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The encoding of the pkey register differs on arm64, than on x86/ppc. On those platforms, a bit in the register is used to disable permissions, for arm64, a bit enabled in the register indicates that the permission is allowed. This drops two asserts of the form: assert(read_pkey_reg() <= orig_pkey_reg); Because on arm64 this doesn't hold, due to the encoding. The pkey must be reset to both access allow and write allow in the signal handler. pkey_access_allow() works currently for PowerPC as the PKEY_DISABLE_ACCESS and PKEY_DISABLE_WRITE have overlapping bits set. Access to the uc_mcontext is abstracted, as arm64 has a different structure. Signed-off-by: Joey Gouly <joey.gouly@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Acked-by: Dave Hansen <dave.hansen@linux.intel.com> Link: https://lore.kernel.org/r/20240822151113.1479789-27-joey.gouly@arm.com Signed-off-by: Will Deacon <will@kernel.org>
164 lines
3.3 KiB
C
164 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _PKEYS_X86_H
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#define _PKEYS_X86_H
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#ifdef __i386__
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#define REG_IP_IDX REG_EIP
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#define si_pkey_offset 0x14
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#else
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#define REG_IP_IDX REG_RIP
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#define si_pkey_offset 0x20
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#endif
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#define MCONTEXT_IP(mc) mc.gregs[REG_IP_IDX]
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#define MCONTEXT_TRAPNO(mc) mc.gregs[REG_TRAPNO]
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#define MCONTEXT_FPREGS
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#ifndef PKEY_DISABLE_ACCESS
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# define PKEY_DISABLE_ACCESS 0x1
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#endif
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#ifndef PKEY_DISABLE_WRITE
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# define PKEY_DISABLE_WRITE 0x2
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#endif
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#define NR_PKEYS 16
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#define NR_RESERVED_PKEYS 2 /* pkey-0 and exec-only-pkey */
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#define PKEY_BITS_PER_PKEY 2
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#define HPAGE_SIZE (1UL<<21)
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#define PAGE_SIZE 4096
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#define MB (1<<20)
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static inline void __page_o_noops(void)
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{
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/* 8-bytes of instruction * 512 bytes = 1 page */
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asm(".rept 512 ; nopl 0x7eeeeeee(%eax) ; .endr");
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}
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static inline u64 __read_pkey_reg(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 pkey_reg;
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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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pkey_reg = eax;
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return pkey_reg;
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}
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static inline void __write_pkey_reg(u64 pkey_reg)
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{
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unsigned int eax = pkey_reg;
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unsigned int ecx = 0;
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unsigned int edx = 0;
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dprintf4("%s() changing %016llx to %016llx\n", __func__,
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__read_pkey_reg(), pkey_reg);
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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(pkey_reg == __read_pkey_reg());
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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_pkeys(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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__cpuid_count(0x7, 0x0, 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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static inline int cpu_max_xsave_size(void)
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{
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unsigned long XSTATE_CPUID = 0xd;
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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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__cpuid_count(XSTATE_CPUID, 0, eax, ebx, ecx, edx);
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return ecx;
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}
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static inline u32 pkey_bit_position(int pkey)
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{
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return pkey * PKEY_BITS_PER_PKEY;
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}
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#define XSTATE_PKEY_BIT (9)
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#define XSTATE_PKEY 0x200
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#define XSTATE_BV_OFFSET 512
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int pkey_reg_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 = 0;
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unsigned long XSTATE_CPUID = 0xd;
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int leaf;
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/* assume that XSTATE_PKEY is set in XCR0 */
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leaf = XSTATE_PKEY_BIT;
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{
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__cpuid_count(XSTATE_CPUID, leaf, eax, ebx, ecx, edx);
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if (leaf == XSTATE_PKEY_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 PKEY 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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static inline int get_arch_reserved_keys(void)
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{
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return NR_RESERVED_PKEYS;
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}
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void expect_fault_on_read_execonly_key(void *p1, int pkey)
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{
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int ptr_contents;
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ptr_contents = read_ptr(p1);
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dprintf2("ptr (%p) contents@%d: %x\n", p1, __LINE__, ptr_contents);
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expected_pkey_fault(pkey);
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}
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void *malloc_pkey_with_mprotect_subpage(long size, int prot, u16 pkey)
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{
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return PTR_ERR_ENOTSUP;
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}
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#endif /* _PKEYS_X86_H */
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