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authorLinus Walleij <linus.walleij@linaro.org>2021-06-03 09:51:21 +0100
committerRussell King (Oracle) <rmk+kernel@armlinux.org.uk>2021-06-13 18:16:41 +0100
commita91da54570856e3d3af4ba2884db71fbce06f70b (patch)
tree6a7cfbf300f11676e139292794744a472cef7e1b
parentb78f63f4439bbfd02bfc628114ed0f63460e5570 (diff)
ARM: 9089/1: Define kernel physical section start and end
When we are mapping the initial sections in head.S we know very well where the start and end of the kernel image in physical memory is placed. Later on it gets hard to determine this. Save the information into two variables named kernel_sec_start and kernel_sec_end for convenience for later work involving the physical start and end of the kernel. These variables are section-aligned corresponding to the early section mappings set up in head.S. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
-rw-r--r--arch/arm/include/asm/memory.h7
-rw-r--r--arch/arm/kernel/head.S27
2 files changed, 31 insertions, 3 deletions
diff --git a/arch/arm/include/asm/memory.h b/arch/arm/include/asm/memory.h
index a5f1d1826a98..ca213d7d095f 100644
--- a/arch/arm/include/asm/memory.h
+++ b/arch/arm/include/asm/memory.h
@@ -159,6 +159,13 @@ extern unsigned long vectors_base;
#ifndef __ASSEMBLY__
/*
+ * Physical start and end address of the kernel sections. These addresses are
+ * 2MB-aligned to match the section mappings placed over the kernel.
+ */
+extern phys_addr_t kernel_sec_start;
+extern phys_addr_t kernel_sec_end;
+
+/*
* Physical vs virtual RAM address space conversion. These are
* private definitions which should NOT be used outside memory.h
* files. Use virt_to_phys/phys_to_virt/__pa/__va instead.
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index 4e2daaa7636a..9eb0b4dbcc12 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -47,6 +47,20 @@
.globl swapper_pg_dir
.equ swapper_pg_dir, KERNEL_RAM_VADDR - PG_DIR_SIZE
+ /*
+ * This needs to be assigned at runtime when the linker symbols are
+ * resolved.
+ */
+ .pushsection .data
+ .align 2
+ .globl kernel_sec_start
+ .globl kernel_sec_end
+kernel_sec_start:
+ .long 0
+kernel_sec_end:
+ .long 0
+ .popsection
+
.macro pgtbl, rd, phys
add \rd, \phys, #TEXT_OFFSET
sub \rd, \rd, #PG_DIR_SIZE
@@ -229,16 +243,23 @@ __create_page_tables:
blo 1b
/*
- * Map our RAM from the start to the end of the kernel .bss section.
+ * The main matter: map in the kernel using section mappings, and
+ * set two variables to indicate the physical start and end of the
+ * kernel.
*/
- add r0, r4, #PAGE_OFFSET >> (SECTION_SHIFT - PMD_ORDER)
+ add r0, r4, #KERNEL_OFFSET >> (SECTION_SHIFT - PMD_ORDER)
ldr r6, =(_end - 1)
- orr r3, r8, r7
+ adr_l r5, kernel_sec_start @ _pa(kernel_sec_start)
+ str r8, [r5] @ Save physical start of kernel
+ orr r3, r8, r7 @ Add the MMU flags
add r6, r4, r6, lsr #(SECTION_SHIFT - PMD_ORDER)
1: str r3, [r0], #1 << PMD_ORDER
add r3, r3, #1 << SECTION_SHIFT
cmp r0, r6
bls 1b
+ eor r3, r3, r7 @ Remove the MMU flags
+ adr_l r5, kernel_sec_end @ _pa(kernel_sec_end)
+ str r3, [r5] @ Save physical end of kernel
#ifdef CONFIG_XIP_KERNEL
/*