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Subject[PATCH] [PATCH] ARM64: Setup DMA32 zone size by bootargs
Date
Allowing the DMA32 zone be configurable in ARM64 but at most 4Gb.

Signed-off-by: Alix Wu <alix.wu@mediatek.com>
Signed-off-by: YJ Chiang <yj.chiang@mediatek.com>
Signed-off-by: Phil Chang <phil.chang@mediatek.com>
---

.../admin-guide/kernel-parameters.txt | 3 ++
arch/arm64/include/asm/memory.h | 2 +
arch/arm64/mm/init.c | 39 +++++++++++++++++--
3 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index bdc1f33fd3d1..5be6259e9ba8 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -980,6 +980,9 @@
The filter can be disabled or changed to another
driver later using sysfs.

+ dma32_size=nn[MG] [KNL,BOOT,ARM64]
+ Forces the DMA32 zone size of <nn> in MB.
+
driver_async_probe= [KNL]
List of driver names to be probed asynchronously.
Format: <driver_name1>,<driver_name2>...
diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h
index afa722504bfd..710de08ae8ae 100644
--- a/arch/arm64/include/asm/memory.h
+++ b/arch/arm64/include/asm/memory.h
@@ -175,6 +175,8 @@ extern u64 kimage_vaddr;
/* the offset between the kernel virtual and physical mappings */
extern u64 kimage_voffset;

+extern phys_addr_t dma32_zone_size;
+
static inline unsigned long kaslr_offset(void)
{
return kimage_vaddr - KIMAGE_VADDR;
diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
index 481d22c32a2e..c8af53680d46 100644
--- a/arch/arm64/mm/init.c
+++ b/arch/arm64/mm/init.c
@@ -60,6 +60,9 @@ EXPORT_SYMBOL(physvirt_offset);
struct page *vmemmap __ro_after_init;
EXPORT_SYMBOL(vmemmap);

+phys_addr_t dma32_zone_size __ro_after_init;
+EXPORT_SYMBOL(dma32_zone_size);
+
/*
* We create both ZONE_DMA and ZONE_DMA32. ZONE_DMA covers the first 1G of
* memory as some devices, namely the Raspberry Pi 4, have peripherals with
@@ -242,6 +245,29 @@ static int __init early_mem(char *p)
}
early_param("mem", early_mem);

+static int __init setup_dma32_zone(char *p)
+{
+ u64 size;
+
+ if (!p)
+ return -EINVAL;
+
+ if (kstrtoull(p, 0, &size))
+ return -EINVAL;
+
+ /* DMA32 zone size should never grater than 4G */
+ if (size > max_zone_phys(32) / SZ_1M)
+ return -EINVAL;
+
+ pr_notice("Setup dma32 zone size to %llu Mb\n", size);
+
+ dma32_zone_size = size * SZ_1M;
+
+ return 0;
+}
+
+early_param("dma32_size", setup_dma32_zone);
+
static int __init early_init_dt_scan_usablemem(unsigned long node,
const char *uname, int depth, void *data)
{
@@ -392,10 +418,17 @@ void __init arm64_memblock_init(void)
arm64_dma_phys_limit = max_zone_phys(ARM64_ZONE_DMA_BITS);
}

- if (IS_ENABLED(CONFIG_ZONE_DMA32))
- arm64_dma32_phys_limit = max_zone_phys(32);
- else
+ if (IS_ENABLED(CONFIG_ZONE_DMA32)) {
+ if (dma32_zone_size) {
+ arm64_dma32_phys_limit = min(max_zone_phys(32),
+ dma32_zone_size + memblock_start_of_DRAM());
+ } else {
+ arm64_dma32_phys_limit = max_zone_phys(32);
+ dma32_zone_size = arm64_dma32_phys_limit;
+ }
+ } else {
arm64_dma32_phys_limit = PHYS_MASK + 1;
+ }

reserve_crashkernel();

--
2.18.0
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