From eb232b1624462752dc916d9015b31ecdac0a01f1 Mon Sep 17 00:00:00 2001 From: "Aneesh Kumar K.V" Date: Fri, 27 Nov 2020 10:14:18 +0530 Subject: [PATCH] powerpc/book3s64/kuap: Improve error reporting with KUAP With hash translation use DSISR_KEYFAULT to identify a wrong access. With Radix we look at the AMR value and type of fault. Signed-off-by: Aneesh Kumar K.V Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20201127044424.40686-17-aneesh.kumar@linux.ibm.com --- arch/powerpc/include/asm/book3s/32/kup.h | 4 +-- arch/powerpc/include/asm/book3s/64/kup.h | 27 ++++++++++++++++---- arch/powerpc/include/asm/kup.h | 4 +-- arch/powerpc/include/asm/nohash/32/kup-8xx.h | 4 +-- arch/powerpc/mm/fault.c | 2 +- 5 files changed, 29 insertions(+), 12 deletions(-) diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h index 32fd4452e960..b18cd931e325 100644 --- a/arch/powerpc/include/asm/book3s/32/kup.h +++ b/arch/powerpc/include/asm/book3s/32/kup.h @@ -177,8 +177,8 @@ static inline void restore_user_access(unsigned long 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) +static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address, + bool is_write, unsigned long error_code) { unsigned long begin = regs->kuap & 0xf0000000; unsigned long end = regs->kuap << 28; diff --git a/arch/powerpc/include/asm/book3s/64/kup.h b/arch/powerpc/include/asm/book3s/64/kup.h index 4fa0760a47a4..f8f87b5c0e67 100644 --- a/arch/powerpc/include/asm/book3s/64/kup.h +++ b/arch/powerpc/include/asm/book3s/64/kup.h @@ -303,12 +303,29 @@ static inline void set_kuap(unsigned long value) isync(); } -static inline bool -bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) +#define RADIX_KUAP_BLOCK_READ UL(0x4000000000000000) +#define RADIX_KUAP_BLOCK_WRITE UL(0x8000000000000000) + +static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address, + bool is_write, unsigned long error_code) { - return WARN(mmu_has_feature(MMU_FTR_BOOK3S_KUAP) && - (regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE : AMR_KUAP_BLOCK_READ)), - "Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read"); + if (!mmu_has_feature(MMU_FTR_BOOK3S_KUAP)) + return false; + + if (radix_enabled()) { + /* + * Will be a storage protection fault. + * Only check the details of AMR[0] + */ + return WARN((regs->kuap & (is_write ? RADIX_KUAP_BLOCK_WRITE : RADIX_KUAP_BLOCK_READ)), + "Bug: %s fault blocked by AMR!", is_write ? "Write" : "Read"); + } + /* + * We don't want to WARN here because userspace can setup + * keys such that a kernel access to user address can cause + * fault + */ + return !!(error_code & DSISR_KEYFAULT); } static __always_inline void allow_user_access(void __user *to, const void __user *from, diff --git a/arch/powerpc/include/asm/kup.h b/arch/powerpc/include/asm/kup.h index a06e50b68d40..952be0414f43 100644 --- a/arch/powerpc/include/asm/kup.h +++ b/arch/powerpc/include/asm/kup.h @@ -59,8 +59,8 @@ void setup_kuap(bool disabled); #else static inline void setup_kuap(bool disabled) { } -static inline bool -bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) +static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address, + bool is_write, unsigned long error_code) { return false; } diff --git a/arch/powerpc/include/asm/nohash/32/kup-8xx.h b/arch/powerpc/include/asm/nohash/32/kup-8xx.h index 567cdc557402..7bdd9e5b63ed 100644 --- a/arch/powerpc/include/asm/nohash/32/kup-8xx.h +++ b/arch/powerpc/include/asm/nohash/32/kup-8xx.h @@ -60,8 +60,8 @@ static inline void restore_user_access(unsigned long flags) mtspr(SPRN_MD_AP, flags); } -static inline bool -bad_kuap_fault(struct pt_regs *regs, unsigned long address, bool is_write) +static inline bool bad_kuap_fault(struct pt_regs *regs, unsigned long address, + bool is_write, unsigned long error_code) { return WARN(!((regs->kuap ^ MD_APG_KUAP) & 0xff000000), "Bug: fault blocked by AP register !"); diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 0add963a849b..c91621df0c61 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -227,7 +227,7 @@ static bool bad_kernel_fault(struct pt_regs *regs, unsigned long error_code, // Read/write fault in a valid region (the exception table search passed // above), but blocked by KUAP is bad, it can never succeed. - if (bad_kuap_fault(regs, address, is_write)) + if (bad_kuap_fault(regs, address, is_write, error_code)) return true; // What's left? Kernel fault on user in well defined regions (extable -- 2.39.5