On Wed, Aug 19, 2020 at 8:56 AM Dave Martin <Dave.Martin@xxxxxxx> wrote: > > On Mon, Aug 17, 2020 at 08:33:51PM -0700, Peter Collingbourne wrote: > > The kernel currently clears the tag bits (i.e. bits 56-63) in the fault > > address exposed via siginfo.si_addr and sigcontext.fault_address. However, > > the tag bits may be needed by tools in order to accurately diagnose > > memory errors, such as HWASan [1] or future tools based on the Memory > > Tagging Extension (MTE). > > > > We should not stop clearing these bits in the existing fault address > > fields, because there may be existing userspace applications that are > > expecting the tag bits to be cleared. Instead, create a new pair of > > union fields in siginfo._sigfault, and store the tag bits of FAR_EL1 > > there, together with a mask specifying which bits are valid. > > > > A flag is added to si_xflags to allow userspace to determine whether > > the values in the fields are valid. > > > > [1] http://clang.llvm.org/docs/HardwareAssistedAddressSanitizerDesign.html > > > > Signed-off-by: Peter Collingbourne <pcc@xxxxxxxxxx> > > --- > > View this change in Gerrit: https://linux-review.googlesource.com/q/Ia8876bad8c798e0a32df7c2ce1256c4771c81446 > > > > v9: > > - make the ignored bits fields generic > > - add some new dependent patches that prepare us to store the > > field in such a way that userspace can detect their presence > > > > v8: > > - rebase onto 5.8rc2 > > > > v7: > > - switch to a new siginfo field instead of using sigcontext > > - merge the patch back into one since the other patches are now > > unnecessary > > > > v6: > > - move fault address and fault code into the kernel_siginfo data structure > > - split the patch in three since it was getting large and now has > > generic and arch-specific parts > > > > v5: > > - add padding to fault_addr_top_byte_context in order to ensure the correct > > size and preserve sp alignment > > > > v4: > > - expose only the tag bits in the context instead of the entire FAR_EL1 > > - remove mention of the new context from the sigcontext.__reserved[] note > > > > v3: > > - add documentation to tagged-pointers.rst > > - update comments in sigcontext.h > > > > v2: > > - revert changes to hw_breakpoint.c > > - rename set_thread_esr to set_thread_far_esr > > > > Documentation/arm64/tagged-pointers.rst | 21 +++++++--- > > arch/arm64/include/asm/exception.h | 2 +- > > arch/arm64/include/asm/traps.h | 7 +++- > > arch/arm64/kernel/debug-monitors.c | 4 +- > > arch/arm64/kernel/entry-common.c | 2 - > > arch/arm64/kernel/ptrace.c | 2 +- > > arch/arm64/kernel/traps.c | 15 ++++--- > > arch/arm64/mm/fault.c | 54 ++++++++++++++----------- > > arch/mips/kernel/traps.c | 2 +- > > arch/parisc/kernel/ptrace.c | 2 +- > > arch/parisc/mm/fault.c | 2 +- > > arch/powerpc/mm/fault.c | 2 +- > > arch/x86/mm/fault.c | 3 +- > > include/linux/compat.h | 2 + > > include/linux/sched/signal.h | 12 +++++- > > include/uapi/asm-generic/siginfo.h | 10 +++++ > > kernel/signal.c | 50 +++++++++++++++++++---- > > mm/memory-failure.c | 2 +- > > 18 files changed, 136 insertions(+), 58 deletions(-) > > > > diff --git a/Documentation/arm64/tagged-pointers.rst b/Documentation/arm64/tagged-pointers.rst > > index eab4323609b9..bd23039841a5 100644 > > --- a/Documentation/arm64/tagged-pointers.rst > > +++ b/Documentation/arm64/tagged-pointers.rst > > @@ -53,12 +53,21 @@ visibility. > > Preserving tags > > --------------- > > > > -Non-zero tags are not preserved when delivering signals. This means that > > -signal handlers in applications making use of tags cannot rely on the > > -tag information for user virtual addresses being maintained for fields > > -inside siginfo_t. One exception to this rule is for signals raised in > > -response to watchpoint debug exceptions, where the tag information will > > -be preserved. > > +Non-zero tags are not preserved in the fault address fields > > +siginfo.si_addr or sigcontext.fault_address when delivering > > +signals. This means that signal handlers in applications making use > > +of tags cannot rely on the tag information for user virtual addresses > > +being maintained in these fields. One exception to this rule is for > > +signals raised in response to watchpoint debug exceptions, where the > > +tag information will be preserved. > > + > > +The fault address tag is preserved in the si_addr_ignored_bits field > > +of siginfo, which is set for signals raised in response to data aborts > > +and instruction aborts. The si_addr_ignored_bits_mask field indicates > > +which bits of the field are valid. The validity of these fields is > > +indicated by the SI_XFLAG_IGNORED_BITS flag in siginfo.si_xflags, > > +and the validity of si_xflags in turn is indicated by the kernel > > +indicating support for the sigaction.sa_flags flag SA_XFLAGS. > > > > The architecture prevents the use of a tagged PC, so the upper byte will > > be set to a sign-extension of bit 55 on exception return. > > diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h > > index 7577a754d443..950d55dae948 100644 > > --- a/arch/arm64/include/asm/exception.h > > +++ b/arch/arm64/include/asm/exception.h > > @@ -32,7 +32,7 @@ static inline u32 disr_to_esr(u64 disr) > > } > > > > asmlinkage void enter_from_user_mode(void); > > -void do_mem_abort(unsigned long addr, unsigned int esr, struct pt_regs *regs); > > +void do_mem_abort(unsigned long far, unsigned int esr, struct pt_regs *regs); > > void do_undefinstr(struct pt_regs *regs); > > void do_bti(struct pt_regs *regs); > > asmlinkage void bad_mode(struct pt_regs *regs, int reason, unsigned int esr); > > diff --git a/arch/arm64/include/asm/traps.h b/arch/arm64/include/asm/traps.h > > index cee5928e1b7d..8e4f6c5b97af 100644 > > --- a/arch/arm64/include/asm/traps.h > > +++ b/arch/arm64/include/asm/traps.h > > @@ -26,8 +26,11 @@ void register_undef_hook(struct undef_hook *hook); > > void unregister_undef_hook(struct undef_hook *hook); > > void force_signal_inject(int signal, int code, unsigned long address); > > void arm64_notify_segfault(unsigned long addr); > > -void arm64_force_sig_fault(int signo, int code, void __user *addr, const char *str); > > -void arm64_force_sig_mceerr(int code, void __user *addr, short lsb, const char *str); > > +void arm64_force_sig_fault(int signo, int code, void __user *addr, > > + unsigned long far, unsigned char far_tb_mask, > > + const char *str); > > +void arm64_force_sig_mceerr(int code, void __user *addr, short lsb, > > + unsigned long far, const char *str); > > void arm64_force_sig_ptrace_errno_trap(int errno, void __user *addr, const char *str); > > > > /* > > diff --git a/arch/arm64/kernel/debug-monitors.c b/arch/arm64/kernel/debug-monitors.c > > index 7310a4f7f993..bc9e02fbb710 100644 > > --- a/arch/arm64/kernel/debug-monitors.c > > +++ b/arch/arm64/kernel/debug-monitors.c > > @@ -235,8 +235,8 @@ static void send_user_sigtrap(int si_code) > > local_irq_enable(); > > > > arm64_force_sig_fault(SIGTRAP, si_code, > > - (void __user *)instruction_pointer(regs), > > - "User debug trap"); > > + (void __user *)instruction_pointer(regs), 0, 0, > > + "User debug trap"); > > } > > > > static int single_step_handler(unsigned long unused, unsigned int esr, > > diff --git a/arch/arm64/kernel/entry-common.c b/arch/arm64/kernel/entry-common.c > > index d3be9dbf5490..65ed01606480 100644 > > --- a/arch/arm64/kernel/entry-common.c > > +++ b/arch/arm64/kernel/entry-common.c > > @@ -22,7 +22,6 @@ static void notrace el1_abort(struct pt_regs *regs, unsigned long esr) > > unsigned long far = read_sysreg(far_el1); > > > > local_daif_inherit(regs); > > - far = untagged_addr(far); > > do_mem_abort(far, esr, regs); > > } > > NOKPROBE_SYMBOL(el1_abort); > > @@ -104,7 +103,6 @@ static void notrace el0_da(struct pt_regs *regs, unsigned long esr) > > > > user_exit_irqoff(); > > local_daif_restore(DAIF_PROCCTX); > > - far = untagged_addr(far); > > do_mem_abort(far, esr, regs); > > } > > NOKPROBE_SYMBOL(el0_da); > > diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c > > index d8ebfd813e28..c73312064220 100644 > > --- a/arch/arm64/kernel/ptrace.c > > +++ b/arch/arm64/kernel/ptrace.c > > @@ -197,7 +197,7 @@ static void ptrace_hbptriggered(struct perf_event *bp, > > } > > #endif > > arm64_force_sig_fault(SIGTRAP, TRAP_HWBKPT, > > - (void __user *)(bkpt->trigger), > > + (void __user *)(bkpt->trigger), 0, 0, > > desc); > > } > > > > diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c > > index 13ebd5ca2070..c945c5cc1312 100644 > > --- a/arch/arm64/kernel/traps.c > > +++ b/arch/arm64/kernel/traps.c > > @@ -235,20 +235,25 @@ static void arm64_show_signal(int signo, const char *str) > > } > > > > void arm64_force_sig_fault(int signo, int code, void __user *addr, > > + unsigned long far, unsigned char far_tb_mask, > > const char *str) > > { > > + unsigned long ignored_bits_mask = ((unsigned long)far_tb_mask) << 56; > > + > > arm64_show_signal(signo, str); > > if (signo == SIGKILL) > > force_sig(SIGKILL); > > else > > - force_sig_fault(signo, code, addr); > > + force_sig_fault_with_ignored_bits(signo, code, addr, > > + far & ignored_bits_mask, > > + ignored_bits_mask); > > } > > > > void arm64_force_sig_mceerr(int code, void __user *addr, short lsb, > > - const char *str) > > + unsigned long far, const char *str) > > { > > arm64_show_signal(SIGBUS, str); > > - force_sig_mceerr(code, addr, lsb); > > + force_sig_mceerr(code, addr, lsb, far & (0xffUL << 56), 0xffUL << 56); > > } > > > > void arm64_force_sig_ptrace_errno_trap(int errno, void __user *addr, > > @@ -267,7 +272,7 @@ void arm64_notify_die(const char *str, struct pt_regs *regs, > > current->thread.fault_address = 0; > > current->thread.fault_code = err; > > > > - arm64_force_sig_fault(signo, sicode, addr, str); > > + arm64_force_sig_fault(signo, sicode, addr, 0, 0, str); > > } else { > > die(str, regs, err); > > } > > @@ -829,7 +834,7 @@ void bad_el0_sync(struct pt_regs *regs, int reason, unsigned int esr) > > current->thread.fault_address = 0; > > current->thread.fault_code = esr; > > > > - arm64_force_sig_fault(SIGILL, ILL_ILLOPC, pc, > > + arm64_force_sig_fault(SIGILL, ILL_ILLOPC, pc, 0, 0, > > "Bad EL0 synchronous exception"); > > } > > > > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > > index f07333e86c2f..82f05644417e 100644 > > --- a/arch/arm64/mm/fault.c > > +++ b/arch/arm64/mm/fault.c > > @@ -40,7 +40,7 @@ > > #include <asm/traps.h> > > > > struct fault_info { > > - int (*fn)(unsigned long addr, unsigned int esr, > > + int (*fn)(unsigned long far, unsigned int esr, > > struct pt_regs *regs); > > int sig; > > int code; > > @@ -383,8 +383,11 @@ static void set_thread_esr(unsigned long address, unsigned int esr) > > current->thread.fault_code = esr; > > } > > > > -static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *regs) > > +static void do_bad_area(unsigned long far, unsigned int esr, > > + struct pt_regs *regs) > > { > > + unsigned long addr = untagged_addr(far); > > + > > /* > > * If we are in kernel mode at this point, we have no context to > > * handle this fault with. > > @@ -394,7 +397,7 @@ static void do_bad_area(unsigned long addr, unsigned int esr, struct pt_regs *re > > > > set_thread_esr(addr, esr); > > arm64_force_sig_fault(inf->sig, inf->code, (void __user *)addr, > > - inf->name); > > + far, 0xff, inf->name); > > } else { > > __do_kernel_fault(addr, esr, regs); > > } > > @@ -446,7 +449,7 @@ static bool is_write_abort(unsigned int esr) > > return (esr & ESR_ELx_WNR) && !(esr & ESR_ELx_CM); > > } > > > > -static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, > > +static int __kprobes do_page_fault(unsigned long far, unsigned int esr, > > struct pt_regs *regs) > > { > > const struct fault_info *inf; > > @@ -454,6 +457,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, > > vm_fault_t fault; > > unsigned long vm_flags = VM_ACCESS_FLAGS; > > unsigned int mm_flags = FAULT_FLAG_DEFAULT; > > + unsigned long addr = untagged_addr(far); > > > > if (kprobe_page_fault(regs, esr)) > > return 0; > > @@ -566,7 +570,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, > > * this page fault. > > */ > > arm64_force_sig_fault(SIGBUS, BUS_ADRERR, (void __user *)addr, > > - inf->name); > > + far, 0xff, inf->name); > > } else if (fault & (VM_FAULT_HWPOISON_LARGE | VM_FAULT_HWPOISON)) { > > unsigned int lsb; > > > > @@ -575,7 +579,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, > > lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); > > > > arm64_force_sig_mceerr(BUS_MCEERR_AR, (void __user *)addr, lsb, > > - inf->name); > > + far, inf->name); > > } else { > > /* > > * Something tried to access memory that isn't in our memory > > @@ -583,8 +587,7 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, > > */ > > arm64_force_sig_fault(SIGSEGV, > > fault == VM_FAULT_BADACCESS ? SEGV_ACCERR : SEGV_MAPERR, > > - (void __user *)addr, > > - inf->name); > > + (void __user *)addr, far, 0xff, inf->name); > > } > > > > return 0; > > @@ -594,30 +597,32 @@ static int __kprobes do_page_fault(unsigned long addr, unsigned int esr, > > return 0; > > } > > > > -static int __kprobes do_translation_fault(unsigned long addr, > > +static int __kprobes do_translation_fault(unsigned long far, > > unsigned int esr, > > struct pt_regs *regs) > > { > > + unsigned long addr = untagged_addr(far); > > + > > if (is_ttbr0_addr(addr)) > > - return do_page_fault(addr, esr, regs); > > + return do_page_fault(far, esr, regs); > > > > - do_bad_area(addr, esr, regs); > > + do_bad_area(far, esr, regs); > > return 0; > > } > > > > -static int do_alignment_fault(unsigned long addr, unsigned int esr, > > +static int do_alignment_fault(unsigned long far, unsigned int esr, > > struct pt_regs *regs) > > { > > - do_bad_area(addr, esr, regs); > > + do_bad_area(far, esr, regs); > > return 0; > > } > > > > -static int do_bad(unsigned long addr, unsigned int esr, struct pt_regs *regs) > > +static int do_bad(unsigned long far, unsigned int esr, struct pt_regs *regs) > > { > > return 1; /* "fault" */ > > } > > > > -static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs) > > +static int do_sea(unsigned long far, unsigned int esr, struct pt_regs *regs) > > { > > const struct fault_info *inf; > > void __user *siaddr; > > @@ -635,7 +640,7 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs) > > if (esr & ESR_ELx_FnV) > > siaddr = NULL; > > else > > - siaddr = (void __user *)addr; > > + siaddr = (void __user *)untagged_addr(far); > > arm64_notify_die(inf->name, regs, inf->sig, inf->code, siaddr, esr); > > > > return 0; > > @@ -708,11 +713,12 @@ static const struct fault_info fault_info[] = { > > { do_bad, SIGKILL, SI_KERNEL, "unknown 63" }, > > }; > > > > -void do_mem_abort(unsigned long addr, unsigned int esr, struct pt_regs *regs) > > +void do_mem_abort(unsigned long far, unsigned int esr, struct pt_regs *regs) > > { > > const struct fault_info *inf = esr_to_fault_info(esr); > > + unsigned long addr = untagged_addr(far); > > > > - if (!inf->fn(addr, esr, regs)) > > + if (!inf->fn(far, esr, regs)) > > return; > > > > if (!user_mode(regs)) { > > @@ -721,8 +727,8 @@ void do_mem_abort(unsigned long addr, unsigned int esr, struct pt_regs *regs) > > show_pte(addr); > > } > > > > - arm64_notify_die(inf->name, regs, > > - inf->sig, inf->code, (void __user *)addr, esr); > > + arm64_notify_die(inf->name, regs, inf->sig, inf->code, > > + (void __user *)addr, esr); > > } > > NOKPROBE_SYMBOL(do_mem_abort); > > > > @@ -735,8 +741,8 @@ NOKPROBE_SYMBOL(do_el0_irq_bp_hardening); > > > > void do_sp_pc_abort(unsigned long addr, unsigned int esr, struct pt_regs *regs) > > { > > - arm64_notify_die("SP/PC alignment exception", regs, > > - SIGBUS, BUS_ADRALN, (void __user *)addr, esr); > > + arm64_notify_die("SP/PC alignment exception", regs, SIGBUS, BUS_ADRALN, > > + (void __user *)addr, esr); > > } > > NOKPROBE_SYMBOL(do_sp_pc_abort); > > > > @@ -862,8 +868,8 @@ void do_debug_exception(unsigned long addr_if_watchpoint, unsigned int esr, > > arm64_apply_bp_hardening(); > > > > if (inf->fn(addr_if_watchpoint, esr, regs)) { > > - arm64_notify_die(inf->name, regs, > > - inf->sig, inf->code, (void __user *)pc, esr); > > + arm64_notify_die(inf->name, regs, inf->sig, inf->code, > > + (void __user *)pc, esr); > > } > > > > debug_exception_exit(regs); > > diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c > > index 38aa07ccdbcc..73a181c904b0 100644 > > --- a/arch/mips/kernel/traps.c > > +++ b/arch/mips/kernel/traps.c > > @@ -775,7 +775,7 @@ void force_fcr31_sig(unsigned long fcr31, void __user *fault_addr, > > else if (fcr31 & FPU_CSR_INE_X) > > si_code = FPE_FLTRES; > > > > - force_sig_fault_to_task(SIGFPE, si_code, fault_addr, tsk); > > + force_sig_fault_to_task(SIGFPE, si_code, fault_addr, 0, 0, tsk); > > } > > > > int process_fpemu_return(int sig, void __user *fault_addr, unsigned long fcr31) > > diff --git a/arch/parisc/kernel/ptrace.c b/arch/parisc/kernel/ptrace.c > > index 2127974982df..62c8bb0d7d31 100644 > > --- a/arch/parisc/kernel/ptrace.c > > +++ b/arch/parisc/kernel/ptrace.c > > @@ -89,7 +89,7 @@ void user_enable_single_step(struct task_struct *task) > > parent know something happened. */ > > force_sig_fault_to_task(SIGTRAP, TRAP_TRACE, > > (void __user *) (task_regs(task)->iaoq[0] & ~3), > > - task); > > + 0, 0, task); > > /* notify_parent(task, SIGCHLD); */ > > return; > > } > > diff --git a/arch/parisc/mm/fault.c b/arch/parisc/mm/fault.c > > index 4bfe2da9fbe3..2a6064ea2dfc 100644 > > --- a/arch/parisc/mm/fault.c > > +++ b/arch/parisc/mm/fault.c > > @@ -400,7 +400,7 @@ void do_page_fault(struct pt_regs *regs, unsigned long code, > > lsb = PAGE_SHIFT; > > > > force_sig_mceerr(BUS_MCEERR_AR, (void __user *) address, > > - lsb); > > + lsb, 0, 0); > > return; > > } > > #endif > > diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c > > index 0add963a849b..4ffe2fb8e31a 100644 > > --- a/arch/powerpc/mm/fault.c > > +++ b/arch/powerpc/mm/fault.c > > @@ -152,7 +152,7 @@ static int do_sigbus(struct pt_regs *regs, unsigned long address, > > if (fault & VM_FAULT_HWPOISON) > > lsb = PAGE_SHIFT; > > > > - force_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb); > > + force_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb, 0, 0); > > return 0; > > } > > > > diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c > > index 35f1498e9832..a443eec157f6 100644 > > --- a/arch/x86/mm/fault.c > > +++ b/arch/x86/mm/fault.c > > @@ -898,7 +898,8 @@ do_sigbus(struct pt_regs *regs, unsigned long error_code, unsigned long address, > > lsb = hstate_index_to_shift(VM_FAULT_GET_HINDEX(fault)); > > if (fault & VM_FAULT_HWPOISON) > > lsb = PAGE_SHIFT; > > - force_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb); > > + force_sig_mceerr(BUS_MCEERR_AR, (void __user *)address, lsb, 0, > > + 0); > > return; > > } > > #endif > > diff --git a/include/linux/compat.h b/include/linux/compat.h > > index 55d4228dfd88..273146cf30fd 100644 > > --- a/include/linux/compat.h > > +++ b/include/linux/compat.h > > @@ -234,6 +234,8 @@ typedef struct compat_siginfo { > > compat_uptr_t _pad[6]; > > }; > > compat_uptr_t _xflags; > > + compat_uptr_t _addr_ignored_bits; > > + compat_uptr_t _addr_ignored_bits_mask; > > } _sigfault; > > > > /* SIGPOLL */ > > diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h > > index 1bad18a1d8ba..f62a014a5a4d 100644 > > --- a/include/linux/sched/signal.h > > +++ b/include/linux/sched/signal.h > > @@ -311,16 +311,24 @@ static inline void kernel_signal_stop(void) > > int force_sig_fault_to_task(int sig, int code, void __user *addr > > ___ARCH_SI_TRAPNO(int trapno) > > ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) > > - , struct task_struct *t); > > + , unsigned long addr_ignored_bits, unsigned long addr_ignored_bits_mask, > > + struct task_struct *t); > > int force_sig_fault(int sig, int code, void __user *addr > > ___ARCH_SI_TRAPNO(int trapno) > > ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)); > > +int force_sig_fault_with_ignored_bits(int sig, int code, void __user *addr > > + ___ARCH_SI_TRAPNO(int trapno) > > + ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) > > + , unsigned long addr_ignored_bits, > > + unsigned long addr_ignored_bits_mask); > > int send_sig_fault(int sig, int code, void __user *addr > > ___ARCH_SI_TRAPNO(int trapno) > > ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) > > , struct task_struct *t); > > > > -int force_sig_mceerr(int code, void __user *, short); > > +int force_sig_mceerr(int code, void __user *addr, short addr_lsb, > > + unsigned long addr_ignored_bits, > > + unsigned long addr_ignored_bits_mask); > > int send_sig_mceerr(int code, void __user *, short, struct task_struct *); > > > > int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper); > > diff --git a/include/uapi/asm-generic/siginfo.h b/include/uapi/asm-generic/siginfo.h > > index 413d804623c0..1fc6482b0ad4 100644 > > --- a/include/uapi/asm-generic/siginfo.h > > +++ b/include/uapi/asm-generic/siginfo.h > > @@ -94,6 +94,8 @@ union __sifields { > > void *_pad[6]; > > }; > > unsigned long _xflags; > > + unsigned long _addr_ignored_bits; > > + unsigned long _addr_ignored_bits_mask; > > } _sigfault; > > > > /* SIGPOLL */ > > @@ -155,6 +157,8 @@ typedef struct siginfo { > > #endif > > #define si_addr_lsb _sifields._sigfault._addr_lsb > > #define si_xflags _sifields._sigfault._xflags > > +#define si_addr_ignored_bits _sifields._sigfault._addr_ignored_bits > > +#define si_addr_ignored_bits_mask _sifields._sigfault._addr_ignored_bits_mask > > #define si_lower _sifields._sigfault._addr_bnd._lower > > #define si_upper _sifields._sigfault._addr_bnd._upper > > #define si_pkey _sifields._sigfault._addr_pkey._pkey > > @@ -295,6 +299,12 @@ typedef struct siginfo { > > #define EMT_TAGOVF 1 /* tag overflow */ > > #define NSIGEMT 1 > > > > +/* > > + * SIGILL, SIGFPE, SIGSEGV, SIGBUS, SIGTRAP, SIGEMT si_xflags > > + */ > > +#define SI_XFLAG_IGNORED_BITS 1 > > +/* si_addr_ignored_bits{,_mask} fields valid */ > > + > > /* > > * sigevent definitions > > * > > diff --git a/kernel/signal.c b/kernel/signal.c > > index 72182eed1b8d..1f1e42adc57d 100644 > > --- a/kernel/signal.c > > +++ b/kernel/signal.c > > @@ -1652,7 +1652,8 @@ void force_sigsegv(int sig) > > int force_sig_fault_to_task(int sig, int code, void __user *addr > > ___ARCH_SI_TRAPNO(int trapno) > > ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr) > > - , struct task_struct *t) > > + , unsigned long addr_ignored_bits, unsigned long addr_ignored_bits_mask, > > + struct task_struct *t) > > { > > struct kernel_siginfo info; > > > > @@ -1669,17 +1670,32 @@ int force_sig_fault_to_task(int sig, int code, void __user *addr > > info.si_flags = flags; > > info.si_isr = isr; > > #endif > > - info.si_xflags = 0; > > + info.si_xflags = SI_XFLAG_IGNORED_BITS; > > + info.si_addr_ignored_bits = addr_ignored_bits; > > + info.si_addr_ignored_bits_mask = addr_ignored_bits_mask; > > return force_sig_info_to_task(&info, t); > > } > > > > -int force_sig_fault(int sig, int code, void __user *addr > > +int force_sig_fault_with_ignored_bits(int sig, int code, void __user *addr > > ___ARCH_SI_TRAPNO(int trapno) > > - ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)) > > + ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr), > > + unsigned long addr_ignored_bits, unsigned long addr_ignored_bits_mask) > > { > > return force_sig_fault_to_task(sig, code, addr > > ___ARCH_SI_TRAPNO(trapno) > > - ___ARCH_SI_IA64(imm, flags, isr), current); > > + ___ARCH_SI_IA64(imm, flags, isr), > > + addr_ignored_bits, > > + addr_ignored_bits_mask, current); > > +} > > + > > +int force_sig_fault(int sig, int code, void __user *addr > > + ___ARCH_SI_TRAPNO(int trapno) > > + ___ARCH_SI_IA64(int imm, unsigned int flags, unsigned long isr)) > > +{ > > + return force_sig_fault_with_ignored_bits(sig, code, addr > > + ___ARCH_SI_TRAPNO(trapno) > > + ___ARCH_SI_IA64(imm, flags, > > + isr), 0, 0); > > } > > > > int send_sig_fault(int sig, int code, void __user *addr > > @@ -1706,7 +1722,9 @@ int send_sig_fault(int sig, int code, void __user *addr > > return send_sig_info(info.si_signo, &info, t); > > } > > > > -int force_sig_mceerr(int code, void __user *addr, short lsb) > > +int force_sig_mceerr(int code, void __user *addr, short lsb, > > + unsigned long addr_ignored_bits, > > + unsigned long addr_ignored_bits_mask) > > Rather than having to pass these extra arguments all over the place, can > we just pass the far for addr, and have an arch-specific hook for > splitting the ignored from non-ignored bits. For now at least, I expect > that ignored bits mask to be constant for a given platform and kernel. That sounds like a good idea. I think that for MTE we will want to make it conditional on the si_code (so SEGV_MTESERR would get 0xf << 56 while everything else would get 0xff << 56) so I can hook that up at the same time. > > { > > struct kernel_siginfo info; > > > > @@ -1717,7 +1735,9 @@ int force_sig_mceerr(int code, void __user *addr, short lsb) > > info.si_code = code; > > info.si_addr = addr; > > info.si_addr_lsb = lsb; > > - info.si_xflags = 0; > > + info.si_xflags = SI_XFLAG_IGNORED_BITS; > > Maybe drop the first _, so that this becomes > > SIXFLAG_IGNORED_BITS > > ? This may help to avoid anyone thinking this might be an si_code > value. Maybe ..._IGNORED_ADDR_BITS would also help make it clearer what > this bit is referring to. Yes, it should have been spelled the same way as the field name (i.e. SIXFLAG_ADDR_IGNORED_BITS), that was my mistake. I don't have a strong opinion on whether to keep the underscore in the middle or not. > > + info.si_addr_ignored_bits = addr_ignored_bits; > > + info.si_addr_ignored_bits_mask = addr_ignored_bits_mask; > > return force_sig_info(&info); > > } > > > > @@ -3298,6 +3318,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to, > > to->si_trapno = from->si_trapno; > > #endif > > to->si_xflags = from->si_xflags; > > + to->si_addr_ignored_bits = from->si_addr_ignored_bits; > > + to->si_addr_ignored_bits_mask = from->si_addr_ignored_bits_mask; > > break; > > case SIL_FAULT_MCEERR: > > to->si_addr = ptr_to_compat(from->si_addr); > > @@ -3306,6 +3328,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to, > > #endif > > to->si_addr_lsb = from->si_addr_lsb; > > to->si_xflags = from->si_xflags; > > + to->si_addr_ignored_bits = from->si_addr_ignored_bits; > > + to->si_addr_ignored_bits_mask = from->si_addr_ignored_bits_mask; > > break; > > case SIL_FAULT_BNDERR: > > to->si_addr = ptr_to_compat(from->si_addr); > > @@ -3315,6 +3339,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to, > > to->si_lower = ptr_to_compat(from->si_lower); > > to->si_upper = ptr_to_compat(from->si_upper); > > to->si_xflags = from->si_xflags; > > + to->si_addr_ignored_bits = from->si_addr_ignored_bits; > > + to->si_addr_ignored_bits_mask = from->si_addr_ignored_bits_mask; > > break; > > case SIL_FAULT_PKUERR: > > to->si_addr = ptr_to_compat(from->si_addr); > > @@ -3323,6 +3349,8 @@ void copy_siginfo_to_external32(struct compat_siginfo *to, > > #endif > > to->si_pkey = from->si_pkey; > > to->si_xflags = from->si_xflags; > > + to->si_addr_ignored_bits = from->si_addr_ignored_bits; > > + to->si_addr_ignored_bits_mask = from->si_addr_ignored_bits_mask; > > break;> case SIL_CHLD: > > to->si_pid = from->si_pid; > > @@ -3382,6 +3410,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to, > > to->si_trapno = from->si_trapno; > > #endif > > to->si_xflags = from->si_xflags; > > + to->si_addr_ignored_bits = from->si_addr_ignored_bits; > > + to->si_addr_ignored_bits_mask = from->si_addr_ignored_bits_mask; > > break; > > case SIL_FAULT_MCEERR: > > to->si_addr = compat_ptr(from->si_addr); > > @@ -3390,6 +3420,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to, > > #endif > > to->si_addr_lsb = from->si_addr_lsb; > > to->si_xflags = from->si_xflags; > > + to->si_addr_ignored_bits = from->si_addr_ignored_bits; > > + to->si_addr_ignored_bits_mask = from->si_addr_ignored_bits_mask; > > break; > > case SIL_FAULT_BNDERR: > > to->si_addr = compat_ptr(from->si_addr); > > @@ -3399,6 +3431,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to, > > to->si_lower = compat_ptr(from->si_lower); > > to->si_upper = compat_ptr(from->si_upper); > > to->si_xflags = from->si_xflags; > > + to->si_addr_ignored_bits = from->si_addr_ignored_bits; > > + to->si_addr_ignored_bits_mask = from->si_addr_ignored_bits_mask; > > break; > > case SIL_FAULT_PKUERR: > > to->si_addr = compat_ptr(from->si_addr); > > @@ -3407,6 +3441,8 @@ static int post_copy_siginfo_from_user32(kernel_siginfo_t *to, > > #endif > > to->si_pkey = from->si_pkey; > > to->si_xflags = from->si_xflags; > > + to->si_addr_ignored_bits = from->si_addr_ignored_bits; > > + to->si_addr_ignored_bits_mask = from->si_addr_ignored_bits_mask; > > Again, can you justify why this is exhaustive? If there any way to > factor this so as to reduce the number of places we need to hack this > in? Addressed on the other patch. Once I've factored the various SIL_FAULT* cases there should be only a handful of places requiring changes. Peter
