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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>
134 lines
3.3 KiB
C
134 lines
3.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _PKEYS_POWERPC_H
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#define _PKEYS_POWERPC_H
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#ifndef SYS_pkey_alloc
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# define SYS_pkey_alloc 384
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# define SYS_pkey_free 385
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#endif
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#define REG_IP_IDX PT_NIP
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#define MCONTEXT_IP(mc) mc.gp_regs[REG_IP_IDX]
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#define MCONTEXT_TRAPNO(mc) mc.gp_regs[REG_TRAPNO]
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#define REG_TRAPNO PT_TRAP
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#define MCONTEXT_FPREGS
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#define gregs gp_regs
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#define fpregs fp_regs
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#define si_pkey_offset 0x20
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#undef PKEY_DISABLE_ACCESS
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#define PKEY_DISABLE_ACCESS 0x3 /* disable read and write */
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#undef PKEY_DISABLE_WRITE
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#define PKEY_DISABLE_WRITE 0x2
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#define NR_PKEYS 32
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#define NR_RESERVED_PKEYS_4K 27 /* pkey-0, pkey-1, exec-only-pkey
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and 24 other keys that cannot be
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represented in the PTE */
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#define NR_RESERVED_PKEYS_64K_3KEYS 3 /* PowerNV and KVM: pkey-0,
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pkey-1 and exec-only key */
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#define NR_RESERVED_PKEYS_64K_4KEYS 4 /* PowerVM: pkey-0, pkey-1,
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pkey-31 and exec-only key */
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#define PKEY_BITS_PER_PKEY 2
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#define HPAGE_SIZE (1UL << 24)
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#define PAGE_SIZE sysconf(_SC_PAGESIZE)
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static inline u32 pkey_bit_position(int pkey)
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{
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return (NR_PKEYS - pkey - 1) * PKEY_BITS_PER_PKEY;
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}
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static inline u64 __read_pkey_reg(void)
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{
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u64 pkey_reg;
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asm volatile("mfspr %0, 0xd" : "=r" (pkey_reg));
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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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u64 amr = pkey_reg;
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dprintf4("%s() changing %016llx to %016llx\n",
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__func__, __read_pkey_reg(), pkey_reg);
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asm volatile("isync; mtspr 0xd, %0; isync"
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: : "r" ((unsigned long)(amr)) : "memory");
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dprintf4("%s() pkey register after changing %016llx to %016llx\n",
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__func__, __read_pkey_reg(), pkey_reg);
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}
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static inline int cpu_has_pkeys(void)
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{
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/* No simple way to determine this */
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return 1;
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}
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static inline bool arch_is_powervm()
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{
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struct stat buf;
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if ((stat("/sys/firmware/devicetree/base/ibm,partition-name", &buf) == 0) &&
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(stat("/sys/firmware/devicetree/base/hmc-managed?", &buf) == 0) &&
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(stat("/sys/firmware/devicetree/base/chosen/qemu,graphic-width", &buf) == -1) )
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return true;
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return false;
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}
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static inline int get_arch_reserved_keys(void)
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{
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if (sysconf(_SC_PAGESIZE) == 4096)
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return NR_RESERVED_PKEYS_4K;
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else
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if (arch_is_powervm())
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return NR_RESERVED_PKEYS_64K_4KEYS;
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else
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return NR_RESERVED_PKEYS_64K_3KEYS;
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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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/*
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* powerpc does not allow userspace to change permissions of exec-only
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* keys since those keys are not allocated by userspace. The signal
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* handler wont be able to reset the permissions, which means the code
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* will infinitely continue to segfault here.
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*/
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return;
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}
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/* 4-byte instructions * 16384 = 64K page */
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#define __page_o_noops() asm(".rept 16384 ; nop; .endr")
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void *malloc_pkey_with_mprotect_subpage(long size, int prot, u16 pkey)
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{
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void *ptr;
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int ret;
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dprintf1("doing %s(size=%ld, prot=0x%x, pkey=%d)\n", __func__,
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size, prot, pkey);
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pkey_assert(pkey < NR_PKEYS);
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ptr = mmap(NULL, size, prot, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
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pkey_assert(ptr != (void *)-1);
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ret = syscall(__NR_subpage_prot, ptr, size, NULL);
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if (ret) {
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perror("subpage_perm");
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return PTR_ERR_ENOTSUP;
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}
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ret = mprotect_pkey((void *)ptr, PAGE_SIZE, prot, pkey);
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pkey_assert(!ret);
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record_pkey_malloc(ptr, size, prot);
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dprintf1("%s() for pkey %d @ %p\n", __func__, pkey, ptr);
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return ptr;
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}
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#endif /* _PKEYS_POWERPC_H */
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