From 09a6adf53d42ca3088fa3fb41f40b768efc711ed Mon Sep 17 00:00:00 2001 From: Victor Kamensky Date: Mon, 3 Apr 2017 22:51:01 -0700 Subject: [PATCH 1/2] arm64: mm: unaligned access by user-land should be received as SIGBUS After 52d7523 (arm64: mm: allow the kernel to handle alignment faults on user accesses) commit user-land accesses that produce unaligned exceptions like in case of aarch32 ldm/stm/ldrd/strd instructions operating on unaligned memory received by user-land as SIGSEGV. It is wrong, it should be reported as SIGBUS as it was before 52d7523 commit. Changed do_bad_area function to take signal and code parameters out of esr value using fault_info table, so in case of do_alignment_fault fault user-land will receive SIGBUS. Wrapped access to fault_info table into esr_to_fault_info function. Cc: Fixes: 52d7523 (arm64: mm: allow the kernel to handle alignment faults on user accesses) Signed-off-by: Victor Kamensky Signed-off-by: Will Deacon --- arch/arm64/mm/fault.c | 42 ++++++++++++++++++++++++------------------ 1 file changed, 24 insertions(+), 18 deletions(-) diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 4bf899fb451b..1b35b8bddbfb 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -42,7 +42,20 @@ #include #include -static const char *fault_name(unsigned int esr); +struct fault_info { + int (*fn)(unsigned long addr, unsigned int esr, + struct pt_regs *regs); + int sig; + int code; + const char *name; +}; + +static const struct fault_info fault_info[]; + +static inline const struct fault_info *esr_to_fault_info(unsigned int esr) +{ + return fault_info + (esr & 63); +} #ifdef CONFIG_KPROBES static inline int notify_page_fault(struct pt_regs *regs, unsigned int esr) @@ -197,10 +210,12 @@ static void __do_user_fault(struct task_struct *tsk, unsigned long addr, struct pt_regs *regs) { struct siginfo si; + const struct fault_info *inf; if (unhandled_signal(tsk, sig) && show_unhandled_signals_ratelimited()) { + inf = esr_to_fault_info(esr); pr_info("%s[%d]: unhandled %s (%d) at 0x%08lx, esr 0x%03x\n", - tsk->comm, task_pid_nr(tsk), fault_name(esr), sig, + tsk->comm, task_pid_nr(tsk), inf->name, sig, addr, esr); show_pte(tsk->mm, addr); show_regs(regs); @@ -219,14 +234,16 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re { struct task_struct *tsk = current; struct mm_struct *mm = tsk->active_mm; + const struct fault_info *inf; /* * If we are in kernel mode at this point, we have no context to * handle this fault with. */ - if (user_mode(regs)) - __do_user_fault(tsk, addr, esr, SIGSEGV, SEGV_MAPERR, regs); - else + if (user_mode(regs)) { + inf = esr_to_fault_info(esr); + __do_user_fault(tsk, addr, esr, inf->sig, inf->code, regs); + } else __do_kernel_fault(mm, addr, esr, regs); } @@ -488,12 +505,7 @@ static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs) return 1; } -static const struct fault_info { - int (*fn)(unsigned long addr, unsigned int esr, struct pt_regs *regs); - int sig; - int code; - const char *name; -} fault_info[] = { +static const struct fault_info fault_info[] = { { do_bad, SIGBUS, 0, "ttbr address size fault" }, { do_bad, SIGBUS, 0, "level 1 address size fault" }, { do_bad, SIGBUS, 0, "level 2 address size fault" }, @@ -560,19 +572,13 @@ static const struct fault_info { { do_bad, SIGBUS, 0, "unknown 63" }, }; -static const char *fault_name(unsigned int esr) -{ - const struct fault_info *inf = fault_info + (esr & 63); - return inf->name; -} - /* * Dispatch a data abort to the relevant handler. */ asmlinkage void __exception do_mem_abort(unsigned long addr, unsigned int esr, struct pt_regs *regs) { - const struct fault_info *inf = fault_info + (esr & 63); + const struct fault_info *inf = esr_to_fault_info(esr); struct siginfo info; if (!inf->fn(addr, esr, regs)) From 6ae979ab39a368c18ceb0424bf824d172d6ab56f Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Fri, 31 Mar 2017 12:23:43 +0100 Subject: [PATCH 2/2] Revert "Revert "arm64: hugetlb: partial revert of 66b3923a1a0f"" The use of the contiguous bit by our hugetlb implementation violates the break-before-make requirements of the architecture and can lead to silent data corruption or TLB conflict aborts. Once again, disable these hugetlb sizes whilst it gets worked out. This reverts commit ab2e1b89230fa80328262c91d2d0a539a2790d6f. Conflicts: arch/arm64/mm/hugetlbpage.c Signed-off-by: Will Deacon --- arch/arm64/mm/hugetlbpage.c | 14 -------------- 1 file changed, 14 deletions(-) diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c index e25584d72396..7514a000e361 100644 --- a/arch/arm64/mm/hugetlbpage.c +++ b/arch/arm64/mm/hugetlbpage.c @@ -294,10 +294,6 @@ static __init int setup_hugepagesz(char *opt) hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT); } else if (ps == PUD_SIZE) { hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT); - } else if (ps == (PAGE_SIZE * CONT_PTES)) { - hugetlb_add_hstate(CONT_PTE_SHIFT); - } else if (ps == (PMD_SIZE * CONT_PMDS)) { - hugetlb_add_hstate((PMD_SHIFT + CONT_PMD_SHIFT) - PAGE_SHIFT); } else { hugetlb_bad_size(); pr_err("hugepagesz: Unsupported page size %lu K\n", ps >> 10); @@ -306,13 +302,3 @@ static __init int setup_hugepagesz(char *opt) return 1; } __setup("hugepagesz=", setup_hugepagesz); - -#ifdef CONFIG_ARM64_64K_PAGES -static __init int add_default_hugepagesz(void) -{ - if (size_to_hstate(CONT_PTES * PAGE_SIZE) == NULL) - hugetlb_add_hstate(CONT_PTE_SHIFT); - return 0; -} -arch_initcall(add_default_hugepagesz); -#endif