diff options
Diffstat (limited to 'arch/powerpc/include/asm/book3s/32/kup.h')
| -rw-r--r-- | arch/powerpc/include/asm/book3s/32/kup.h | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h new file mode 100644 index 000000000..32fd4452e --- /dev/null +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -0,0 +1,197 @@ +/* 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> + +#ifdef __ASSEMBLY__ + +.macro kuep_update_sr gpr1, gpr2 /* NEVER use r0 as gpr2 due to addis */ +101: mtsrin \gpr1, \gpr2 + addi \gpr1, \gpr1, 0x111 /* next VSID */ + rlwinm \gpr1, \gpr1, 0, 0xf0ffffff /* clear VSID overflow */ + addis \gpr2, \gpr2, 0x1000 /* address of next segment */ + bdnz 101b + isync +.endm + +.macro kuep_lock gpr1, gpr2 +#ifdef CONFIG_PPC_KUEP + li \gpr1, NUM_USER_SEGMENTS + li \gpr2, 0 + mtctr \gpr1 + mfsrin \gpr1, \gpr2 + oris \gpr1, \gpr1, SR_NX@h /* set Nx */ + kuep_update_sr \gpr1, \gpr2 +#endif +.endm + +.macro kuep_unlock gpr1, gpr2 +#ifdef CONFIG_PPC_KUEP + li \gpr1, NUM_USER_SEGMENTS + li \gpr2, 0 + mtctr \gpr1 + mfsrin \gpr1, \gpr2 + rlwinm \gpr1, \gpr1, 0, ~SR_NX /* Clear Nx */ + kuep_update_sr \gpr1, \gpr2 +#endif +.endm + +#ifdef CONFIG_PPC_KUAP + +.macro kuap_update_sr gpr1, gpr2, gpr3 /* NEVER use r0 as gpr2 due to addis */ +101: mtsrin \gpr1, \gpr2 + addi \gpr1, \gpr1, 0x111 /* next VSID */ + rlwinm \gpr1, \gpr1, 0, 0xf0ffffff /* clear VSID overflow */ + addis \gpr2, \gpr2, 0x1000 /* address of next segment */ + cmplw \gpr2, \gpr3 + blt- 101b + isync +.endm + +.macro kuap_save_and_lock sp, thread, gpr1, gpr2, gpr3 + lwz \gpr2, KUAP(\thread) + rlwinm. \gpr3, \gpr2, 28, 0xf0000000 + stw \gpr2, STACK_REGS_KUAP(\sp) + beq+ 102f + li \gpr1, 0 + stw \gpr1, KUAP(\thread) + mfsrin \gpr1, \gpr2 + oris \gpr1, \gpr1, SR_KS@h /* set Ks */ + kuap_update_sr \gpr1, \gpr2, \gpr3 +102: +.endm + +.macro kuap_restore sp, current, gpr1, gpr2, gpr3 + lwz \gpr2, STACK_REGS_KUAP(\sp) + rlwinm. \gpr3, \gpr2, 28, 0xf0000000 + stw \gpr2, THREAD + KUAP(\current) + beq+ 102f + mfsrin \gpr1, \gpr2 + rlwinm \gpr1, \gpr1, 0, ~SR_KS /* Clear Ks */ + kuap_update_sr \gpr1, \gpr2, \gpr3 +102: +.endm + +.macro kuap_check current, gpr +#ifdef CONFIG_PPC_KUAP_DEBUG + lwz \gpr, THREAD + KUAP(\current) +999: twnei \gpr, 0 + EMIT_BUG_ENTRY 999b, __FILE__, __LINE__, (BUGFLAG_WARNING | BUGFLAG_ONCE) +#endif +.endm + +#endif /* CONFIG_PPC_KUAP */ + +#else /* !__ASSEMBLY__ */ + +#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) { + mtsrin(sr, addr); + sr += 0x111; /* next VSID */ + sr &= 0xf0ffffff; /* clear VSID overflow */ + addr += 0x10000000; /* address of next segment */ + } + isync(); /* Context sync required after mtsrin() */ +} + +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(mfsrin(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(mfsrin(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; + + if (!is_write) + return false; + + return WARN(address < begin || address >= end, + "Bug: write fault blocked by segment registers !"); +} + +#endif /* CONFIG_PPC_KUAP */ + +#endif /* __ASSEMBLY__ */ + +#endif /* _ASM_POWERPC_BOOK3S_32_KUP_H */ |