From 2e7f844220b9419b2f05234b07c56bcdedf7afb2 Mon Sep 17 00:00:00 2001 From: Tim Moore Date: Wed, 16 Dec 2009 18:00:34 +0100 Subject: [PATCH] function to translate from the uretprobe trampoline back to the original return address * runtime/uprobes2/uprobes.c (uprobe_get_pc): new function --- runtime/uprobes2/uprobes.c | 38 ++++++++++++++++++++++++++++++++++++++ runtime/uprobes2/uprobes.h | 8 ++++++++ 2 files changed, 46 insertions(+), 0 deletions(-) diff --git a/runtime/uprobes2/uprobes.c b/runtime/uprobes2/uprobes.c index bf45475..4c3a9c9 100644 --- a/runtime/uprobes2/uprobes.c +++ b/runtime/uprobes2/uprobes.c @@ -2810,6 +2810,44 @@ static void uretprobe_set_trampoline(struct uprobe_process *uproc, } } +unsigned long uprobe_get_pc(struct uretprobe_instance *ri, unsigned long pc, + unsigned long sp) +{ + struct uretprobe *rp; + struct uprobe_kimg *uk; + struct uprobe_process *uproc; + unsigned long trampoline_addr; + struct hlist_node *r; + struct uretprobe_instance *ret_inst; + + if (!ri) + return 0; + rp = ri->rp; + uk = (struct uprobe_kimg *)rp->u.kdata; + if (!uk) + return 0; + uproc = uk->ppt->uproc; + if (IS_ERR(uproc->uretprobe_trampoline_addr)) + return pc; + trampoline_addr = (unsigned long)uproc->uretprobe_trampoline_addr; + if (pc != trampoline_addr) + return pc; + r = &ri->hlist; + hlist_for_each_entry_from(ret_inst, r, hlist) { + if (ret_inst->ret_addr == trampoline_addr) + continue; + /* First handler with a stack pointer lower than the + address (or equal) must be the one. */ + if (ret_inst->sp == sp || compare_stack_ptrs(ret_inst->sp, sp)) + return ret_inst->ret_addr; + } + printk(KERN_ERR "Original return address for trampoline not found at " + "0x%lx pid/tgid=%d/%d\n", sp, current->pid, current->tgid); + return 0; +} + +EXPORT_SYMBOL_GPL(uprobe_get_pc); + #else /* ! CONFIG_URETPROBES */ static void uretprobe_handle_entry(struct uprobe *u, struct pt_regs *regs, diff --git a/runtime/uprobes2/uprobes.h b/runtime/uprobes2/uprobes.h index ae0692f..5d2a826 100644 --- a/runtime/uprobes2/uprobes.h +++ b/runtime/uprobes2/uprobes.h @@ -88,6 +88,14 @@ extern void unregister_uretprobe(struct uretprobe *rp); /* For PRs 9940, 6852... */ extern void unmap_uprobe(struct uprobe *u); extern void unmap_uretprobe(struct uretprobe *rp); +/* + * Given a program counter, translate it back to the original address + * if it is the address of the trampoline. sp is the stack pointer for + * the frame that corresponds to the address. + */ +extern unsigned long uprobe_get_pc(struct uretprobe_instance *ri, + unsigned long pc, + unsigned long sp); #ifdef UPROBES_IMPLEMENTATION -- 1.6.2.5