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RISC-V: Move relocate and few other functions out of __init

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The secondary hart booting and relocation code are under .init section.
As a result, it will be freed once kernel booting is done. However,
ordered booting protocol and CPU hotplug always requires these functions
to be present to bringup harts after initial kernel boot.

Move the required functions to a different section and make sure that
they are in memory within first 2MB offset as trampoline page directory
only maps first 2MB.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
This commit is contained in:
Atish Patra 2020-03-17 18:11:39 -07:00 committed by Palmer Dabbelt
parent 1ef46c231d
commit e011995e82
No known key found for this signature in database
GPG Key ID: 2E1319F35FBB1889
2 changed files with 86 additions and 72 deletions
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153
arch/riscv/kernel/head.S
View File

@ -14,7 +14,7 @@
#include <asm/hwcap.h>
#include <asm/image.h>
__INIT
__HEAD
ENTRY(_start)
/*
* Image header expected by Linux boot-loaders. The image header data
@ -45,8 +45,85 @@ ENTRY(_start)
.ascii RISCV_IMAGE_MAGIC2
.word 0
.global _start_kernel
_start_kernel:
.align 2
#ifdef CONFIG_MMU
relocate:
/* Relocate return address */
li a1, PAGE_OFFSET
la a2, _start
sub a1, a1, a2
add ra, ra, a1
/* Point stvec to virtual address of intruction after satp write */
la a2, 1f
add a2, a2, a1
csrw CSR_TVEC, a2
/* Compute satp for kernel page tables, but don't load it yet */
srl a2, a0, PAGE_SHIFT
li a1, SATP_MODE
or a2, a2, a1
/*
* Load trampoline page directory, which will cause us to trap to
* stvec if VA != PA, or simply fall through if VA == PA. We need a
* full fence here because setup_vm() just wrote these PTEs and we need
* to ensure the new translations are in use.
*/
la a0, trampoline_pg_dir
srl a0, a0, PAGE_SHIFT
or a0, a0, a1
sfence.vma
csrw CSR_SATP, a0
.align 2
1:
/* Set trap vector to spin forever to help debug */
la a0, .Lsecondary_park
csrw CSR_TVEC, a0
/* Reload the global pointer */
.option push
.option norelax
la gp, __global_pointer$
.option pop
/*
* Switch to kernel page tables. A full fence is necessary in order to
* avoid using the trampoline translations, which are only correct for
* the first superpage. Fetching the fence is guarnteed to work
* because that first superpage is translated the same way.
*/
csrw CSR_SATP, a2
sfence.vma
ret
#endif /* CONFIG_MMU */
#ifdef CONFIG_SMP
/* Set trap vector to spin forever to help debug */
la a3, .Lsecondary_park
csrw CSR_TVEC, a3
slli a3, a0, LGREG
.global secondary_start_common
secondary_start_common:
#ifdef CONFIG_MMU
/* Enable virtual memory and relocate to virtual address */
la a0, swapper_pg_dir
call relocate
#endif
tail smp_callin
#endif /* CONFIG_SMP */
.Lsecondary_park:
/* We lack SMP support or have too many harts, so park this hart */
wfi
j .Lsecondary_park
END(_start)
__INIT
ENTRY(_start_kernel)
/* Mask all interrupts */
csrw CSR_IE, zero
csrw CSR_IP, zero
@ -134,59 +211,6 @@ clear_bss_done:
call parse_dtb
tail start_kernel
#ifdef CONFIG_MMU
relocate:
/* Relocate return address */
li a1, PAGE_OFFSET
la a2, _start
sub a1, a1, a2
add ra, ra, a1
/* Point stvec to virtual address of intruction after satp write */
la a2, 1f
add a2, a2, a1
csrw CSR_TVEC, a2
/* Compute satp for kernel page tables, but don't load it yet */
srl a2, a0, PAGE_SHIFT
li a1, SATP_MODE
or a2, a2, a1
/*
* Load trampoline page directory, which will cause us to trap to
* stvec if VA != PA, or simply fall through if VA == PA. We need a
* full fence here because setup_vm() just wrote these PTEs and we need
* to ensure the new translations are in use.
*/
la a0, trampoline_pg_dir
srl a0, a0, PAGE_SHIFT
or a0, a0, a1
sfence.vma
csrw CSR_SATP, a0
.align 2
1:
/* Set trap vector to spin forever to help debug */
la a0, .Lsecondary_park
csrw CSR_TVEC, a0
/* Reload the global pointer */
.option push
.option norelax
la gp, __global_pointer$
.option pop
/*
* Switch to kernel page tables. A full fence is necessary in order to
* avoid using the trampoline translations, which are only correct for
* the first superpage. Fetching the fence is guarnteed to work
* because that first superpage is translated the same way.
*/
csrw CSR_SATP, a2
sfence.vma
ret
#endif /* CONFIG_MMU */
.Lsecondary_start:
#ifdef CONFIG_SMP
/* Set trap vector to spin forever to help debug */
@ -211,16 +235,10 @@ relocate:
beqz tp, .Lwait_for_cpu_up
fence
#ifdef CONFIG_MMU
/* Enable virtual memory and relocate to virtual address */
la a0, swapper_pg_dir
call relocate
tail secondary_start_common
#endif
tail smp_callin
#endif
END(_start)
END(_start_kernel)
#ifdef CONFIG_RISCV_M_MODE
ENTRY(reset_regs)
@ -301,13 +319,6 @@ ENTRY(reset_regs)
END(reset_regs)
#endif /* CONFIG_RISCV_M_MODE */
.section ".text", "ax",@progbits
.align 2
.Lsecondary_park:
/* We lack SMP support or have too many harts, so park this hart */
wfi
j .Lsecondary_park
__PAGE_ALIGNED_BSS
/* Empty zero page */
.balign PAGE_SIZE

5
arch/riscv/kernel/vmlinux.lds.S
View File

@ -11,6 +11,7 @@
#include <asm/thread_info.h>
#include <asm/set_memory.h>
#include <linux/sizes.h>
OUTPUT_ARCH(riscv)
ENTRY(_start)
@ -21,8 +22,10 @@ SECTIONS
/* Beginning of code and text segment */
. = LOAD_OFFSET;
_start = .;
__init_begin = .;
HEAD_TEXT_SECTION
. = ALIGN(PAGE_SIZE);
__init_begin = .;
INIT_TEXT_SECTION(PAGE_SIZE)
INIT_DATA_SECTION(16)
/* we have to discard exit text and such at runtime, not link time */