[PATCH 1/3] powerpc/32: Remove the 'nobats' kernel parameter

[PATCH 1/3] powerpc/32: Remove the 'nobats' kernel parameter

[Christophe Leroy]

Mapping without BATs doesn't bring any added value to the user.

Remove that option.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
---
 Documentation/admin-guide/kernel-parameters.txt |  3 ---
 arch/powerpc/mm/book3s32/mmu.c                  |  2 +-
 arch/powerpc/mm/init_32.c                       | 11 -----------
 arch/powerpc/mm/mmu_decl.h                      |  1 -
 arch/powerpc/platforms/83xx/misc.c              | 14 ++++++--------
 5 files changed, 7 insertions(+), 24 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 8090130b544b..96de3f1ece00 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3495,9 +3495,6 @@
 
 	noautogroup	Disable scheduler automatic task group creation.
 
-	nobats		[PPC] Do not use BATs for mapping kernel lowmem
-			on "Classic" PPC cores.
-
 	nocache		[ARM]
 
 	nodsp		[SH] Disable hardware DSP at boot time.
diff --git a/arch/powerpc/mm/book3s32/mmu.c b/arch/powerpc/mm/book3s32/mmu.c
index 49a737fbbd18..1794132db31e 100644
--- a/arch/powerpc/mm/book3s32/mmu.c
+++ b/arch/powerpc/mm/book3s32/mmu.c
@@ -161,7 +161,7 @@ unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
 	unsigned long border = (unsigned long)__init_begin - PAGE_OFFSET;
 
 
-	if (debug_pagealloc_enabled_or_kfence() || __map_without_bats) {
+	if (debug_pagealloc_enabled_or_kfence()) {
 		pr_debug_once("Read-Write memory mapped without BATs\n");
 		if (base >= border)
 			return base;
diff --git a/arch/powerpc/mm/init_32.c b/arch/powerpc/mm/init_32.c
index 693a3a7a9463..321794747ea1 100644
--- a/arch/powerpc/mm/init_32.c
+++ b/arch/powerpc/mm/init_32.c
@@ -69,12 +69,6 @@ EXPORT_SYMBOL(agp_special_page);
 
 void MMU_init(void);
 
-/*
- * this tells the system to map all of ram with the segregs
- * (i.e. page tables) instead of the bats.
- * -- Cort
- */
-int __map_without_bats;
 int __map_without_ltlbs;
 
 /* max amount of low RAM to map in */
@@ -85,11 +79,6 @@ unsigned long __max_low_memory = MAX_LOW_MEM;
  */
 static void __init MMU_setup(void)
 {
-	/* Check for nobats option (used in mapin_ram). */
-	if (strstr(boot_command_line, "nobats")) {
-		__map_without_bats = 1;
-	}
-
 	if (strstr(boot_command_line, "noltlbs")) {
 		__map_without_ltlbs = 1;
 	}
diff --git a/arch/powerpc/mm/mmu_decl.h b/arch/powerpc/mm/mmu_decl.h
index 63c4b1a4d435..229c72e49198 100644
--- a/arch/powerpc/mm/mmu_decl.h
+++ b/arch/powerpc/mm/mmu_decl.h
@@ -92,7 +92,6 @@ extern void mapin_ram(void);
 extern void setbat(int index, unsigned long virt, phys_addr_t phys,
 		   unsigned int size, pgprot_t prot);
 
-extern int __map_without_bats;
 extern unsigned int rtas_data, rtas_size;
 
 struct hash_pte;
diff --git a/arch/powerpc/platforms/83xx/misc.c b/arch/powerpc/platforms/83xx/misc.c
index 3285dabcf923..2fb2a85d131f 100644
--- a/arch/powerpc/platforms/83xx/misc.c
+++ b/arch/powerpc/platforms/83xx/misc.c
@@ -121,17 +121,15 @@ void __init mpc83xx_setup_pci(void)
 
 void __init mpc83xx_setup_arch(void)
 {
+	phys_addr_t immrbase = get_immrbase();
+	int immrsize = IS_ALIGNED(immrbase, SZ_2M) ? SZ_2M : SZ_1M;
+	unsigned long va = fix_to_virt(FIX_IMMR_BASE);
+
 	if (ppc_md.progress)
 		ppc_md.progress("mpc83xx_setup_arch()", 0);
 
-	if (!__map_without_bats) {
-		phys_addr_t immrbase = get_immrbase();
-		int immrsize = IS_ALIGNED(immrbase, SZ_2M) ? SZ_2M : SZ_1M;
-		unsigned long va = fix_to_virt(FIX_IMMR_BASE);
-
-		setbat(-1, va, immrbase, immrsize, PAGE_KERNEL_NCG);
-		update_bats();
-	}
+	setbat(-1, va, immrbase, immrsize, PAGE_KERNEL_NCG);
+	update_bats();
 }
 
 int machine_check_83xx(struct pt_regs *regs)
-- 
2.36.1

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

[Christophe Leroy]

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@csgroup.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

[PATCH 3/3] powerpc/32: Remove __map_without_ltlbs

[Christophe Leroy]

__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@csgroup.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

Re: [PATCH 1/3] powerpc/32: Remove the 'nobats' kernel parameter

[Michael Ellerman]

On Tue, 14 Jun 2022 12:32:23 +0200, Christophe Leroy wrote:
> Mapping without BATs doesn't bring any added value to the user.
> 
> Remove that option.
> 
> 

Applied to powerpc/next.

[1/3] powerpc/32: Remove the 'nobats' kernel parameter
      https://git.kernel.org/powerpc/c/1ce844973bb516e95d3f2bcb001a3992548def9d
[2/3] powerpc/32: Remove 'noltlbs' kernel parameter
      https://git.kernel.org/powerpc/c/56e54b4e6c477b2a7df43f9a320ae5f9a5bfb16c
[3/3] powerpc/32: Remove __map_without_ltlbs
      https://git.kernel.org/powerpc/c/513f5bbac7b9ca7046bc350dd6eb39b957e338a7

cheers