linux-kernel - [PATCH v3 13/13] MIPS: mm: Panic if an XPA kernel is run without RIXI

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Message-ID: <1461054311-387-14-git-send-email-paul.burton@imgtec.com>
Date:	Tue, 19 Apr 2016 09:25:11 +0100
From:	Paul Burton <paul.burton@...tec.com>
To:	<linux-mips@...ux-mips.org>, Ralf Baechle <ralf@...ux-mips.org>
CC:	James Hogan <james.hogan@...tec.com>,
	Paul Burton <paul.burton@...tec.com>,
	Paul Gortmaker <paul.gortmaker@...driver.com>,
	<linux-kernel@...r.kernel.org>
Subject: [PATCH v3 13/13] MIPS: mm: Panic if an XPA kernel is run without RIXI

XPA kernels hardcode for the presence of RIXI - the PTE format & its
handling presume RI & XI bits. Make this dependence explicit by panicing
if we run on a system that violates it.

Signed-off-by: Paul Burton <paul.burton@...tec.com>
Reviewed-by: James Hogan <james.hogan@...tec.com>

---

Changes in v3:
- Remove newline in panic() call.

Changes in v2:
- New patch, in response to clarification on patch 5.

 arch/mips/mm/tlbex.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 3f1a8a2..2afc710 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -2395,6 +2395,9 @@ void build_tlb_refill_handler(void)
 	 */
 	static int run_once = 0;
 
+	if (config_enabled(CONFIG_XPA) && !cpu_has_rixi)
+		panic("Kernels supporting XPA currently require CPUs with RIXI");
+
 	output_pgtable_bits_defines();
 	check_pabits();
 
-- 
2.8.0