arm64: pt_regs: swap 'unused' and 'pmr' fields

In subsequent patches we'll want to add an additional u64 to struct
pt_regs. To make space, this patch swaps the 'unused' and 'pmr' fields,
as the 'pmr' value only requires bits[7:0] and can safely fit into a
u32, which frees up a 64-bit unused field.

The 'lockdep_hardirqs' and 'exit_rcu' fields should eventually be moved
out of pt_regs and managed locally within entry-common.c, so I've left
those as-is for the moment.

There should be no functional change as a result of this patch.

Signed-off-by: Mark Rutland <[email protected]>
Reviewed-by: Mark Brown <[email protected]>
Reviewed-by: Miroslav Benes <[email protected]>
Reviewed-by: Puranjay Mohan <[email protected]>
Cc: Ard Biesheuvel <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Kalesh Singh <[email protected]>
Cc: Madhavan T. Venkataraman <[email protected]>
Cc: Marc Zyngier <[email protected]>
Cc: Will Deacon <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Catalin Marinas <[email protected]>

Author: mrutland-arm

arch/arm64/include/asm/ptrace.h

@@ -163,11 +163,11 @@ struct pt_regs {
 	};
 	u64 orig_x0;
 	s32 syscallno;
-	u32 unused;
+	u32 pmr;
 
 	u64 sdei_ttbr1;
-	/* Only valid when ARM64_HAS_GIC_PRIO_MASKING is enabled. */
-	u64 pmr;
+	u64 unused;
+
 	u64 stackframe[2];
 
 	/* Only valid for some EL1 exceptions. */

arch/arm64/kernel/entry.S

@@ -315,7 +315,7 @@ alternative_if_not ARM64_HAS_GIC_PRIO_MASKING
 alternative_else_nop_endif
 
 	mrs_s	x20, SYS_ICC_PMR_EL1
-	str	x20, [sp, #S_PMR]
+	str	w20, [sp, #S_PMR]
 	mov	x20, #GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET
 	msr_s	SYS_ICC_PMR_EL1, x20
 
@@ -342,7 +342,7 @@ alternative_if_not ARM64_HAS_GIC_PRIO_MASKING
 	b	.Lskip_pmr_restore\@
 alternative_else_nop_endif
 
-	ldr	x20, [sp, #S_PMR]
+	ldr	w20, [sp, #S_PMR]
 	msr_s	SYS_ICC_PMR_EL1, x20
 
 	/* Ensure priority change is seen by redistributor */

arch/arm64/kernel/process.c

@@ -227,7 +227,7 @@ void __show_regs(struct pt_regs *regs)
 	printk("sp : %016llx\n", sp);
 
 	if (system_uses_irq_prio_masking())
-		printk("pmr: %08llx\n", regs->pmr);
+		printk("pmr: %08x\n", regs->pmr);
 
 	i = top_reg;