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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Aug 14, 2020 at 07:27:03PM +0200, Andrey Konovalov wrote: > diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c > index 5e832b3387f1..c62c8ba85c0e 100644 > --- a/arch/arm64/mm/fault.c > +++ b/arch/arm64/mm/fault.c > @@ -33,6 +33,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -222,6 +223,20 @@ int ptep_set_access_flags(struct vm_area_struct *vma, > return 1; > } > > +static bool is_el1_mte_sync_tag_check_fault(unsigned int esr) > +{ > + unsigned int ec = ESR_ELx_EC(esr); > + unsigned int fsc = esr & ESR_ELx_FSC; > + > + if (ec != ESR_ELx_EC_DABT_CUR) > + return false; > + > + if (fsc == ESR_ELx_FSC_MTE) > + return true; > + > + return false; > +} > + > static bool is_el1_instruction_abort(unsigned int esr) > { > return ESR_ELx_EC(esr) == ESR_ELx_EC_IABT_CUR; > @@ -294,6 +309,18 @@ static void die_kernel_fault(const char *msg, unsigned long addr, > do_exit(SIGKILL); > } > > +static void report_tag_fault(unsigned long addr, unsigned int esr, > + struct pt_regs *regs) > +{ > + bool is_write = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0; > + > + pr_alert("Memory Tagging Extension Fault in %pS\n", (void *)regs->pc); > + pr_alert(" %s at address %lx\n", is_write ? "Write" : "Read", addr); > + pr_alert(" Pointer tag: [%02x], memory tag: [%02x]\n", > + mte_get_ptr_tag(addr), > + mte_get_mem_tag((void *)addr)); > +} > + > static void __do_kernel_fault(unsigned long addr, unsigned int esr, > struct pt_regs *regs) > { > @@ -317,12 +344,16 @@ static void __do_kernel_fault(unsigned long addr, unsigned int esr, > msg = "execute from non-executable memory"; > else > msg = "read from unreadable memory"; > + } else if (is_el1_mte_sync_tag_check_fault(esr)) { > + report_tag_fault(addr, esr, regs); > + msg = "memory tagging extension fault"; IIUC, that's dead code. See my comment below on do_tag_check_fault(). > } else if (addr < PAGE_SIZE) { > msg = "NULL pointer dereference"; > } else { > msg = "paging request"; > } > > + Unnecessary empty line. > die_kernel_fault(msg, addr, esr, regs); > } > > @@ -658,10 +689,27 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs) > return 0; > } > > +static int do_tag_recovery(unsigned long addr, unsigned int esr, > + struct pt_regs *regs) > +{ > + report_tag_fault(addr, esr, regs); > + > + /* Skip over the faulting instruction and continue: */ > + arm64_skip_faulting_instruction(regs, AARCH64_INSN_SIZE); Ooooh, do we expect the kernel to still behave correctly after this? I thought the recovery means disabling tag checking altogether and restarting the instruction rather than skipping over it. We only skip if we emulated it. > + > + return 0; > +} > + > + > static int do_tag_check_fault(unsigned long addr, unsigned int esr, > struct pt_regs *regs) > { > - do_bad_area(addr, esr, regs); > + /* The tag check fault (TCF) is per TTBR */ > + if (is_ttbr0_addr(addr)) > + do_bad_area(addr, esr, regs); > + else > + do_tag_recovery(addr, esr, regs); So we never invoke __do_kernel_fault() for a synchronous tag check in the kernel. What's with all the is_el1_mte_sync_tag_check_fault() check above? -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel