From 8bdc052eccdc7893d075d3f1f7103594a458c8c4 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Wed, 8 Nov 2006 17:44:49 -0800 Subject: [PATCH] [PATCH] kretprobe: fix kretprobe-booster to save regs and set status There are two bugs in the kretprobe-booster. 1) It doesn't make room for gs registers. 2) It doesn't change status of the current kprobe. This status will effect the fault handling. This patch fixes these bugs and, additionally, saves skipped registers for compatibility with the original kretprobe. Signed-off-by: Masami Hiramatsu Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/i386/kernel/kprobes.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) diff --git a/arch/i386/kernel/kprobes.c b/arch/i386/kernel/kprobes.c index d98e44b16f..fc79e1e859 100644 --- a/arch/i386/kernel/kprobes.c +++ b/arch/i386/kernel/kprobes.c @@ -361,8 +361,11 @@ no_kprobe: asm volatile ( ".global kretprobe_trampoline\n" "kretprobe_trampoline: \n" " pushf\n" - /* skip cs, eip, orig_eax, es, ds */ - " subl $20, %esp\n" + /* skip cs, eip, orig_eax */ + " subl $12, %esp\n" + " pushl %gs\n" + " pushl %ds\n" + " pushl %es\n" " pushl %eax\n" " pushl %ebp\n" " pushl %edi\n" @@ -373,10 +376,10 @@ no_kprobe: " movl %esp, %eax\n" " call trampoline_handler\n" /* move eflags to cs */ - " movl 48(%esp), %edx\n" - " movl %edx, 44(%esp)\n" + " movl 52(%esp), %edx\n" + " movl %edx, 48(%esp)\n" /* save true return address on eflags */ - " movl %eax, 48(%esp)\n" + " movl %eax, 52(%esp)\n" " popl %ebx\n" " popl %ecx\n" " popl %edx\n" @@ -384,8 +387,8 @@ no_kprobe: " popl %edi\n" " popl %ebp\n" " popl %eax\n" - /* skip eip, orig_eax, es, ds */ - " addl $16, %esp\n" + /* skip eip, orig_eax, es, ds, gs */ + " addl $20, %esp\n" " popf\n" " ret\n"); } @@ -404,6 +407,10 @@ fastcall void *__kprobes trampoline_handler(struct pt_regs *regs) INIT_HLIST_HEAD(&empty_rp); spin_lock_irqsave(&kretprobe_lock, flags); head = kretprobe_inst_table_head(current); + /* fixup registers */ + regs->xcs = __KERNEL_CS; + regs->eip = trampoline_address; + regs->orig_eax = 0xffffffff; /* * It is possible to have multiple instances associated with a given @@ -425,6 +432,7 @@ fastcall void *__kprobes trampoline_handler(struct pt_regs *regs) if (ri->rp && ri->rp->handler){ __get_cpu_var(current_kprobe) = &ri->rp->kp; + get_kprobe_ctlblk()->kprobe_status = KPROBE_HIT_ACTIVE; ri->rp->handler(ri, regs); __get_cpu_var(current_kprobe) = NULL; } -- 2.39.5