Re: [PATCH v17 1/1] arm64: mm: Handle Granule Protection Faults (GPFs)

On 10/09/2026 18:45, Catalin Marinas wrote:

On Mon, Sep 07, 2026 at 05:22:04PM +0100, Suzuki K Poulose wrote:

quoted

diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
index 0b52557652be6..ad00997b1a873 100644
--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c

@@ -910,6 +910,22 @@ static int do_tag_check_fault(unsigned long far, unsigned long esr,
  	return 0;
  }
  
+static int do_gpf_ptw(unsigned long far, unsigned long esr, struct pt_regs *regs)
+{
+	const struct fault_info *inf = esr_to_fault_info(esr);
+
+	die_kernel_fault(inf->name, far, esr, regs);
+	return 0;
+}
+
+static int do_gpf(unsigned long far, unsigned long esr, struct pt_regs *regs)
+{
+	if (!is_el1_instruction_abort(esr) && fixup_exception(regs, esr))
+		return 0;
+
+	return 1;
+}

If we end up with a user PC here, we correctly return 1 but only because
fixup_exception() won't find the PC. I'd rather have this explicit with
a user_mode() check.

Sure, I have made the condtion to:

+       if (!user_mode(regs) && !is_el1_instruction_abort(esr) &&
+           fixup_exception(regs, esr))
+               return 0;

quoted

+
  static const struct fault_info fault_info[] = {
  	{ do_bad,		SIGKILL, SI_KERNEL,	"ttbr address size fault"	},
  	{ do_bad,		SIGKILL, SI_KERNEL,	"level 1 address size fault"	},

@@ -946,12 +962,12 @@ static const struct fault_info fault_info[] = {
  	{ do_bad,		SIGKILL, SI_KERNEL,	"unknown 32"			},
  	{ do_alignment_fault,	SIGBUS,  BUS_ADRALN,	"alignment fault"		},
  	{ do_bad,		SIGKILL, SI_KERNEL,	"unknown 34"			},
-	{ do_bad,		SIGKILL, SI_KERNEL,	"unknown 35"			},
-	{ do_bad,		SIGKILL, SI_KERNEL,	"unknown 36"			},
-	{ do_bad,		SIGKILL, SI_KERNEL,	"unknown 37"			},
-	{ do_bad,		SIGKILL, SI_KERNEL,	"unknown 38"			},
-	{ do_bad,		SIGKILL, SI_KERNEL,	"unknown 39"			},
-	{ do_bad,		SIGKILL, SI_KERNEL,	"unknown 40"			},
+	{ do_gpf_ptw,		SIGKILL, SI_KERNEL,	"level -1 granule protection fault (translation table walk)" },
+	{ do_gpf_ptw,		SIGKILL, SI_KERNEL,	"level 0 granule protection fault (translation table walk)" },
+	{ do_gpf_ptw,		SIGKILL, SI_KERNEL,	"level 1 granule protection fault (translation table walk)" },
+	{ do_gpf_ptw,		SIGKILL, SI_KERNEL,	"level 2 granule protection fault (translation table walk)" },
+	{ do_gpf_ptw,		SIGKILL, SI_KERNEL,	"level 3 granule protection fault (translation table walk)" },
+	{ do_gpf,		SIGBUS,  SI_KERNEL,	"granule protection fault" },

For SIGBUS, we should use BUS_OBJERR like we do for do_sea().

Good point, I have added that.

Otherwise it looks fine to me.

Thanks, I have already added the untagged_addr() as reported by Sashiko.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

Cheers
Suzuki