powerpc, nip points to the trap. */
 static inline unsigned long arch_get_probept(struct pt_regs *regs)
 {
@@ -62,14 +56,15 @@ static inline void arch_reset_ip_for_sstep(struct pt_regs *regs)
 {
 }
 
-#ifdef CONFIG_URETPROBES
-static inline void arch_restore_uret_addr(unsigned long ret_addr,
-		                struct pt_regs *regs)
-{
-	        regs->nip = ret_addr;
-}
-#endif /* CONFIG_URETPROBES */
+static inline int arch_validate_probed_insn(struct uprobe_probept *ppt,
+						struct task_struct *tsk);
 
 static unsigned long arch_hijack_uret_addr(unsigned long trampoline_addr,
 		struct pt_regs *regs, struct uprobe_task *utask);
+
+static inline void arch_restore_uret_addr(unsigned long ret_addr,
+		struct pt_regs *regs)
+{
+	regs->nip = ret_addr;
+}
 #endif				/* _ASM_UPROBES_H */
-- 
2.43.5