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git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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3a24ea0df8
To avoid a useless nop on top of every uaccess enable/disable and make life easier for objtool, replace static branches by ASM feature fixups that will nop KUAP enabling instructions out in the unlikely case KUAP is disabled at boottime. Leave it as is on book3s/64 for now, it will be handled later when objtool is activated on PPC64. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://msgid.link/671948788024fd890ec4ed175bc332dab8664ea5.1689091022.git.christophe.leroy@csgroup.eu
175 lines
3.7 KiB
C
175 lines
3.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _ASM_POWERPC_BOOK3S_32_KUP_H
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#define _ASM_POWERPC_BOOK3S_32_KUP_H
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#include <asm/bug.h>
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#include <asm/book3s/32/mmu-hash.h>
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#include <asm/mmu.h>
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#include <asm/synch.h>
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#ifndef __ASSEMBLY__
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#ifdef CONFIG_PPC_KUAP
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#include <linux/sched.h>
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#define KUAP_NONE (~0UL)
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static __always_inline void kuap_lock_one(unsigned long addr)
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{
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mtsr(mfsr(addr) | SR_KS, addr);
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isync(); /* Context sync required after mtsr() */
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}
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static __always_inline void kuap_unlock_one(unsigned long addr)
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{
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mtsr(mfsr(addr) & ~SR_KS, addr);
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isync(); /* Context sync required after mtsr() */
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}
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static __always_inline void uaccess_begin_32s(unsigned long addr)
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{
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unsigned long tmp;
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asm volatile(ASM_MMU_FTR_IFSET(
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"mfsrin %0, %1;"
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"rlwinm %0, %0, 0, %2;"
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"mtsrin %0, %1;"
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"isync", "", %3)
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: "=&r"(tmp)
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: "r"(addr), "i"(~SR_KS), "i"(MMU_FTR_KUAP)
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: "memory");
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}
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static __always_inline void uaccess_end_32s(unsigned long addr)
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{
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unsigned long tmp;
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asm volatile(ASM_MMU_FTR_IFSET(
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"mfsrin %0, %1;"
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"oris %0, %0, %2;"
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"mtsrin %0, %1;"
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"isync", "", %3)
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: "=&r"(tmp)
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: "r"(addr), "i"(SR_KS >> 16), "i"(MMU_FTR_KUAP)
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: "memory");
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}
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static __always_inline void __kuap_save_and_lock(struct pt_regs *regs)
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{
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unsigned long kuap = current->thread.kuap;
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regs->kuap = kuap;
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if (unlikely(kuap == KUAP_NONE))
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return;
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current->thread.kuap = KUAP_NONE;
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kuap_lock_one(kuap);
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}
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#define __kuap_save_and_lock __kuap_save_and_lock
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static __always_inline void kuap_user_restore(struct pt_regs *regs)
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{
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}
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static __always_inline void __kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
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{
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if (unlikely(kuap != KUAP_NONE)) {
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current->thread.kuap = KUAP_NONE;
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kuap_lock_one(kuap);
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}
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if (likely(regs->kuap == KUAP_NONE))
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return;
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current->thread.kuap = regs->kuap;
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kuap_unlock_one(regs->kuap);
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}
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static __always_inline unsigned long __kuap_get_and_assert_locked(void)
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{
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unsigned long kuap = current->thread.kuap;
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WARN_ON_ONCE(IS_ENABLED(CONFIG_PPC_KUAP_DEBUG) && kuap != KUAP_NONE);
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return kuap;
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}
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#define __kuap_get_and_assert_locked __kuap_get_and_assert_locked
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static __always_inline void allow_user_access(void __user *to, const void __user *from,
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u32 size, unsigned long dir)
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{
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BUILD_BUG_ON(!__builtin_constant_p(dir));
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if (!(dir & KUAP_WRITE))
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return;
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current->thread.kuap = (__force u32)to;
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uaccess_begin_32s((__force u32)to);
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}
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static __always_inline void prevent_user_access(unsigned long dir)
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{
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u32 kuap = current->thread.kuap;
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BUILD_BUG_ON(!__builtin_constant_p(dir));
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if (!(dir & KUAP_WRITE))
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return;
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current->thread.kuap = KUAP_NONE;
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uaccess_end_32s(kuap);
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}
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static __always_inline unsigned long prevent_user_access_return(void)
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{
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unsigned long flags = current->thread.kuap;
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if (flags != KUAP_NONE) {
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current->thread.kuap = KUAP_NONE;
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uaccess_end_32s(flags);
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}
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return flags;
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}
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static __always_inline void restore_user_access(unsigned long flags)
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{
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if (flags != KUAP_NONE) {
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current->thread.kuap = flags;
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uaccess_begin_32s(flags);
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}
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}
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static __always_inline bool
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__bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
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{
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unsigned long kuap = regs->kuap;
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if (!is_write)
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return false;
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if (kuap == KUAP_NONE)
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return true;
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/*
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* If faulting address doesn't match unlocked segment, change segment.
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* In case of unaligned store crossing two segments, emulate store.
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*/
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if ((kuap ^ address) & 0xf0000000) {
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if (!(kuap & 0x0fffffff) && address > kuap - 4 && fix_alignment(regs)) {
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regs_add_return_ip(regs, 4);
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emulate_single_step(regs);
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} else {
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regs->kuap = address;
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}
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}
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return false;
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}
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#endif /* CONFIG_PPC_KUAP */
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#endif /* __ASSEMBLY__ */
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#endif /* _ASM_POWERPC_BOOK3S_32_KUP_H */
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