linux-kernel - [PATCH] Revert "MIPS: mm: tlbex: Use cpu_has_mips_r2_exec

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Message-Id: <1424731974-27926-1-git-send-email-ddaney.cavm@gmail.com>
Date:	Mon, 23 Feb 2015 14:52:54 -0800
From:	David Daney <ddaney.cavm@...il.com>
To:	linux-mips@...ux-mips.org, ralf@...ux-mips.org
Cc:	linux-kernel@...r.kernel.org,
	Leonid Yegoshin <Leonid.Yegoshin@...tec.com>,
	Markos Chandras <markos.chandras@...tec.com>,
	David Daney <david.daney@...ium.com>
Subject: [PATCH] Revert "MIPS: mm: tlbex: Use cpu_has_mips_r2_exec_hazard for the EHB instruction"

From: David Daney <david.daney@...ium.com>

This reverts commit 77f3ee59ee7cfe19e0ee48d9a990c7967fbfcbed.

There are two problems:

1) It breaks OCTEON, which will now crash in early boot with:

  Kernel panic - not syncing: No TLB refill handler yet (CPU type: 80)

2) The logic is broken.

The meaning of cpu_has_mips_r2_exec_hazard is that the EHB instruction
is required.  The offending patch attempts (and fails) to change the
meaning to be that EHB is part of the ISA.

Signed-off-by: David Daney <david.daney@...ium.com>
---
 arch/mips/mm/tlbex.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index d75ff73..ff8d99c 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -501,7 +501,7 @@ static void build_tlb_write_entry(u32 **p, struct uasm_label **l,
 	case tlb_indexed: tlbw = uasm_i_tlbwi; break;
 	}
 
-	if (cpu_has_mips_r2_exec_hazard) {
+	if (cpu_has_mips_r2) {
 		/*
 		 * The architecture spec says an ehb is required here,
 		 * but a number of cores do not have the hazard and
@@ -1953,7 +1953,7 @@ static void build_r4000_tlb_load_handler(void)
 
 		switch (current_cpu_type()) {
 		default:
-			if (cpu_has_mips_r2_exec_hazard) {
+			if (cpu_has_mips_r2) {
 				uasm_i_ehb(&p);
 
 		case CPU_CAVIUM_OCTEON:
@@ -2020,7 +2020,7 @@ static void build_r4000_tlb_load_handler(void)
 
 		switch (current_cpu_type()) {
 		default:
-			if (cpu_has_mips_r2_exec_hazard) {
+			if (cpu_has_mips_r2) {
 				uasm_i_ehb(&p);
 
 		case CPU_CAVIUM_OCTEON:
-- 
1.7.11.7

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