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hansendcKAGA-KOKO
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x86/pkeys: Add self-tests
This code should be a good demonstration of how to use the new system calls as well as how to use protection keys in general. This code shows how to: 1. Manipulate the Protection Keys Rights User (PKRU) register 2. Set a protection key on memory 3. Fetch and/or modify PKRU from the signal XSAVE state 4. Read the kernel-provided protection key in the siginfo 5. Set up an execute-only mapping There are currently 13 tests: test_read_of_write_disabled_region test_read_of_access_disabled_region test_write_of_write_disabled_region test_write_of_access_disabled_region test_kernel_write_of_access_disabled_region test_kernel_write_of_write_disabled_region test_kernel_gup_of_access_disabled_region test_kernel_gup_write_to_write_disabled_region test_executing_on_unreadable_memory test_ptrace_of_child test_pkey_syscalls_on_non_allocated_pkey test_pkey_syscalls_bad_args test_pkey_alloc_exhaust Each of the tests is run with plain memory (via mmap(MAP_ANON)), transparent huge pages, and hugetlb. Signed-off-by: Dave Hansen <[email protected]> Cc: [email protected] Cc: Dave Hansen <[email protected]> Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Cc: [email protected] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Thomas Gleixner <[email protected]>
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‎tools/testing/selftests/x86/Makefile

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@@ -5,7 +5,8 @@ include ../lib.mk
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.PHONY: all all_32 all_64 warn_32bit_failure clean
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TARGETS_C_BOTHBITS := single_step_syscall sysret_ss_attrs syscall_nt ptrace_syscall test_mremap_vdso \
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check_initial_reg_state sigreturn ldt_gdt iopl mpx-mini-test
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check_initial_reg_state sigreturn ldt_gdt iopl \
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protection_keys
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TARGETS_C_32BIT_ONLY := entry_from_vm86 syscall_arg_fault test_syscall_vdso unwind_vdso \
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test_FCMOV test_FCOMI test_FISTTP \
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vdso_restorer

‎tools/testing/selftests/x86/pkey-helpers.h

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

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