static int is_setting_trap_flag(struct task_struct *child, struct pt_regs *regs)
{
int i, copied;
unsigned char opcode[15];
unsigned long addr = convert_ip_to_linear(child, regs);
copied = access_process_vm(child, addr, opcode, sizeof(opcode), 0);
for (i = 0; i < copied; i++) {
switch (opcode[i]) {
/* popf and iret */
case 0x9d: case 0xcf:
return 1;
/* CHECKME: 64 65 */
/* opcode and address size prefixes */
case 0x66: case 0x67:
continue;
/* irrelevant prefixes (segment overrides and repeats) */
case 0x26: case 0x2e:
case 0x36: case 0x3e:
case 0x64: case 0x65:
case 0xf0: case 0xf2: case 0xf3:
continue;
#ifdef CONFIG_X86_64
case 0x40 ... 0x4f:
if (!user_64bit_mode(regs))
/* 32-bit mode: register increment */
return 0;
/* 64-bit mode: REX prefix */
continue;
#endif
/* CHECKME: f2, f3 */
/*
* pushf: NOTE! We should probably not let
* the user see the TF bit being set. But
* it's more pain than it's worth to avoid
* it, and a debugger could emulate this
* all in user space if it _really_ cares.
*/
case 0x9c:
default:
return 0;
}
}
return 0;
}
void sigaction_compat_abi(struct k_sigaction *act, struct k_sigaction *oact)
{
/* Don't leak in-kernel non-uapi flags to user-space */
if (oact)
oact->sa.sa_flags &= ~(SA_IA32_ABI | SA_X32_ABI);
if (!act)
return;
/* Don't let flags to be set from userspace */
act->sa.sa_flags &= ~(SA_IA32_ABI | SA_X32_ABI);
if (user_64bit_mode(current_pt_regs()))
return;
if (in_ia32_syscall())
act->sa.sa_flags |= SA_IA32_ABI;
if (in_x32_syscall())
act->sa.sa_flags |= SA_X32_ABI;
}
void perf_get_regs_user(struct perf_regs *regs_user,
struct pt_regs *regs,
struct pt_regs *regs_user_copy)
{
struct pt_regs *user_regs = task_pt_regs(current);
/*
* If we're in an NMI that interrupted task_pt_regs setup, then
* we can't sample user regs at all. This check isn't really
* sufficient, though, as we could be in an NMI inside an interrupt
* that happened during task_pt_regs setup.
*/
if (regs->sp > (unsigned long)&user_regs->r11 &&
regs->sp <= (unsigned long)(user_regs + 1)) {
regs_user->abi = PERF_SAMPLE_REGS_ABI_NONE;
regs_user->regs = NULL;
return;
}
/*
* RIP, flags, and the argument registers are usually saved.
* orig_ax is probably okay, too.
*/
regs_user_copy->ip = user_regs->ip;
regs_user_copy->cx = user_regs->cx;
regs_user_copy->dx = user_regs->dx;
regs_user_copy->si = user_regs->si;
regs_user_copy->di = user_regs->di;
regs_user_copy->r8 = user_regs->r8;
regs_user_copy->r9 = user_regs->r9;
regs_user_copy->r10 = user_regs->r10;
regs_user_copy->r11 = user_regs->r11;
regs_user_copy->orig_ax = user_regs->orig_ax;
regs_user_copy->flags = user_regs->flags;
/*
* Don't even try to report the "rest" regs.
*/
regs_user_copy->bx = -1;
regs_user_copy->bp = -1;
regs_user_copy->r12 = -1;
regs_user_copy->r13 = -1;
regs_user_copy->r14 = -1;
regs_user_copy->r15 = -1;
/*
* For this to be at all useful, we need a reasonable guess for
* sp and the ABI. Be careful: we're in NMI context, and we're
* considering current to be the current task, so we should
* be careful not to look at any other percpu variables that might
* change during context switches.
*/
if (IS_ENABLED(CONFIG_IA32_EMULATION) &&
task_thread_info(current)->status & TS_COMPAT) {
/* Easy case: we're in a compat syscall. */
regs_user->abi = PERF_SAMPLE_REGS_ABI_32;
regs_user_copy->sp = user_regs->sp;
regs_user_copy->cs = user_regs->cs;
regs_user_copy->ss = user_regs->ss;
} else if (user_regs->orig_ax != -1) {
/*
* We're probably in a 64-bit syscall.
* Warning: this code is severely racy. At least it's better
* than just blindly copying user_regs.
*/
regs_user->abi = PERF_SAMPLE_REGS_ABI_64;
regs_user_copy->sp = this_cpu_read(old_rsp);
regs_user_copy->cs = __USER_CS;
regs_user_copy->ss = __USER_DS;
regs_user_copy->cx = -1; /* usually contains garbage */
} else {
/* We're probably in an interrupt or exception. */
regs_user->abi = user_64bit_mode(user_regs) ?
PERF_SAMPLE_REGS_ABI_64 : PERF_SAMPLE_REGS_ABI_32;
regs_user_copy->sp = user_regs->sp;
regs_user_copy->cs = user_regs->cs;
regs_user_copy->ss = user_regs->ss;
}
regs_user->regs = regs_user_copy;
}
