[PATCHv2,1/2] arm: Cleanup sanity_check_meminfo

Commit Message

Laura Abbott Jan. 5, 2017, 11:01 p.m. UTC

The logic for sanity_check_meminfo has become difficult to
follow. Clean up the code so it's more obvious what the code
is actually trying to do. Additionally, meminfo is now removed
so rename the function to better describe it's purpose.

Signed-off-by: Laura Abbott <[e-mail]>
Signed-off-by: Laura Abbott <[e-mail]>
---
v2: Fixed code so b9a019899f61 ("ARM: 8590/1: sanity_check_meminfo():
avoid overflow on vmalloc_limit") should stay fixed. The casting and assignment
still seem ugly. Also corrected the size for memblock_remove with
!CONFIG_HIGHMEM (found by inspection, memblock was handling it properly).
---
 arch/arm/kernel/setup.c |  4 +--
 arch/arm/mm/mmu.c       | 65 ++++++++++++++++++-------------------------------
 arch/arm/mm/nommu.c     |  8 +++---
 3 files changed, 30 insertions(+), 47 deletions(-)

Comments

Nicolas Pitre Jan. 6, 2017, 4:17 a.m. UTC | #1

On Thu, 5 Jan 2017, Laura Abbott wrote:

> 
> The logic for sanity_check_meminfo has become difficult to
> follow. Clean up the code so it's more obvious what the code
> is actually trying to do. Additionally, meminfo is now removed
> so rename the function to better describe it's purpose.

s/it's/its/

> Signed-off-by: Laura Abbott <[e-mail]>
> Signed-off-by: Laura Abbott <[e-mail]>
> ---
> v2: Fixed code so b9a019899f61 ("ARM: 8590/1: sanity_check_meminfo():
> avoid overflow on vmalloc_limit") should stay fixed. The casting and assignment
> still seem ugly.

Are you referring to the initial vmalloc_limit assignment?

> @@ -1172,43 +1170,19 @@ void __init sanity_check_meminfo(void)
>  	for_each_memblock(memory, reg) {
>  		phys_addr_t block_start = reg->base;
>  		phys_addr_t block_end = reg->base + reg->size;
> -		phys_addr_t size_limit = reg->size;
>  
> -		if (reg->base >= vmalloc_limit)
> -			highmem = 1;
> -		else
> -			size_limit = vmalloc_limit - reg->base;
>  
> -
[...]

This leaves a spurious empty line. One was already there before your 
patch but this would be a good opportunity to remove it.

Other than that...

Reviewed-by: Nicolas Pitre <[e-mail]>


Nicolas

Laura Abbott Jan. 10, 2017, 1:07 a.m. UTC | #2

On 01/05/2017 08:17 PM, Nicolas Pitre wrote:
> On Thu, 5 Jan 2017, Laura Abbott wrote:
> 
>>
>> The logic for sanity_check_meminfo has become difficult to
>> follow. Clean up the code so it's more obvious what the code
>> is actually trying to do. Additionally, meminfo is now removed
>> so rename the function to better describe it's purpose.
> 
> s/it's/its/
> 
>> Signed-off-by: Laura Abbott <[e-mail]>
>> Signed-off-by: Laura Abbott <[e-mail]>
>> ---
>> v2: Fixed code so b9a019899f61 ("ARM: 8590/1: sanity_check_meminfo():
>> avoid overflow on vmalloc_limit") should stay fixed. The casting and assignment
>> still seem ugly.
> 
> Are you referring to the initial vmalloc_limit assignment?
> 

I was referring to the min_t with u64 that gets assigned to phys_addr_t.
for lowmem_limit

>> @@ -1172,43 +1170,19 @@ void __init sanity_check_meminfo(void)
>>  	for_each_memblock(memory, reg) {
>>  		phys_addr_t block_start = reg->base;
>>  		phys_addr_t block_end = reg->base + reg->size;
>> -		phys_addr_t size_limit = reg->size;
>>  
>> -		if (reg->base >= vmalloc_limit)
>> -			highmem = 1;
>> -		else
>> -			size_limit = vmalloc_limit - reg->base;
>>  
>> -
> [...]
> 
> This leaves a spurious empty line. One was already there before your 
> patch but this would be a good opportunity to remove it.
> 
> Other than that...
> 
> Reviewed-by: Nicolas Pitre <[e-mail]>
> 
> 
> Nicolas
> 

Thanks,
Laura

Patch

diff --git a/arch/arm/kernel/setup.c b/arch/arm/kernel/setup.c
index 34e3f3c..8a8051c 100644
--- a/arch/arm/kernel/setup.c
+++ b/arch/arm/kernel/setup.c
@@ -81,7 +81,7 @@  __setup("fpe=", fpe_setup);
 extern void init_default_cache_policy(unsigned long);
 extern void paging_init(const struct machine_desc *desc);
 extern void early_paging_init(const struct machine_desc *);
-extern void sanity_check_meminfo(void);
+extern void adjust_lowmem_bounds(void);
 extern enum reboot_mode reboot_mode;
 extern void setup_dma_zone(const struct machine_desc *desc);
 
@@ -1093,7 +1093,7 @@  void __init setup_arch(char **cmdline_p)
 	setup_dma_zone(mdesc);
 	xen_early_init();
 	efi_init();
-	sanity_check_meminfo();
+	adjust_lowmem_bounds();
 	arm_memblock_init(mdesc);
 
 	early_ioremap_reset();
diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
index 4001dd1..ce5123b 100644
--- a/arch/arm/mm/mmu.c
+++ b/arch/arm/mm/mmu.c
@@ -1152,13 +1152,11 @@  early_param("vmalloc", early_vmalloc);
 
 phys_addr_t arm_lowmem_limit __initdata = 0;
 
-void __init sanity_check_meminfo(void)
+void __init adjust_lowmem_bounds(void)
 {
 	phys_addr_t memblock_limit = 0;
-	int highmem = 0;
 	u64 vmalloc_limit;
 	struct memblock_region *reg;
-	bool should_use_highmem = false;
 
 	/*
 	 * Let's use our own (unoptimized) equivalent of __pa() that is
@@ -1172,43 +1170,19 @@  void __init sanity_check_meminfo(void)
 	for_each_memblock(memory, reg) {
 		phys_addr_t block_start = reg->base;
 		phys_addr_t block_end = reg->base + reg->size;
-		phys_addr_t size_limit = reg->size;
 
-		if (reg->base >= vmalloc_limit)
-			highmem = 1;
-		else
-			size_limit = vmalloc_limit - reg->base;
 
-
-		if (!IS_ENABLED(CONFIG_HIGHMEM) || cache_is_vipt_aliasing()) {
-
-			if (highmem) {
-				pr_notice("Ignoring RAM at %pa-%pa (!CONFIG_HIGHMEM)\n",
-					  &block_start, &block_end);
-				memblock_remove(reg->base, reg->size);
-				should_use_highmem = true;
-				continue;
-			}
-
-			if (reg->size > size_limit) {
-				phys_addr_t overlap_size = reg->size - size_limit;
-
-				pr_notice("Truncating RAM at %pa-%pa",
-					  &block_start, &block_end);
-				block_end = vmalloc_limit;
-				pr_cont(" to -%pa", &block_end);
-				memblock_remove(vmalloc_limit, overlap_size);
-				should_use_highmem = true;
-			}
-		}
-
-		if (!highmem) {
-			if (block_end > arm_lowmem_limit) {
-				if (reg->size > size_limit)
-					arm_lowmem_limit = vmalloc_limit;
-				else
-					arm_lowmem_limit = block_end;
-			}
+		if (reg->base < vmalloc_limit) {
+			if (block_end > arm_lowmem_limit)
+				/*
+				 * Compare as u64 to ensure vmalloc_limit does
+				 * not get truncated. block_end should always
+				 * fit in phys_addr_t so there should be no
+				 * issue with assignment.
+				 */
+				arm_lowmem_limit = min_t(u64,
+							 vmalloc_limit,
+							 block_end);
 
 			/*
 			 * Find the first non-pmd-aligned page, and point
@@ -1233,9 +1207,6 @@  void __init sanity_check_meminfo(void)
 		}
 	}
 
-	if (should_use_highmem)
-		pr_notice("Consider using a HIGHMEM enabled kernel.\n");
-
 	high_memory = __va(arm_lowmem_limit - 1) + 1;
 
 	/*
@@ -1248,6 +1219,18 @@  void __init sanity_check_meminfo(void)
 	if (!memblock_limit)
 		memblock_limit = arm_lowmem_limit;
 
+	if (!IS_ENABLED(CONFIG_HIGHMEM) || cache_is_vipt_aliasing()) {
+		if (memblock_end_of_DRAM() > arm_lowmem_limit) {
+			phys_addr_t end = memblock_end_of_DRAM();
+
+			pr_notice("Ignoring RAM at %pa-%pa\n",
+				  &memblock_limit, &end);
+			pr_notice("Consider using a HIGHMEM enabled kernel.\n");
+
+			memblock_remove(memblock_limit, end - memblock_limit);
+		}
+	}
+
 	memblock_set_current_limit(memblock_limit);
 }
 
diff --git a/arch/arm/mm/nommu.c b/arch/arm/mm/nommu.c
index 2740967..13a25d6 100644
--- a/arch/arm/mm/nommu.c
+++ b/arch/arm/mm/nommu.c
@@ -85,7 +85,7 @@  static unsigned long irbar_read(void)
 }
 
 /* MPU initialisation functions */
-void __init sanity_check_meminfo_mpu(void)
+void __init adjust_lowmem_bounds_mpu(void)
 {
 	phys_addr_t phys_offset = PHYS_OFFSET;
 	phys_addr_t aligned_region_size, specified_mem_size, rounded_mem_size;
@@ -274,7 +274,7 @@  void __init mpu_setup(void)
 	}
 }
 #else
-static void sanity_check_meminfo_mpu(void) {}
+static void adjust_lowmem_bounds_mpu(void) {}
 static void __init mpu_setup(void) {}
 #endif /* CONFIG_ARM_MPU */
 
@@ -295,10 +295,10 @@  void __init arm_mm_memblock_reserve(void)
 #endif
 }
 
-void __init sanity_check_meminfo(void)
+void __init adjust_lowmem_bounds(void)
 {
 	phys_addr_t end;
-	sanity_check_meminfo_mpu();
+	adjust_lowmem_bounds_mpu();
 	end = memblock_end_of_DRAM();
 	high_memory = __va(end - 1) + 1;
 	memblock_set_current_limit(end);