This patchset implements two-stagged initial page table setup using fixmap
to avoid mapping non-existent RAM and also reduce high_memory consumed by
initial page tables.
The patchset is based on Linux-5.2-rc3 and tested on SiFive Unleashed board
and QEMU virt machine.
These patches can be found in riscv_setup_vm_v5 branch of
https//github.com/avpatel/linux.git
Changes since v4:
- Added dtb_early_va which points to DTB for early parsing
Changes since v3:
- Changed patch series subject.
- Dropped PATCH1 because it's already merged
- Dropped PATCH3 because trampoline page table handles a corner case
for 32bit systems where load address range overlaps kernel virtual
address range
- Revamped PATCH for 4K aligned booting into two-stagged initial page
table setup
Changes since v2:
- Dropped PATCH2 because we have separate fix for Linux-5.1-rcX
- Moved PATCH5 to PATCH2
- Moved PATCH4 to PATCH3
- The "Booting kernel from any 4KB aligned address" is now PATCH4
Changes since v1:
- Add kconfig option BOOT_PAGE_ALIGNED to enable 4KB aligned booting
- Improved initial page table setup code to select best/biggest
possible mapping size based on load address alignment
- Added PATCH4 to remove redundant trampoline page table
- Added PATCH5 to fix memory reservation in setup_bootmem()
Anup Patel (2):
RISC-V: Fix memory reservation in setup_bootmem()
RISC-V: Setup initial page tables in two stages
arch/riscv/include/asm/fixmap.h | 5 +
arch/riscv/include/asm/pgtable-64.h | 5 +
arch/riscv/include/asm/pgtable.h | 8 +
arch/riscv/kernel/head.S | 17 +-
arch/riscv/kernel/setup.c | 6 +-
arch/riscv/mm/init.c | 331 ++++++++++++++++++++++------
6 files changed, 292 insertions(+), 80 deletions(-)
--
2.17.1
Currently, the setup_bootmem() reserves memory from RAM start to the
kernel end. This prevents us from exploring ways to use the RAM below
(or before) the kernel start hence this patch updates setup_bootmem()
to only reserve memory from the kernel start to the kernel end.
Suggested-by: Mike Rapoport <[email protected]>
Signed-off-by: Anup Patel <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
---
arch/riscv/mm/init.c | 14 +++++++-------
1 file changed, 7 insertions(+), 7 deletions(-)
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index 8bf6f9c2d48c..1879501bd156 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -29,6 +29,8 @@ unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
__page_aligned_bss;
EXPORT_SYMBOL(empty_zero_page);
+extern char _start[];
+
static void __init zone_sizes_init(void)
{
unsigned long max_zone_pfns[MAX_NR_ZONES] = { 0, };
@@ -103,18 +105,14 @@ void __init setup_bootmem(void)
{
struct memblock_region *reg;
phys_addr_t mem_size = 0;
+ phys_addr_t vmlinux_end = __pa(&_end);
+ phys_addr_t vmlinux_start = __pa(&_start);
/* Find the memory region containing the kernel */
for_each_memblock(memory, reg) {
- phys_addr_t vmlinux_end = __pa(_end);
phys_addr_t end = reg->base + reg->size;
if (reg->base <= vmlinux_end && vmlinux_end <= end) {
- /*
- * Reserve from the start of the region to the end of
- * the kernel
- */
- memblock_reserve(reg->base, vmlinux_end - reg->base);
mem_size = min(reg->size, (phys_addr_t)-PAGE_OFFSET);
/*
@@ -128,6 +126,9 @@ void __init setup_bootmem(void)
}
BUG_ON(mem_size == 0);
+ /* Reserve from the start of the kernel to the end of the kernel */
+ memblock_reserve(vmlinux_start, vmlinux_end - vmlinux_start);
+
set_max_mapnr(PFN_DOWN(mem_size));
max_low_pfn = PFN_DOWN(memblock_end_of_DRAM());
@@ -205,7 +206,6 @@ void __set_fixmap(enum fixed_addresses idx, phys_addr_t phys, pgprot_t prot)
asmlinkage void __init setup_vm(void)
{
- extern char _start;
uintptr_t i;
uintptr_t pa = (uintptr_t) &_start;
pgprot_t prot = __pgprot(pgprot_val(PAGE_KERNEL) | _PAGE_EXEC);
--
2.17.1
On Fri, Jun 7, 2019 at 11:31 AM Anup Patel <[email protected]> wrote:
>
> This patchset implements two-stagged initial page table setup using fixmap
> to avoid mapping non-existent RAM and also reduce high_memory consumed by
> initial page tables.
>
> The patchset is based on Linux-5.2-rc3 and tested on SiFive Unleashed board
> and QEMU virt machine.
>
> These patches can be found in riscv_setup_vm_v5 branch of
> https//github.com/avpatel/linux.git
>
> Changes since v4:
> - Added dtb_early_va which points to DTB for early parsing
>
> Changes since v3:
> - Changed patch series subject.
> - Dropped PATCH1 because it's already merged
> - Dropped PATCH3 because trampoline page table handles a corner case
> for 32bit systems where load address range overlaps kernel virtual
> address range
> - Revamped PATCH for 4K aligned booting into two-stagged initial page
> table setup
>
> Changes since v2:
> - Dropped PATCH2 because we have separate fix for Linux-5.1-rcX
> - Moved PATCH5 to PATCH2
> - Moved PATCH4 to PATCH3
> - The "Booting kernel from any 4KB aligned address" is now PATCH4
>
> Changes since v1:
> - Add kconfig option BOOT_PAGE_ALIGNED to enable 4KB aligned booting
> - Improved initial page table setup code to select best/biggest
> possible mapping size based on load address alignment
> - Added PATCH4 to remove redundant trampoline page table
> - Added PATCH5 to fix memory reservation in setup_bootmem()
>
> Anup Patel (2):
> RISC-V: Fix memory reservation in setup_bootmem()
> RISC-V: Setup initial page tables in two stages
>
> arch/riscv/include/asm/fixmap.h | 5 +
> arch/riscv/include/asm/pgtable-64.h | 5 +
> arch/riscv/include/asm/pgtable.h | 8 +
> arch/riscv/kernel/head.S | 17 +-
> arch/riscv/kernel/setup.c | 6 +-
> arch/riscv/mm/init.c | 331 ++++++++++++++++++++++------
> 6 files changed, 292 insertions(+), 80 deletions(-)
>
> --
> 2.17.1
Hi All,
Any comments on this series?
Regards,
Anup
On Fri, 7 Jun 2019, Anup Patel wrote:
> Currently, the setup_bootmem() reserves memory from RAM start to the
> kernel end. This prevents us from exploring ways to use the RAM below
> (or before) the kernel start hence this patch updates setup_bootmem()
> to only reserve memory from the kernel start to the kernel end.
>
> Suggested-by: Mike Rapoport <[email protected]>
> Signed-off-by: Anup Patel <[email protected]>
> Reviewed-by: Christoph Hellwig <[email protected]>
Thanks, queued for v5.3.
- Paul