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uprobes/x86: Add struct uretprobe_syscall_args

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Like uprobe_syscall_args; keep things consistent.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250821123656.705837806@infradead.org
This commit is contained in:
Peter Zijlstra 2025-08-20 12:28:36 +02:00
parent ba2bfc97b4
commit 985e820b72
1 changed files with 20 additions and 13 deletions
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33
arch/x86/kernel/uprobes.c
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@ -311,6 +311,12 @@ static int uprobe_init_insn(struct arch_uprobe *auprobe, struct insn *insn, bool
#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(unsigned long tramp)
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;