uprobes/x86: Gather "riprel" functions together

Cosmetic. Move pre_xol_rip_insn() and handle_riprel_post_xol() up to
the closely related handle_riprel_insn(). This way it is simpler to
read and understand this code, and this lessens the number of ifdef's.

While at it, update the comment in handle_riprel_post_xol() as Jim
suggested.

TODO: rename them somehow to make the naming consistent.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Reviewed-by: Jim Keniston <jkenisto@us.ibm.com>

1 files changed, 53 insertions, 65 deletions

diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 963c121c0307..c52c30fa7871 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -313,6 +313,48 @@ handle_riprel_insn(struct arch_uprobe *auprobe, struct insn *insn)
         }
 }
 
+/*
+ * If we're emulating a rip-relative instruction, save the contents
+ * of the scratch register and store the target address in that register.
+ */
+static void
+pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,
+                                struct arch_uprobe_task *autask)
+{
+        if (auprobe->fixups & UPROBE_FIX_RIP_AX) {
+                autask->saved_scratch_register = regs->ax;
+                regs->ax = current->utask->vaddr;
+                regs->ax += auprobe->rip_rela_target_address;
+        } else if (auprobe->fixups & UPROBE_FIX_RIP_CX) {
+                autask->saved_scratch_register = regs->cx;
+                regs->cx = current->utask->vaddr;
+                regs->cx += auprobe->rip_rela_target_address;
+        }
+}
+
+static void
+handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)
+{
+        if (auprobe->fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) {
+                struct arch_uprobe_task *autask;
+
+                autask = &current->utask->autask;
+                if (auprobe->fixups & UPROBE_FIX_RIP_AX)
+                        regs->ax = autask->saved_scratch_register;
+                else
+                        regs->cx = autask->saved_scratch_register;
+
+                /*
+                 * The original instruction includes a displacement, and so
+                 * is 4 bytes longer than what we've just single-stepped.
+                 * Caller may need to apply other fixups to handle stuff
+                 * like "jmpq *...(%rip)" and "callq *...(%rip)".
+                 */
+                if (correction)
+                        *correction += 4;
+        }
+}
+
 static int validate_insn_64bits(struct arch_uprobe *auprobe, struct insn *insn)
 {
         insn_init(insn, auprobe->insn, true);
@@ -339,9 +381,19 @@ static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm,
         return validate_insn_64bits(auprobe, insn);
 }
 #else /* 32-bit: */
+/*
+ * No RIP-relative addressing on 32-bit
+ */
 static void handle_riprel_insn(struct arch_uprobe *auprobe, struct insn *insn)
 {
-        /* No RIP-relative addressing on 32-bit */
+}
+static void pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,
+                                struct arch_uprobe_task *autask)
+{
+}
+static void handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs,
+                                        long *correction)
+{
 }
 
 static int validate_insn_bits(struct arch_uprobe *auprobe, struct mm_struct *mm,  struct insn *insn)
@@ -415,34 +467,6 @@ int arch_uprobe_analyze_insn(struct arch_uprobe *auprobe, struct mm_struct *mm,
         return 0;
 }
 
-#ifdef CONFIG_X86_64
-/*
- * If we're emulating a rip-relative instruction, save the contents
- * of the scratch register and store the target address in that register.
- */
-static void
-pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,
-                                struct arch_uprobe_task *autask)
-{
-        if (auprobe->fixups & UPROBE_FIX_RIP_AX) {
-                autask->saved_scratch_register = regs->ax;
-                regs->ax = current->utask->vaddr;
-                regs->ax += auprobe->rip_rela_target_address;
-        } else if (auprobe->fixups & UPROBE_FIX_RIP_CX) {
-                autask->saved_scratch_register = regs->cx;
-                regs->cx = current->utask->vaddr;
-                regs->cx += auprobe->rip_rela_target_address;
-        }
-}
-#else
-static void
-pre_xol_rip_insn(struct arch_uprobe *auprobe, struct pt_regs *regs,
-                                struct arch_uprobe_task *autask)
-{
-        /* No RIP-relative addressing on 32-bit */
-}
-#endif
-
 /*
  * arch_uprobe_pre_xol - prepare to execute out of line.
  * @auprobe: the probepoint information.
@@ -492,42 +516,6 @@ static int adjust_ret_addr(unsigned long sp, long correction)
         return 0;
 }
 
-#ifdef CONFIG_X86_64
-static bool is_riprel_insn(struct arch_uprobe *auprobe)
-{
-        return ((auprobe->fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) != 0);
-}
-
-static void
-handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)
-{
-        if (is_riprel_insn(auprobe)) {
-                struct arch_uprobe_task *autask;
-
-                autask = &current->utask->autask;
-                if (auprobe->fixups & UPROBE_FIX_RIP_AX)
-                        regs->ax = autask->saved_scratch_register;
-                else
-                        regs->cx = autask->saved_scratch_register;
-
-                /*
-                 * The original instruction includes a displacement, and so
-                 * is 4 bytes longer than what we've just single-stepped.
-                 * Fall through to handle stuff like "jmpq *...(%rip)" and
-                 * "callq *...(%rip)".
-                 */
-                if (correction)
-                        *correction += 4;
-        }
-}
-#else
-static void
-handle_riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs, long *correction)
-{
-        /* No RIP-relative addressing on 32-bit */
-}
-#endif
-
 /*
  * If xol insn itself traps and generates a signal(Say,
  * SIGILL/SIGSEGV/etc), then detect the case where a singlestepped