[PATCH 1/6] uprobes/x86: Add struct uretprobe_syscall_args

[Peter Zijlstra]

Like uprobe_syscall_args; keep things consistent.

Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
---
 arch/x86/kernel/uprobes.c |   33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

--- a/arch/x86/kernel/uprobes.c
+++ b/arch/x86/kernel/uprobes.c
@@ -311,6 +311,12 @@ static int uprobe_init_insn(struct arch_
 
 #ifdef CONFIG_X86_64
 
+struct uretprobe_syscall_args {
+       unsigned long r11;
+       unsigned long cx;
+       unsigned long ax;
+};
+
 asm (
        ".pushsection .rodata\n"
        ".global uretprobe_trampoline_entry\n"
@@ -324,8 +330,8 @@ asm (
        "uretprobe_syscall_check:\n"
        "popq %r11\n"
        "popq %rcx\n"
-
-       /* The uretprobe syscall replaces stored %rax value with final
+       /*
+        * The uretprobe syscall replaces stored %rax value with final
         * return address, so we don't restore %rax in here and just
         * call ret.
         */
@@ -366,7 +372,8 @@ static unsigned long trampoline_check_ip
 SYSCALL_DEFINE0(uretprobe)
 {
        struct pt_regs *regs = task_pt_regs(current);
-       unsigned long err, ip, sp, r11_cx_ax[3], tramp;
+       struct uretprobe_syscall_args args;
+       unsigned long err, ip, sp, tramp;
 
        /* If there's no trampoline, we are called from wrong place. */
        tramp = uprobe_get_trampoline_vaddr();
@@ -377,15 +384,15 @@ SYSCALL_DEFINE0(uretprobe)
        if (unlikely(regs->ip != trampoline_check_ip(tramp)))
                goto sigill;
 
-       err = copy_from_user(r11_cx_ax, (void __user *)regs->sp, 
sizeof(r11_cx_ax));
+       err = copy_from_user(&args, (void __user *)regs->sp, sizeof(args));
        if (err)
                goto sigill;
 
        /* expose the "right" values of r11/cx/ax/sp to uprobe_consumer/s */
-       regs->r11 = r11_cx_ax[0];
-       regs->cx  = r11_cx_ax[1];
-       regs->ax  = r11_cx_ax[2];
-       regs->sp += sizeof(r11_cx_ax);
+       regs->r11 = args.r11;
+       regs->cx  = args.cx;
+       regs->ax  = args.ax;
+       regs->sp += sizeof(args);
        regs->orig_ax = -1;
 
        ip = regs->ip;
@@ -401,21 +408,21 @@ SYSCALL_DEFINE0(uretprobe)
         */
        if (regs->sp != sp || shstk_is_enabled())
                return regs->ax;
-       regs->sp -= sizeof(r11_cx_ax);
+       regs->sp -= sizeof(args);
 
        /* for the case uprobe_consumer has changed r11/cx */
-       r11_cx_ax[0] = regs->r11;
-       r11_cx_ax[1] = regs->cx;
+       args.r11 = regs->r11;
+       args.cx  = regs->cx;
 
        /*
         * ax register is passed through as return value, so we can use
         * its space on stack for ip value and jump to it through the
         * trampoline's ret instruction
         */
-       r11_cx_ax[2] = regs->ip;
+       args.ax  = regs->ip;
        regs->ip = ip;
 
-       err = copy_to_user((void __user *)regs->sp, r11_cx_ax, 
sizeof(r11_cx_ax));
+       err = copy_to_user((void __user *)regs->sp, &args, sizeof(args));
        if (err)
                goto sigill;