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authorOleg Nesterov <oleg@redhat.com>2014-04-27 20:13:31 +0400
committerOleg Nesterov <oleg@redhat.com>2014-04-30 21:10:41 +0400
commitc90a6950120a7e45f31a22653fe6543507ae64d0 (patch)
tree1a842e0e6929ad050ddc696bc44c7c5c39af13dd /arch/x86/kernel/uprobes.c
parent7f55e82bacaaa2c41b8e14d6bc78129b096b67b8 (diff)
downloadlinux-c90a6950120a7e45f31a22653fe6543507ae64d0.tar.xz
uprobes/x86: Simplify riprel_{pre,post}_xol() and make them similar
Ignoring the "correction" logic riprel_pre_xol() and riprel_post_xol() are very similar but look quite differently. 1. Add the "UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX" check at the start of riprel_pre_xol(), like the same check in riprel_post_xol(). 2. Add the trivial scratch_reg() helper which returns the address of scratch register pre_xol/post_xol need to change. 3. Change these functions to use the new helper and avoid copy-and-paste under if/else branches. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Diffstat (limited to 'arch/x86/kernel/uprobes.c')
-rw-r--r--arch/x86/kernel/uprobes.c30
1 files changed, 14 insertions, 16 deletions
diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
index 5df1bca7c2bc..2ebadb252093 100644
--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -326,22 +326,24 @@ static void riprel_analyze(struct arch_uprobe *auprobe, struct insn *insn)
}
}
+static inline unsigned long *
+scratch_reg(struct arch_uprobe *auprobe, struct pt_regs *regs)
+{
+ return (auprobe->def.fixups & UPROBE_FIX_RIP_AX) ? &regs->ax : &regs->cx;
+}
+
/*
* 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 riprel_pre_xol(struct arch_uprobe *auprobe, struct pt_regs *regs)
{
- struct uprobe_task *utask = current->utask;
+ if (auprobe->def.fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) {
+ struct uprobe_task *utask = current->utask;
+ unsigned long *sr = scratch_reg(auprobe, regs);
- if (auprobe->def.fixups & UPROBE_FIX_RIP_AX) {
- utask->autask.saved_scratch_register = regs->ax;
- regs->ax = utask->vaddr;
- regs->ax += auprobe->def.riprel_target;
- } else if (auprobe->def.fixups & UPROBE_FIX_RIP_CX) {
- utask->autask.saved_scratch_register = regs->cx;
- regs->cx = utask->vaddr;
- regs->cx += auprobe->def.riprel_target;
+ utask->autask.saved_scratch_register = *sr;
+ *sr = utask->vaddr + auprobe->def.riprel_target;
}
}
@@ -349,14 +351,10 @@ static void riprel_post_xol(struct arch_uprobe *auprobe, struct pt_regs *regs,
long *correction)
{
if (auprobe->def.fixups & (UPROBE_FIX_RIP_AX | UPROBE_FIX_RIP_CX)) {
- struct arch_uprobe_task *autask;
-
- autask = &current->utask->autask;
- if (auprobe->def.fixups & UPROBE_FIX_RIP_AX)
- regs->ax = autask->saved_scratch_register;
- else
- regs->cx = autask->saved_scratch_register;
+ struct uprobe_task *utask = current->utask;
+ unsigned long *sr = scratch_reg(auprobe, regs);
+ *sr = utask->autask.saved_scratch_register;
/*
* The original instruction includes a displacement, and so
* is 4 bytes longer than what we've just single-stepped.