On 9/17/20 3:03 PM, Catalin Marinas wrote:

On Tue, Sep 15, 2020 at 11:16:06PM +0200, Andrey Konovalov wrote:

quoted

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index a3bd189602df..cdc23662691c 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c

@@ -294,6 +295,18 @@ 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)
 {

@@ -641,10 +654,31 @@ static int do_sea(unsigned long addr, unsigned int esr, struct pt_regs *regs)
 	return 0;
 }
 
+static void do_tag_recovery(unsigned long addr, unsigned int esr,
+			   struct pt_regs *regs)
+{
+	report_tag_fault(addr, esr, regs);

I'd only report this once since we expect it to be disabled lazily on
the other CPUs (i.e. just use a "static bool reported" to keep track).

Ok, I will fix it in the next version.

quoted

+
+	/*
+	 * Disable Memory Tagging Extension Tag Checking on the local CPU

Too verbose, just say MTE tag checking, people reading this code should
have learnt already what MTE stands for ;).

All right, will change it ;)

quoted

+	 * for the current EL.
+	 * It will be done lazily on the other CPUs when they will hit a
+	 * tag fault.
+	 */
+	sysreg_clear_set(sctlr_el1, SCTLR_ELx_TCF_MASK, SCTLR_ELx_TCF_NONE);
+	isb();
+}
+
+
 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);

This part looks fine now.

Ok, thanks.

-- 
Regards,
Vincenzo

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