linux-kernel - [PATCH 3/3] powerpc/32: Remove __map_without

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Message-Id: <3422094db965d218c4c3d8580f526963a9ac897f.1655202721.git.christophe.leroy@csgroup.eu>
Date:   Tue, 14 Jun 2022 12:32:25 +0200
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     Christophe Leroy <christophe.leroy@...roup.eu>,
        linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 3/3] powerpc/32: Remove __map_without_ltlbs

__map_without_ltlbs is used only for 40x, and only when
STRICT_KERNEL_RWX, KFENCE or DEBUG_PAGEALLOC is active.

Do the verification directly in 40x version of mmu_mapin_ram()
and remove __map_without_ltlbs from core ppc32.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/mm/init_32.c    | 23 -----------------------
 arch/powerpc/mm/nohash/40x.c |  9 +++++++--
 2 files changed, 7 insertions(+), 25 deletions(-)

diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
index 6f2e6210c273..62d9af6606cd 100644
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -69,29 +69,9 @@ EXPORT_SYMBOL(agp_special_page);
 
 void MMU_init(void);
 
-int __map_without_ltlbs;
-
 /* max amount of low RAM to map in */
 unsigned long __max_low_memory = MAX_LOW_MEM;
 
-/*
- * Check for command-line options that affect what MMU_init will do.
- */
-static void __init MMU_setup(void)
-{
-	if (IS_ENABLED(CONFIG_PPC_8xx))
-		return;
-
-	if (IS_ENABLED(CONFIG_KFENCE))
-		__map_without_ltlbs = 1;
-
-	if (debug_pagealloc_enabled())
-		__map_without_ltlbs = 1;
-
-	if (strict_kernel_rwx_enabled())
-		__map_without_ltlbs = 1;
-}
-
 /*
  * MMU_init sets up the basic memory mappings for the kernel,
  * including both RAM and possibly some I/O regions,
@@ -102,9 +82,6 @@ void __init MMU_init(void)
 	if (ppc_md.progress)
 		ppc_md.progress("MMU:enter", 0x111);
 
-	/* parse args from command line */
-	MMU_setup();
-
 	/*
 	 * Reserve gigantic pages for hugetlb.  This MUST occur before
 	 * lowmem_end_addr is initialized below.
diff --git a/arch/powerpc/mm/nohash/40x.c b/arch/powerpc/mm/nohash/40x.c
index b32e465a3d52..3684d6e570fb 100644
--- a/arch/powerpc/mm/nohash/40x.c
+++ b/arch/powerpc/mm/nohash/40x.c
@@ -43,7 +43,6 @@
 
 #include <mm/mmu_decl.h>
 
-extern int __map_without_ltlbs;
 /*
  * MMU_init_hw does the chip-specific initialization of the MMU hardware.
  */
@@ -94,7 +93,13 @@ unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
 	p = 0;
 	s = total_lowmem;
 
-	if (__map_without_ltlbs)
+	if (IS_ENABLED(CONFIG_KFENCE))
+		return 0;
+
+	if (debug_pagealloc_enabled())
+		return 0;
+
+	if (strict_kernel_rwx_enabled())
 		return 0;
 
 	while (s >= LARGE_PAGE_SIZE_16M) {
-- 
2.36.1