linux-kernel - [PATCH 2/3] powerpc/32: Remove 'noltlbs' kernel parameter

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Message-Id: <80ca17bd39cf608a8ebd0764d7064a498e131199.1655202721.git.christophe.leroy@csgroup.eu>
Date:   Tue, 14 Jun 2022 12:32:24 +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 2/3] powerpc/32: Remove 'noltlbs' kernel parameter

Mapping without large TLBs has no added value on the 8xx.

Mapping without large TLBs is still necessary on 40x when
selecting CONFIG_KFENCE or CONFIG_DEBUG_PAGEALLOC or
CONFIG_STRICT_KERNEL_RWX, but this is done automatically
and doesn't require user selection.

Remove 'noltlbs' kernel parameter, the user has no reason
to use it.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 Documentation/admin-guide/kernel-parameters.txt | 3 ---
 arch/powerpc/mm/init_32.c                       | 3 ---
 arch/powerpc/mm/nohash/8xx.c                    | 9 ---------
 3 files changed, 15 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 96de3f1ece00..2322e429150d 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3661,9 +3661,6 @@
 
 	nolapic_timer	[X86-32,APIC] Do not use the local APIC timer.
 
-	noltlbs		[PPC] Do not use large page/tlb entries for kernel
-			lowmem mapping on PPC40x and PPC8xx
-
 	nomca		[IA-64] Disable machine check abort handling
 
 	nomce		[X86-32] Disable Machine Check Exception
diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
index 321794747ea1..6f2e6210c273 100644
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -79,9 +79,6 @@ unsigned long __max_low_memory = MAX_LOW_MEM;
  */
 static void __init MMU_setup(void)
 {
-	if (strstr(boot_command_line, "noltlbs")) {
-		__map_without_ltlbs = 1;
-	}
 	if (IS_ENABLED(CONFIG_PPC_8xx))
 		return;
 
diff --git a/arch/powerpc/mm/nohash/8xx.c b/arch/powerpc/mm/nohash/8xx.c
index 27f9186ae374..6b668ccef836 100644
--- a/arch/powerpc/mm/nohash/8xx.c
+++ b/arch/powerpc/mm/nohash/8xx.c
@@ -14,8 +14,6 @@
 
 #define IMMR_SIZE (FIX_IMMR_SIZE << PAGE_SHIFT)
 
-extern int __map_without_ltlbs;
-
 static unsigned long block_mapped_ram;
 
 /*
@@ -28,8 +26,6 @@ phys_addr_t v_block_mapped(unsigned long va)
 
 	if (va >= VIRT_IMMR_BASE && va < VIRT_IMMR_BASE + IMMR_SIZE)
 		return p + va - VIRT_IMMR_BASE;
-	if (__map_without_ltlbs)
-		return 0;
 	if (va >= PAGE_OFFSET && va < PAGE_OFFSET + block_mapped_ram)
 		return __pa(va);
 	return 0;
@@ -45,8 +41,6 @@ unsigned long p_block_mapped(phys_addr_t pa)
 
 	if (pa >= p && pa < p + IMMR_SIZE)
 		return VIRT_IMMR_BASE + pa - p;
-	if (__map_without_ltlbs)
-		return 0;
 	if (pa < block_mapped_ram)
 		return (unsigned long)__va(pa);
 	return 0;
@@ -153,9 +147,6 @@ unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
 
 	mmu_mapin_immr();
 
-	if (__map_without_ltlbs)
-		return 0;
-
 	mmu_mapin_ram_chunk(0, boundary, PAGE_KERNEL_TEXT, true);
 	if (debug_pagealloc_enabled_or_kfence()) {
 		top = boundary;
-- 
2.36.1