From: ard.biesheuvel@linaro.org (Ard Biesheuvel)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 7/8] arm64/kernel: drop __PHYS_OFFSET register with file scope from head.S
Date: Mon, 4 Apr 2016 16:52:23 +0200 [thread overview]
Message-ID: <1459781544-14310-8-git-send-email-ard.biesheuvel@linaro.org> (raw)
In-Reply-To: <1459781544-14310-1-git-send-email-ard.biesheuvel@linaro.org>
Instead of keeping __PHYS_OFFSET in a callee saved register with file
scope in head.S, derive the value on demand. This makes for cleaner
and more maintainable code.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
---
arch/arm64/kernel/head.S | 26 +++++++++++---------
1 file changed, 14 insertions(+), 12 deletions(-)
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index d28fc345bec3..23d03da7ecfe 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -213,7 +213,6 @@ ENTRY(stext)
bl preserve_boot_args
bl el2_setup // Drop to EL1, w0=cpu_boot_mode
mov x23, xzr // KASLR offset, defaults to 0
- adrp x24, __PHYS_OFFSET
bl set_cpu_boot_mode_flag
bl __create_page_tables
/*
@@ -396,7 +395,7 @@ __create_page_tables:
create_pgd_entry x0, x5, x3, x6
ldr w6, kernel_img_size
add x6, x6, x5
- mov x3, x24 // phys offset
+ adrp x3, __PHYS_OFFSET
create_block_map x0, x7, x3, x5, x6
/*
@@ -417,7 +416,7 @@ kernel_img_size:
.ltorg
/*
- * The following fragment of code is executed with the MMU enabled.
+ * __mmap_switched(u64 phys_offset) - virtual entry point for the boot CPU
*/
__mmap_switched:
adrp x4, init_thread_union
@@ -431,14 +430,6 @@ __mmap_switched:
msr vbar_el1, x8 // vector table address
isb
- // Clear BSS
- adr_l x0, __bss_start
- mov x1, xzr
- adr_l x2, __bss_stop
- sub x2, x2, x0
- bl __pi_memset
- dsb ishst // Make zero page visible to PTW
-
#ifdef CONFIG_RELOCATABLE
/*
@@ -479,8 +470,17 @@ __mmap_switched:
#endif
ldr_l x4, kimage_vaddr // Save the offset between
- sub x4, x4, x24 // the kernel virtual and
+ sub x4, x4, x0 // the kernel virtual and
str_l x4, kimage_voffset, x5 // physical mappings
+
+ // Clear BSS
+ adr_l x0, __bss_start
+ mov x1, xzr
+ adr_l x2, __bss_stop
+ sub x2, x2, x0
+ bl __pi_memset
+ dsb ishst // Make zero page visible to PTW
+
#ifdef CONFIG_KASAN
bl kasan_early_init
#endif
@@ -774,6 +774,7 @@ __enable_mmu:
mov x20, x1 // preserve branch target
#ifdef CONFIG_RANDOMIZE_BASE
mov x19, x0 // preserve new SCTLR_EL1 value
+ adrp x0, __PHYS_OFFSET
blr x1
/*
@@ -792,6 +793,7 @@ __enable_mmu:
isb
add x20, x20, x23 // relocated __mmap_switched
#endif
+ adrp x0, __PHYS_OFFSET
br x20
ENDPROC(__enable_mmu)
--
2.5.0
next prev parent reply other threads:[~2016-04-04 14:52 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-04 14:52 [PATCH 0/8] arm64: 2016 head.S spring cleaning Ard Biesheuvel
2016-04-04 14:52 ` [PATCH 1/8] arm64/kernel: use literal for relocated address of __secondary_switched Ard Biesheuvel
2016-04-07 9:38 ` Will Deacon
2016-04-07 9:43 ` Ard Biesheuvel
2016-04-04 14:52 ` [PATCH 2/8] arm64/kernel: reuse boot_args array to get to __fdt_pointer Ard Biesheuvel
2016-04-04 15:13 ` James Morse
2016-04-04 15:19 ` Ard Biesheuvel
2016-04-05 11:09 ` Ard Biesheuvel
2016-04-04 14:52 ` [PATCH 3/8] arm64/kernel: use a proper stack frame in __mmap_switched() Ard Biesheuvel
2016-04-04 15:33 ` James Morse
2016-04-04 15:40 ` Ard Biesheuvel
2016-04-04 14:52 ` [PATCH 4/8] arm64/kernel: use ordinary calling convention for EL2 setup Ard Biesheuvel
2016-04-04 14:52 ` [PATCH 5/8] arm64/kernel: refer to idmap_pg_dir and swapper_pg_dir directly Ard Biesheuvel
2016-04-04 14:52 ` [PATCH 6/8] arm64/kernel: pass virtual entry point as __enable_mmu() argument Ard Biesheuvel
2016-04-04 14:52 ` Ard Biesheuvel [this message]
2016-04-04 14:52 ` [PATCH 8/8] arm64/kernel: drop global kaslr_offset in x23 from head.S Ard Biesheuvel
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