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Message-Id: <1618230494-6207-6-git-send-email-hejinyang@loongson.cn>
Date: Mon, 12 Apr 2021 20:28:14 +0800
From: Jinyang He <hejinyang@...ngson.cn>
To: Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
Paul Burton <paulburton@...nel.org>
Cc: linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 5/5] MIPS: relocate: Add support to auto relocate kernel
These codes are base on arch/mips/kernel/kaslr.c. Once do_relocate_kernel
occurs, the kernel can hardly work normally, unless do_relocate_kernel
success. Follows are what boot cpu does in do_relocate_kernel.
1, Save args
2, Whether the PC meets expectation
Determine whether the kernel needs to be relocated. At this time, a0
is the difference between the PC and the fixed address in the kernel.
3, Whether offset 64KB aligned
4, Whether current _text and _end are in the PC region
Makesure RELOCATED(_text/_end) in same PC region, otherwise fail.
Because we used lots of j/jal in kernel.
5, get current __start/stop___ex_table address
Get RELOCATED(__start/stop___ex_table) first, and relocate them.
6, get current _relocation_start address
Get RELOCATED(_relocation_start address) and do relocation by info in
relocation table. 964 is based on apply_r_mips_64_rel, 932 is based on
apply_r_mips_32_rel, 926 is based on apply_r_mips_26_rel and 916 is
based on apply_r_mips_hi16_rel.
R_MIPS_26: 0~25bit: ((insn & 0x03ffffff) << 2 + offset) >> 2
= (insn & 0x03ffffff) + offset >> 2
R_MIPS_HI16: 0~15bit: ((insn & 0x0000ffff) << 16 + offset) >> 16
= (insn & 0x0000ffff) + offset >> 16
7, Complete! And flush i-cache
8, Restore args
All relocate process did 3 things in short, relocate ex_table, relocate
insructions and flush i-cache.
Signed-off-by: Jinyang He <hejinyang@...ngson.cn>
---
arch/mips/cavium-octeon/smp.c | 5 +-
.../asm/mach-cavium-octeon/kernel-entry-init.h | 13 ++
arch/mips/kernel/head.S | 158 +++++++++++++++++++++
3 files changed, 175 insertions(+), 1 deletion(-)
diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c
index dfdbc79..4201f08 100644
--- a/arch/mips/cavium-octeon/smp.c
+++ b/arch/mips/cavium-octeon/smp.c
@@ -28,9 +28,13 @@
volatile unsigned long octeon_processor_boot = 0xff;
volatile unsigned long octeon_processor_sp;
volatile unsigned long octeon_processor_gp;
+
+#ifdef CONFIG_RELOCATABLE
+volatile unsigned long relocate_finished = 1;
#ifdef CONFIG_RANDOMIZE_BASE
volatile unsigned long octeon_processor_relocated_kernel_entry;
#endif /* CONFIG_RANDOMIZE_BASE */
+#endif /* CONFIG_RELOCATABLE */
#ifdef CONFIG_HOTPLUG_CPU
uint64_t octeon_bootloader_entry_addr;
@@ -189,7 +193,6 @@ static void __init octeon_smp_setup(void)
octeon_smp_hotplug_setup();
}
-
#ifdef CONFIG_RANDOMIZE_BASE
int plat_post_relocation(long offset)
{
diff --git a/arch/mips/include/asm/mach-cavium-octeon/kernel-entry-init.h b/arch/mips/include/asm/mach-cavium-octeon/kernel-entry-init.h
index 21b9854..14acc3a 100644
--- a/arch/mips/include/asm/mach-cavium-octeon/kernel-entry-init.h
+++ b/arch/mips/include/asm/mach-cavium-octeon/kernel-entry-init.h
@@ -101,6 +101,19 @@
#ifdef CONFIG_SMP
+#ifdef CONFIG_RELOCATABLE
+ # Wait main processor finished relocation
+ bal 1f
+1: move t0, ra
+ PTR_LA t1, 1b
+ PTR_SUBU t0, t1
+ PTR_LA t1, relocate_finished
+ PTR_ADDU t0, t1
+2: nop
+ LONG_L t1, 0(t0)
+ bnez t1, 2b
+#endif /* CONFIG_RELOCATABLE */
+
#
# All cores other than the master need to wait here for SMP bootstrap
# to begin
diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S
index 6cfe23e..c431d27 100644
--- a/arch/mips/kernel/head.S
+++ b/arch/mips/kernel/head.S
@@ -81,6 +81,160 @@ FEXPORT(__kernel_entry)
#define PC_REGION_SHIFT 28
#define PC_REGION_MASK (~(1 << PC_REGION_SHIFT - 1))
+#define R_MIPS_32 2
+#define R_MIPS_26 4
+#define R_MIPS_HI16 5
+#define R_MIPS_64 18
+
+ .macro do_relocate_kernel
+ .set push
+ /* Save args */
+ move s0, a0
+ move s1, a1
+ move s2, a2
+ move s3, a3
+
+ /* Whether the PC meets expectation */
+ bal 1f
+1: move a0, ra
+ PTR_LA a1, 1b
+ PTR_SUB a0, a0, a1
+ beqz a0, 999f
+
+ /* Whether offset 64KB aligned */
+ and t0, a0, 0xffff
+ bnez t0, 999f
+
+ /* Whether current _text and _end are in the PC region */
+ PTR_LA t0, _end
+ PTR_ADDU t1, t0, a0
+ PTR_SRL t1, PC_REGION_SHIFT
+ PTR_SRL t0, PC_REGION_SHIFT
+ bne t0, t1, 999f
+
+ PTR_LA t0, _text
+ PTR_ADDU t1, t0, a0
+ move a3, t1
+ PTR_SRL t1, PC_REGION_SHIFT
+ PTR_SRL t0, PC_REGION_SHIFT
+ bne t0, t1, 999f
+
+ /* get current __start/stop___ex_table address */
+ PTR_LA a1, __start___ex_table
+ PTR_ADDU a1, a0
+ PTR_LA a2, __stop___ex_table
+ PTR_ADDU a2, a0
+
+ /*
+ * a0: offset
+ * a1: current __start___ex_table
+ * a2: current __stop___ex_table
+ */
+1: beq a1, a2, 996f
+ PTR_L t0, 0(a1)
+ PTR_ADDU t0, a0
+ PTR_S t0, 0(a1)
+ LONG_ADDIU a1, PTRSIZE
+ b 1b
+
+996:
+ /* get current _relocation_start address */
+ PTR_LA a1, _relocation_start
+ PTR_ADDU a1, a0
+
+ /*
+ * a0: offset
+ * a1: _relocation_start[]
+ * a2: offset >> 16, to relocate R_MIPS_HI16
+ * a3: current _text
+ * t0: to load _relocation_start[]
+ * t1: relocation type
+ * t2: current relocate position
+ * t3: temporarily
+ * t8: 0x00ffffff, mask, to get relocate position
+ * t9: offset >> 2, to relocate R_MIPS_26
+ */
+ PTR_LI t8, 0xffffff
+ LONG_SRL t9, a0, 2
+ LONG_SRL a2, a0, 16
+1: lw t0, 0(a1)
+ beqz t0, 997f
+ LONG_SRL t1, t0, 24
+ and t1, 0xff
+ and t2, t0, t8
+ LONG_SLL t2, 2
+ PTR_ADDU t2, a3
+
+#ifdef CONFIG_64BIT
+ li t3, R_MIPS_64
+ beq t1, t3, 964f
+#endif
+ li t3, R_MIPS_32
+ beq t1, t3, 932f
+ li t3, R_MIPS_26
+ beq t1, t3, 926f
+ li t3, R_MIPS_HI16
+ beq t1, t3, 916f
+ b 999f
+
+#ifdef CONFIG_64BIT
+964:
+ ld t3, 0(t2)
+ LONG_ADDU t3, a0
+ sd t3, 0(t2)
+ LONG_ADDIU a1, 4
+ b 1b
+#endif
+
+932:
+ lw t3, 0(t2)
+ LONG_ADDU t3, a0
+ sw t3, 0(t2)
+ LONG_ADDIU a1, 4
+ b 1b
+
+926:
+ lw t3, 0(t2)
+ LONG_ADDU t3, t9
+ sw t3, 0(t2)
+ LONG_ADDIU a1, 4
+ b 1b
+
+916:
+ lw t3, 0(t2)
+ LONG_ADDU t3, a2
+ sw t3, 0(t2)
+ LONG_ADDIU a1, 4
+ b 1b
+
+997:
+ /* Complete! And flush i-cache */
+1: PTR_LA a0, _text
+ PTR_LA a1, _end
+ synci 0(a0)
+ rdhwr t0, $1
+ beqz t0, 998f
+ PTR_ADDU a0, t0
+ PTR_SUBU t0, a1, a0
+ bgtz t0, 1b
+
+998:
+ sync
+
+999:
+
+#ifdef SMP_IN_KERNEL_ENTRY
+ PTR_LA a0, relocate_finished
+ LONG_S zero, 0(a0)
+#endif
+
+ /* Restore args */
+ move a0, s0
+ move a1, s1
+ move a2, s2
+ move a3, s3
+ .set pop
+ .endm
__REF
@@ -108,6 +262,10 @@ NESTED(kernel_entry, 16, sp) # kernel entry point
smp_in_kernel_entry_handle
#endif
+#ifdef CONFIG_RELOCATABLE
+ do_relocate_kernel
+#endif
+
PTR_LA t0, __bss_start # clear .bss
LONG_S zero, (t0)
PTR_LA t1, __bss_stop - LONGSIZE
--
2.1.0
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