From 09a6adf53d42ca3088fa3fb41f40b768efc711ed Mon Sep 17 00:00:00 2001 From: Victor Kamensky Date: Mon, 3 Apr 2017 22:51:01 -0700 Subject: [PATCH] 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 4bf899f..1b35b8bd 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)) -- 2.7.4