Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753107AbdF0KPM (ORCPT ); Tue, 27 Jun 2017 06:15:12 -0400 Received: from mail-qt0-f196.google.com ([209.85.216.196]:36250 "EHLO mail-qt0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752335AbdF0KMm (ORCPT ); Tue, 27 Jun 2017 06:12:42 -0400 From: Ram Pai To: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org Cc: benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, khandual@linux.vnet.ibm.com, aneesh.kumar@linux.vnet.ibm.com, bsingharora@gmail.com, dave.hansen@intel.com, hbabu@us.ibm.com, linuxram@us.ibm.com, arnd@arndb.de, akpm@linux-foundation.org, corbet@lwn.net, mingo@redhat.com Subject: [RFC v4 12/17] powerpc: Deliver SEGV signal on pkey violation Date: Tue, 27 Jun 2017 03:11:54 -0700 Message-Id: <1498558319-32466-13-git-send-email-linuxram@us.ibm.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1498558319-32466-1-git-send-email-linuxram@us.ibm.com> References: <1498558319-32466-1-git-send-email-linuxram@us.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7342 Lines: 219 The value of the AMR register at the time of exception is made available in gp_regs[PT_AMR] of the siginfo. The value of the pkey, whose protection got violated, is made available in si_pkey field of the siginfo structure. Signed-off-by: Ram Pai --- arch/powerpc/include/asm/paca.h | 1 + arch/powerpc/include/uapi/asm/ptrace.h | 3 ++- arch/powerpc/kernel/asm-offsets.c | 5 ++++ arch/powerpc/kernel/exceptions-64s.S | 16 +++++++++-- arch/powerpc/kernel/signal_32.c | 5 ++++ arch/powerpc/kernel/signal_64.c | 4 +++ arch/powerpc/kernel/traps.c | 49 ++++++++++++++++++++++++++++++++++ arch/powerpc/mm/fault.c | 2 ++ 8 files changed, 82 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/include/asm/paca.h b/arch/powerpc/include/asm/paca.h index 1c09f8f..a41afd3 100644 --- a/arch/powerpc/include/asm/paca.h +++ b/arch/powerpc/include/asm/paca.h @@ -92,6 +92,7 @@ struct paca_struct { struct dtl_entry *dispatch_log_end; #endif /* CONFIG_PPC_STD_MMU_64 */ u64 dscr_default; /* per-CPU default DSCR */ + u64 paca_amr; /* value of amr at exception */ #ifdef CONFIG_PPC_STD_MMU_64 /* diff --git a/arch/powerpc/include/uapi/asm/ptrace.h b/arch/powerpc/include/uapi/asm/ptrace.h index 8036b38..7ec2428 100644 --- a/arch/powerpc/include/uapi/asm/ptrace.h +++ b/arch/powerpc/include/uapi/asm/ptrace.h @@ -108,8 +108,9 @@ struct pt_regs { #define PT_DAR 41 #define PT_DSISR 42 #define PT_RESULT 43 -#define PT_DSCR 44 #define PT_REGS_COUNT 44 +#define PT_DSCR 44 +#define PT_AMR 45 #define PT_FPR0 48 /* each FP reg occupies 2 slots in this space */ diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c index 709e234..17f5d8a 100644 --- a/arch/powerpc/kernel/asm-offsets.c +++ b/arch/powerpc/kernel/asm-offsets.c @@ -241,6 +241,11 @@ int main(void) OFFSET(PACAHWCPUID, paca_struct, hw_cpu_id); OFFSET(PACAKEXECSTATE, paca_struct, kexec_state); OFFSET(PACA_DSCR_DEFAULT, paca_struct, dscr_default); + +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS + OFFSET(PACA_AMR, paca_struct, paca_amr); +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ + OFFSET(ACCOUNT_STARTTIME, paca_struct, accounting.starttime); OFFSET(ACCOUNT_STARTTIME_USER, paca_struct, accounting.starttime_user); OFFSET(ACCOUNT_USER_TIME, paca_struct, accounting.utime); diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S index 3fd0528..a4de1b4 100644 --- a/arch/powerpc/kernel/exceptions-64s.S +++ b/arch/powerpc/kernel/exceptions-64s.S @@ -493,9 +493,15 @@ EXC_COMMON_BEGIN(data_access_common) ld r12,_MSR(r1) ld r3,PACA_EXGEN+EX_DAR(r13) lwz r4,PACA_EXGEN+EX_DSISR(r13) - li r5,0x300 std r3,_DAR(r1) std r4,_DSISR(r1) +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS + andis. r0,r4,DSISR_KEYFAULT@h /* save AMR only if its a key fault */ + beq+ 1f + mfspr r5,SPRN_AMR + std r5,PACA_AMR(r13) +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ +1: li r5,0x300 BEGIN_MMU_FTR_SECTION b do_hash_page /* Try to handle as hpte fault */ MMU_FTR_SECTION_ELSE @@ -561,9 +567,15 @@ EXC_COMMON_BEGIN(instruction_access_common) ld r12,_MSR(r1) ld r3,_NIP(r1) andis. r4,r12,0x5820 - li r5,0x400 std r3,_DAR(r1) std r4,_DSISR(r1) +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS + andis. r0,r4,DSISR_KEYFAULT@h /* save AMR only if its a key fault */ + beq+ 1f + mfspr r5,SPRN_AMR + std r5,PACA_AMR(r13) +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ +1: li r5,0x400 BEGIN_MMU_FTR_SECTION b do_hash_page /* Try to handle as hpte fault */ MMU_FTR_SECTION_ELSE diff --git a/arch/powerpc/kernel/signal_32.c b/arch/powerpc/kernel/signal_32.c index 97bb138..9c4a7f3 100644 --- a/arch/powerpc/kernel/signal_32.c +++ b/arch/powerpc/kernel/signal_32.c @@ -500,6 +500,11 @@ static int save_user_regs(struct pt_regs *regs, struct mcontext __user *frame, (unsigned long) &frame->tramp[2]); } +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS + if (__put_user(get_paca()->paca_amr, &frame->mc_gregs[PT_AMR])) + return 1; +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ + return 0; } diff --git a/arch/powerpc/kernel/signal_64.c b/arch/powerpc/kernel/signal_64.c index c83c115..86a4262 100644 --- a/arch/powerpc/kernel/signal_64.c +++ b/arch/powerpc/kernel/signal_64.c @@ -174,6 +174,10 @@ static long setup_sigcontext(struct sigcontext __user *sc, if (set != NULL) err |= __put_user(set->sig[0], &sc->oldmask); +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS + err |= __put_user(get_paca()->paca_amr, &sc->gp_regs[PT_AMR]); +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ + return err; } diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c index d4e545d..cc4bde8b 100644 --- a/arch/powerpc/kernel/traps.c +++ b/arch/powerpc/kernel/traps.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -247,6 +248,49 @@ void user_single_step_siginfo(struct task_struct *tsk, info->si_addr = (void __user *)regs->nip; } +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS +static void fill_sig_info_pkey(int si_code, siginfo_t *info, unsigned long addr) +{ + struct vm_area_struct *vma; + + /* Fault not from Protection Keys: nothing to do */ + if (si_code != SEGV_PKUERR) + return; + + down_read(¤t->mm->mmap_sem); + /* + * we could be racing with pkey_mprotect(). + * If pkey_mprotect() wins the key value could + * get modified...xxx + */ + vma = find_vma(current->mm, addr); + up_read(¤t->mm->mmap_sem); + + /* + * force_sig_info_fault() is called from a number of + * contexts, some of which have a VMA and some of which + * do not. The Pkey-fault handing happens after we have a + * valid VMA, so we should never reach this without a + * valid VMA. + */ + if (!vma) { + WARN_ONCE(1, "Pkey fault with no VMA passed in"); + info->si_pkey = 0; + return; + } + + /* + * We could report the incorrect key because of the reason + * explained above. + * + * si_pkey should be thought off as a strong hint, but not + * an absolutely guarantee because of the race explained + * above. + */ + info->si_pkey = vma_pkey(vma); +} +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ + void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr) { siginfo_t info; @@ -274,6 +318,11 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr) info.si_signo = signr; info.si_code = code; info.si_addr = (void __user *) addr; + +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS + fill_sig_info_pkey(code, &info, addr); +#endif /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ + force_sig_info(signr, &info, current); } diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c index 3d71984..0780a53 100644 --- a/arch/powerpc/mm/fault.c +++ b/arch/powerpc/mm/fault.c @@ -451,6 +451,8 @@ int do_page_fault(struct pt_regs *regs, unsigned long address, #ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE, is_exec, 0)) { + /* our caller may not have saved the amr. Lets save it */ + get_paca()->paca_amr = read_amr(); code = SEGV_PKUERR; goto bad_area; } -- 1.8.3.1