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/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _ASM_POWERPC_BOOK3S_32_KUP_H
#define _ASM_POWERPC_BOOK3S_32_KUP_H
#include <asm/bug.h>
#include <asm/book3s/32/mmu-hash.h>
#include <asm/mmu.h>
#include <asm/synch.h>
#ifndef __ASSEMBLY__
static __always_inline bool kuep_is_disabled(void)
{
return !IS_ENABLED(CONFIG_PPC_KUEP);
}
static inline void kuep_lock(void)
{
if (kuep_is_disabled())
return;
update_user_segments(mfsr(0) | SR_NX);
/*
* This isync() shouldn't be necessary as the kernel is not excepted to
* run any instruction in userspace soon after the update of segments,
* but hash based cores (at least G3) seem to exhibit a random
* behaviour when the 'isync' is not there. 603 cores don't have this
* behaviour so don't do the 'isync' as it saves several CPU cycles.
*/
if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
isync(); /* Context sync required after mtsr() */
}
static inline void kuep_unlock(void)
{
if (kuep_is_disabled())
return;
update_user_segments(mfsr(0) & ~SR_NX);
/*
* This isync() shouldn't be necessary as a 'rfi' will soon be executed
* to return to userspace, but hash based cores (at least G3) seem to
* exhibit a random behaviour when the 'isync' is not there. 603 cores
* don't have this behaviour so don't do the 'isync' as it saves several
* CPU cycles.
*/
if (mmu_has_feature(MMU_FTR_HPTE_TABLE))
isync(); /* Context sync required after mtsr() */
}
#ifdef CONFIG_PPC_KUAP
#include <linux/sched.h>
static inline void kuap_update_sr(u32 sr, u32 addr, u32 end)
{
addr &= 0xf0000000; /* align addr to start of segment */
barrier(); /* make sure thread.kuap is updated before playing with SRs */
while (addr < end) {
mtsr(sr, addr);
sr += 0x111; /* next VSID */
sr &= 0xf0ffffff; /* clear VSID overflow */
addr += 0x10000000; /* address of next segment */
}
isync(); /* Context sync required after mtsr() */
}
static inline void kuap_save_and_lock(struct pt_regs *regs)
{
unsigned long kuap = current->thread.kuap;
u32 addr = kuap & 0xf0000000;
u32 end = kuap << 28;
regs->kuap = kuap;
if (unlikely(!kuap))
return;
current->thread.kuap = 0;
kuap_update_sr(mfsr(addr) | SR_KS, addr, end); /* Set Ks */
}
static inline void kuap_user_restore(struct pt_regs *regs)
{
}
static inline void kuap_kernel_restore(struct pt_regs *regs, unsigned long kuap)
{
u32 addr = regs->kuap & 0xf0000000;
u32 end = regs->kuap << 28;
current->thread.kuap = regs->kuap;
if (unlikely(regs->kuap == kuap))
return;
kuap_update_sr(mfsr(addr) & ~SR_KS, addr, end); /* Clear Ks */
}
static inline unsigned long kuap_get_and_assert_locked(void)
{
unsigned long kuap = current->thread.kuap;
WARN_ON_ONCE(IS_ENABLED(CONFIG_PPC_KUAP_DEBUG) && kuap != 0);
return kuap;
}
static inline void kuap_assert_locked(void)
{
kuap_get_and_assert_locked();
}
static __always_inline void allow_user_access(void __user *to, const void __user *from,
u32 size, unsigned long dir)
{
u32 addr, end;
BUILD_BUG_ON(!__builtin_constant_p(dir));
BUILD_BUG_ON(dir & ~KUAP_READ_WRITE);
if (!(dir & KUAP_WRITE))
return;
addr = (__force u32)to;
if (unlikely(addr >= TASK_SIZE || !size))
return;
end = min(addr + size, TASK_SIZE);
current->thread.kuap = (addr & 0xf0000000) | ((((end - 1) >> 28) + 1) & 0xf);
kuap_update_sr(mfsr(addr) & ~SR_KS, addr, end); /* Clear Ks */
}
static __always_inline void prevent_user_access(void __user *to, const void __user *from,
u32 size, unsigned long dir)
{
u32 addr, end;
BUILD_BUG_ON(!__builtin_constant_p(dir));
if (dir & KUAP_CURRENT_WRITE) {
u32 kuap = current->thread.kuap;
if (unlikely(!kuap))
return;
addr = kuap & 0xf0000000;
end = kuap << 28;
} else if (dir & KUAP_WRITE) {
addr = (__force u32)to;
end = min(addr + size, TASK_SIZE);
if (unlikely(addr >= TASK_SIZE || !size))
return;
} else {
return;
}
current->thread.kuap = 0;
kuap_update_sr(mfsr(addr) | SR_KS, addr, end); /* set Ks */
}
static inline unsigned long prevent_user_access_return(void)
{
unsigned long flags = current->thread.kuap;
unsigned long addr = flags & 0xf0000000;
unsigned long end = flags << 28;
void __user *to = (__force void __user *)addr;
if (flags)
prevent_user_access(to, to, end - addr, KUAP_READ_WRITE);
return flags;
}
static inline void restore_user_access(unsigned long flags)
{
unsigned long addr = flags & 0xf0000000;
unsigned long end = flags << 28;
void __user *to = (__force void __user *)addr;
if (flags)
allow_user_access(to, to, end - addr, KUAP_READ_WRITE);
}
static inline bool
bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write)
{
unsigned long begin = regs->kuap & 0xf0000000;
unsigned long end = regs->kuap << 28;
return is_write && (address < begin || address >= end);
}
#endif /* CONFIG_PPC_KUAP */
#endif /* __ASSEMBLY__ */
#endif /* _ASM_POWERPC_BOOK3S_32_KUP_H */
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