linux-kernel - [PATCH 4/4] x86/mm: Unexport __cachemode2pte

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Date:   Wed,  8 Apr 2020 17:27:45 +0200
From:   Christoph Hellwig <hch@....de>
To:     x86@...nel.org, Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH 4/4] x86/mm: Unexport __cachemode2pte_tbl

Exporting the raw data for a table is generally a bad idea.  Move
cachemode2protval out of line given that it isn't really used in the
fast path, and then mark __cachemode2pte_tbl static.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 arch/x86/include/asm/pgtable_types.h | 14 ++------------
 arch/x86/mm/init.c                   | 11 +++++++++--
 arch/x86/mm/pat/set_memory.c         |  5 +++++
 3 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h
index a3b78d84b26a..567abdbd64d3 100644
--- a/arch/x86/include/asm/pgtable_types.h
+++ b/arch/x86/include/asm/pgtable_types.h
@@ -467,8 +467,6 @@ static inline pteval_t pte_flags(pte_t pte)
 	return native_pte_val(pte) & PTE_FLAGS_MASK;
 }
 
-extern uint16_t __cachemode2pte_tbl[_PAGE_CACHE_MODE_NUM];
-
 #define __pte2cm_idx(cb)				\
 	((((cb) >> (_PAGE_BIT_PAT - 2)) & 4) |		\
 	 (((cb) >> (_PAGE_BIT_PCD - 1)) & 2) |		\
@@ -478,16 +476,8 @@ extern uint16_t __cachemode2pte_tbl[_PAGE_CACHE_MODE_NUM];
 	 (((i) & 2) << (_PAGE_BIT_PCD - 1)) |		\
 	 (((i) & 1) << _PAGE_BIT_PWT))
 
-static inline unsigned long cachemode2protval(enum page_cache_mode pcm)
-{
-	if (likely(pcm == 0))
-		return 0;
-	return __cachemode2pte_tbl[pcm];
-}
-static inline pgprot_t cachemode2pgprot(enum page_cache_mode pcm)
-{
-	return __pgprot(cachemode2protval(pcm));
-}
+unsigned long cachemode2protval(enum page_cache_mode pcm);
+
 static inline unsigned long protval_4k_2_large(unsigned long val)
 {
 	return (val & ~(_PAGE_PAT | _PAGE_PAT_LARGE)) |
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c
index 8482ee51b225..4a8d0d67e729 100644
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -49,7 +49,7 @@
  *   Index into __pte2cachemode_tbl[] are the caching attribute bits of the pte
  *   (_PAGE_PWT, _PAGE_PCD, _PAGE_PAT) at index bit positions 0, 1, 2.
  */
-uint16_t __cachemode2pte_tbl[_PAGE_CACHE_MODE_NUM] = {
+static uint16_t __cachemode2pte_tbl[_PAGE_CACHE_MODE_NUM] = {
 	[_PAGE_CACHE_MODE_WB      ]	= 0         | 0        ,
 	[_PAGE_CACHE_MODE_WC      ]	= 0         | _PAGE_PCD,
 	[_PAGE_CACHE_MODE_UC_MINUS]	= 0         | _PAGE_PCD,
@@ -57,7 +57,14 @@ uint16_t __cachemode2pte_tbl[_PAGE_CACHE_MODE_NUM] = {
 	[_PAGE_CACHE_MODE_WT      ]	= 0         | _PAGE_PCD,
 	[_PAGE_CACHE_MODE_WP      ]	= 0         | _PAGE_PCD,
 };
-EXPORT_SYMBOL(__cachemode2pte_tbl);
+
+unsigned long cachemode2protval(enum page_cache_mode pcm)
+{
+	if (likely(pcm == 0))
+		return 0;
+	return __cachemode2pte_tbl[pcm];
+}
+EXPORT_SYMBOL(cachemode2protval);
 
 static uint8_t __pte2cachemode_tbl[8] = {
 	[__pte2cm_idx( 0        | 0         | 0        )] = _PAGE_CACHE_MODE_WB,
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 6d5424069e2b..b8ee3f4e8202 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -68,6 +68,11 @@ static DEFINE_SPINLOCK(cpa_lock);
 #define CPA_PAGES_ARRAY 4
 #define CPA_NO_CHECK_ALIAS 8 /* Do not search for aliases */
 
+static inline pgprot_t cachemode2pgprot(enum page_cache_mode pcm)
+{
+	return __pgprot(cachemode2protval(pcm));
+}
+
 #ifdef CONFIG_PROC_FS
 static unsigned long direct_pages_count[PG_LEVEL_NUM];
 
-- 
2.25.1