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// SPDX-License-Identifier: GPL-2.0
#include <linux/ptrace.h>
#include <asm/bugs.h>
#include <asm/traps.h>
static __ro_after_init bool ibt_fatal = true;
extern void ibt_selftest_ip(void); /* code label defined in asm below */
enum cp_error_code {
CP_EC = (1 << 15) - 1,
CP_RET = 1,
CP_IRET = 2,
CP_ENDBR = 3,
CP_RSTRORSSP = 4,
CP_SETSSBSY = 5,
CP_ENCL = 1 << 15,
};
DEFINE_IDTENTRY_ERRORCODE(exc_control_protection)
{
if (!cpu_feature_enabled(X86_FEATURE_IBT)) {
pr_err("Unexpected #CP\n");
BUG();
}
if (WARN_ON_ONCE(user_mode(regs) || (error_code & CP_EC) != CP_ENDBR))
return;
if (unlikely(regs->ip == (unsigned long)&ibt_selftest_ip)) {
regs->ax = 0;
return;
}
pr_err("Missing ENDBR: %pS\n", (void *)instruction_pointer(regs));
if (!ibt_fatal) {
printk(KERN_DEFAULT CUT_HERE);
__warn(__FILE__, __LINE__, (void *)regs->ip, TAINT_WARN, regs, NULL);
return;
}
BUG();
}
/* Must be noinline to ensure uniqueness of ibt_selftest_ip. */
noinline bool ibt_selftest(void)
{
unsigned long ret;
asm (" lea ibt_selftest_ip(%%rip), %%rax\n\t"
ANNOTATE_RETPOLINE_SAFE
" jmp *%%rax\n\t"
"ibt_selftest_ip:\n\t"
UNWIND_HINT_FUNC
ANNOTATE_NOENDBR
" nop\n\t"
: "=a" (ret) : : "memory");
return !ret;
}
static int __init ibt_setup(char *str)
{
if (!strcmp(str, "off"))
setup_clear_cpu_cap(X86_FEATURE_IBT);
if (!strcmp(str, "warn"))
ibt_fatal = false;
return 1;
}
__setup("ibt=", ibt_setup);
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