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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _PKEYS_HELPER_H
#define _PKEYS_HELPER_H
#define _GNU_SOURCE
#include <string.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdint.h>
#include <stdbool.h>
#include <signal.h>
#include <assert.h>
#include <stdlib.h>
#include <ucontext.h>
#include <sys/mman.h>
#define NR_PKEYS 16
#define PKRU_BITS_PER_PKEY 2
#ifndef DEBUG_LEVEL
#define DEBUG_LEVEL 0
#endif
#define DPRINT_IN_SIGNAL_BUF_SIZE 4096
extern int dprint_in_signal;
extern char dprint_in_signal_buffer[DPRINT_IN_SIGNAL_BUF_SIZE];
static inline void sigsafe_printf(const char *format, ...)
{
va_list ap;
if (!dprint_in_signal) {
va_start(ap, format);
vprintf(format, ap);
va_end(ap);
} else {
int ret;
/*
* No printf() functions are signal-safe.
* They deadlock easily. Write the format
* string to get some output, even if
* incomplete.
*/
ret = write(1, format, strlen(format));
if (ret < 0)
exit(1);
}
}
#define dprintf_level(level, args...) do { \
if (level <= DEBUG_LEVEL) \
sigsafe_printf(args); \
} while (0)
#define dprintf0(args...) dprintf_level(0, args)
#define dprintf1(args...) dprintf_level(1, args)
#define dprintf2(args...) dprintf_level(2, args)
#define dprintf3(args...) dprintf_level(3, args)
#define dprintf4(args...) dprintf_level(4, args)
extern unsigned int shadow_pkru;
static inline unsigned int __rdpkru(void)
{
unsigned int eax, edx;
unsigned int ecx = 0;
unsigned int pkru;
asm volatile(".byte 0x0f,0x01,0xee\n\t"
: "=a" (eax), "=d" (edx)
: "c" (ecx));
pkru = eax;
return pkru;
}
static inline unsigned int _rdpkru(int line)
{
unsigned int pkru = __rdpkru();
dprintf4("rdpkru(line=%d) pkru: %x shadow: %x\n",
line, pkru, shadow_pkru);
assert(pkru == shadow_pkru);
return pkru;
}
#define rdpkru() _rdpkru(__LINE__)
static inline void __wrpkru(unsigned int pkru)
{
unsigned int eax = pkru;
unsigned int ecx = 0;
unsigned int edx = 0;
dprintf4("%s() changing %08x to %08x\n", __func__, __rdpkru(), pkru);
asm volatile(".byte 0x0f,0x01,0xef\n\t"
: : "a" (eax), "c" (ecx), "d" (edx));
assert(pkru == __rdpkru());
}
static inline void wrpkru(unsigned int pkru)
{
dprintf4("%s() changing %08x to %08x\n", __func__, __rdpkru(), pkru);
/* will do the shadow check for us: */
rdpkru();
__wrpkru(pkru);
shadow_pkru = pkru;
dprintf4("%s(%08x) pkru: %08x\n", __func__, pkru, __rdpkru());
}
/*
* These are technically racy. since something could
* change PKRU between the read and the write.
*/
static inline void __pkey_access_allow(int pkey, int do_allow)
{
unsigned int pkru = rdpkru();
int bit = pkey * 2;
if (do_allow)
pkru &= (1<<bit);
else
pkru |= (1<<bit);
dprintf4("pkru now: %08x\n", rdpkru());
wrpkru(pkru);
}
static inline void __pkey_write_allow(int pkey, int do_allow_write)
{
long pkru = rdpkru();
int bit = pkey * 2 + 1;
if (do_allow_write)
pkru &= (1<<bit);
else
pkru |= (1<<bit);
wrpkru(pkru);
dprintf4("pkru now: %08x\n", rdpkru());
}
#define PROT_PKEY0 0x10 /* protection key value (bit 0) */
#define PROT_PKEY1 0x20 /* protection key value (bit 1) */
#define PROT_PKEY2 0x40 /* protection key value (bit 2) */
#define PROT_PKEY3 0x80 /* protection key value (bit 3) */
#define PAGE_SIZE 4096
#define MB (1<<20)
static inline void __cpuid(unsigned int *eax, unsigned int *ebx,
unsigned int *ecx, unsigned int *edx)
{
/* ecx is often an input as well as an output. */
asm volatile(
"cpuid;"
: "=a" (*eax),
"=b" (*ebx),
"=c" (*ecx),
"=d" (*edx)
: "0" (*eax), "2" (*ecx));
}
/* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx) */
#define X86_FEATURE_PKU (1<<3) /* Protection Keys for Userspace */
#define X86_FEATURE_OSPKE (1<<4) /* OS Protection Keys Enable */
static inline int cpu_has_pku(void)
{
unsigned int eax;
unsigned int ebx;
unsigned int ecx;
unsigned int edx;
eax = 0x7;
ecx = 0x0;
__cpuid(&eax, &ebx, &ecx, &edx);
if (!(ecx & X86_FEATURE_PKU)) {
dprintf2("cpu does not have PKU\n");
return 0;
}
if (!(ecx & X86_FEATURE_OSPKE)) {
dprintf2("cpu does not have OSPKE\n");
return 0;
}
return 1;
}
#define XSTATE_PKRU_BIT (9)
#define XSTATE_PKRU 0x200
int pkru_xstate_offset(void)
{
unsigned int eax;
unsigned int ebx;
unsigned int ecx;
unsigned int edx;
int xstate_offset;
int xstate_size;
unsigned long XSTATE_CPUID = 0xd;
int leaf;
/* assume that XSTATE_PKRU is set in XCR0 */
leaf = XSTATE_PKRU_BIT;
{
eax = XSTATE_CPUID;
ecx = leaf;
__cpuid(&eax, &ebx, &ecx, &edx);
if (leaf == XSTATE_PKRU_BIT) {
xstate_offset = ebx;
xstate_size = eax;
}
}
if (xstate_size == 0) {
printf("could not find size/offset of PKRU in xsave state\n");
return 0;
}
return xstate_offset;
}
#endif /* _PKEYS_HELPER_H */
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