linux-kernel - [PATCH v2 11/13] MIPS: mm: Simplify build_update

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Date:	Mon, 18 Apr 2016 10:35:31 +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 v2 11/13] MIPS: mm: Simplify build_update_entries

We can simplify build_update_entries by unifying the code for the 36 bit
physical addressing with MIPS32 case with the general case, by using
pte_off_ variables in all cases & handling the trivial
_PAGE_GLOBAL_SHIFT == 0 case in build_convert_pte_to_entrylo. This
leaves XPA as the only special case.

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

---

Changes in v2:
- #ifdef on CONFIG_CPU_MIPS32 instead of config_enabled(CONFIG_32BIT) to avoid referencing pte_high in configurations where it doesn't exist.

 arch/mips/mm/tlbex.c | 37 ++++++++++++++++---------------------
 1 file changed, 16 insertions(+), 21 deletions(-)

diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 0bd3755..c7c14bd 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -626,6 +626,11 @@ static void build_tlb_write_entry(u32 **p, struct uasm_label **l,
 static __maybe_unused void build_convert_pte_to_entrylo(u32 **p,
 							unsigned int reg)
 {
+	if (_PAGE_GLOBAL_SHIFT == 0) {
+		/* pte_t is already in EntryLo format */
+		return;
+	}
+
 	if (cpu_has_rixi && _PAGE_NO_EXEC) {
 		if (fill_includes_sw_bits) {
 			UASM_i_ROTR(p, reg, reg, ilog2(_PAGE_GLOBAL));
@@ -1003,10 +1008,16 @@ static void build_get_ptep(u32 **p, unsigned int tmp, unsigned int ptr)
 
 static void build_update_entries(u32 **p, unsigned int tmp, unsigned int ptep)
 {
-	if (config_enabled(CONFIG_XPA)) {
-		int pte_off_even = sizeof(pte_t) / 2;
-		int pte_off_odd = pte_off_even + sizeof(pte_t);
+	int pte_off_even = 0;
+	int pte_off_odd = sizeof(pte_t);
 
+#if defined(CONFIG_CPU_MIPS32) && defined(CONFIG_PHYS_ADDR_T_64BIT)
+	/* The low 32 bits of EntryLo is stored in pte_high */
+	pte_off_even += offsetof(pte_t, pte_high);
+	pte_off_odd += offsetof(pte_t, pte_high);
+#endif
+
+	if (config_enabled(CONFIG_XPA)) {
 		uasm_i_lw(p, tmp, pte_off_even, ptep); /* even pte */
 		UASM_i_ROTR(p, tmp, tmp, ilog2(_PAGE_GLOBAL));
 		UASM_i_MTC0(p, tmp, C0_ENTRYLO0);
@@ -1025,24 +1036,8 @@ static void build_update_entries(u32 **p, unsigned int tmp, unsigned int ptep)
 		return;
 	}
 
-	/*
-	 * 64bit address support (36bit on a 32bit CPU) in a 32bit
-	 * Kernel is a special case. Only a few CPUs use it.
-	 */
-	if (config_enabled(CONFIG_PHYS_ADDR_T_64BIT) && !cpu_has_64bits) {
-		int pte_off_even = sizeof(pte_t) / 2;
-		int pte_off_odd = pte_off_even + sizeof(pte_t);
-
-		uasm_i_lw(p, tmp, pte_off_even, ptep); /* even pte */
-		UASM_i_MTC0(p, tmp, C0_ENTRYLO0);
-
-		uasm_i_lw(p, ptep, pte_off_odd, ptep); /* odd pte */
-		UASM_i_MTC0(p, ptep, C0_ENTRYLO1);
-		return;
-	}
-
-	UASM_i_LW(p, tmp, 0, ptep); /* get even pte */
-	UASM_i_LW(p, ptep, sizeof(pte_t), ptep); /* get odd pte */
+	UASM_i_LW(p, tmp, pte_off_even, ptep); /* get even pte */
+	UASM_i_LW(p, ptep, pte_off_odd, ptep); /* get odd pte */
 	if (r45k_bvahwbug())
 		build_tlb_probe_entry(p);
 	build_convert_pte_to_entrylo(p, tmp);
-- 
2.8.0