* [PATCH v2 2/5] MIPS: relocate: Use CONFIG_RANDOMIZE_BASE to enable kaslr
2021-04-12 12:28 [PATCH v2 0/5] MIPS: relocate: Add automatic relocation to CONFIG_RELOCATABLE Jinyang He
2021-04-12 12:28 ` [PATCH v2 1/5] MIPS: relocate: Only compile relocs when CONFIG_RELOCATABLE is enabled Jinyang He
@ 2021-04-12 12:28 ` Jinyang He
2021-04-12 12:28 ` [PATCH v2 3/5] MIPS: Jump to kernel linked address by PC relative way Jinyang He
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Jinyang He @ 2021-04-12 12:28 UTC (permalink / raw)
To: Thomas Bogendoerfer, Paul Burton; +Cc: linux-mips, linux-kernel
Currently, the difference between using CONFIG_RELOCATABLE and
CONFIG_RANDOMIZE_BASE is determine_relocation_address().
CONFIG_RANDOMIZE_BASE achieves randomization. CONFIG_RELOCATABLE
relocate the kernel is very limited, currently returns a constant.
Therefore, drop determine_relocation_address() if CONFIG_RELOCATABLE.
Rename relocate.c to kaslr.c and use CONFIG_RANDOMIZE_BASE to enable
the kaslr function.
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
arch/mips/cavium-octeon/smp.c | 8 ++++----
arch/mips/generic/init.c | 4 ++--
arch/mips/include/asm/bootinfo.h | 4 ++--
.../include/asm/mach-cavium-octeon/kernel-entry-init.h | 4 ++--
arch/mips/kernel/Makefile | 2 +-
arch/mips/kernel/head.S | 6 +++---
arch/mips/kernel/{relocate.c => kaslr.c} | 15 ---------------
7 files changed, 14 insertions(+), 29 deletions(-)
rename arch/mips/kernel/{relocate.c => kaslr.c} (97%)
diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c
index 66ce552..dfdbc79 100644
--- a/arch/mips/cavium-octeon/smp.c
+++ b/arch/mips/cavium-octeon/smp.c
@@ -28,9 +28,9 @@
volatile unsigned long octeon_processor_boot = 0xff;
volatile unsigned long octeon_processor_sp;
volatile unsigned long octeon_processor_gp;
-#ifdef CONFIG_RELOCATABLE
+#ifdef CONFIG_RANDOMIZE_BASE
volatile unsigned long octeon_processor_relocated_kernel_entry;
-#endif /* CONFIG_RELOCATABLE */
+#endif /* CONFIG_RANDOMIZE_BASE */
#ifdef CONFIG_HOTPLUG_CPU
uint64_t octeon_bootloader_entry_addr;
@@ -190,7 +190,7 @@ static void __init octeon_smp_setup(void)
}
-#ifdef CONFIG_RELOCATABLE
+#ifdef CONFIG_RANDOMIZE_BASE
int plat_post_relocation(long offset)
{
unsigned long entry = (unsigned long)kernel_entry;
@@ -200,7 +200,7 @@ int plat_post_relocation(long offset)
return 0;
}
-#endif /* CONFIG_RELOCATABLE */
+#endif /* CONFIG_RANDOMIZE_BASE */
/**
* Firmware CPU startup hook
diff --git a/arch/mips/generic/init.c b/arch/mips/generic/init.c
index 1842cdd..f7a4e29 100644
--- a/arch/mips/generic/init.c
+++ b/arch/mips/generic/init.c
@@ -82,7 +82,7 @@ void __init *plat_get_fdt(void)
return (void *)fdt;
}
-#ifdef CONFIG_RELOCATABLE
+#ifdef CONFIG_RANDOMIZE_BASE
void __init plat_fdt_relocated(void *new_location)
{
@@ -97,7 +97,7 @@ void __init plat_fdt_relocated(void *new_location)
fw_arg1 = (unsigned long)new_location;
}
-#endif /* CONFIG_RELOCATABLE */
+#endif /* CONFIG_RANDOMIZE_BASE */
void __init plat_mem_setup(void)
{
diff --git a/arch/mips/include/asm/bootinfo.h b/arch/mips/include/asm/bootinfo.h
index 5be10ece..6b37663 100644
--- a/arch/mips/include/asm/bootinfo.h
+++ b/arch/mips/include/asm/bootinfo.h
@@ -169,7 +169,7 @@ static inline void plat_swiotlb_setup(void) {}
*/
extern void *plat_get_fdt(void);
-#ifdef CONFIG_RELOCATABLE
+#ifdef CONFIG_RANDOMIZE_BASE
/**
* plat_fdt_relocated() - Update platform's information about relocated dtb
@@ -180,7 +180,7 @@ extern void *plat_get_fdt(void);
*/
void plat_fdt_relocated(void *new_location);
-#endif /* CONFIG_RELOCATABLE */
+#endif /* CONFIG_RANDOMIZE_BASE */
#endif /* CONFIG_USE_OF */
#endif /* _ASM_BOOTINFO_H */
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 c38b38c..e66767d 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
@@ -100,7 +100,7 @@
#
octeon_spin_wait_boot:
-#ifdef CONFIG_RELOCATABLE
+#ifdef CONFIG_RANDOMIZE_BASE
PTR_LA t0, octeon_processor_relocated_kernel_entry
LONG_L t0, (t0)
beq zero, t0, 1f
@@ -109,7 +109,7 @@
jr t0
nop
1:
-#endif /* CONFIG_RELOCATABLE */
+#endif /* CONFIG_RANDOMIZE_BASE */
# This is the variable where the next core to boot is stored
PTR_LA t0, octeon_processor_boot
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index b4a57f1..bf7ac86 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -92,7 +92,7 @@ obj-$(CONFIG_I8253) += i8253.o
obj-$(CONFIG_GPIO_TXX9) += gpio_txx9.o
-obj-$(CONFIG_RELOCATABLE) += relocate.o
+obj-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
obj-$(CONFIG_KEXEC) += machine_kexec.o relocate_kernel.o crash.o
obj-$(CONFIG_CRASH_DUMP) += crash_dump.o
diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S
index b825ed4..a25af1d 100644
--- a/arch/mips/kernel/head.S
+++ b/arch/mips/kernel/head.S
@@ -118,7 +118,7 @@ NESTED(kernel_entry, 16, sp) # kernel entry point
set_saved_sp sp, t0, t1
PTR_SUBU sp, 4 * SZREG # init stack pointer
-#ifdef CONFIG_RELOCATABLE
+#ifdef CONFIG_RANDOMIZE_BASE
/* Copy kernel and apply the relocations */
jal relocate_kernel
@@ -136,9 +136,9 @@ NESTED(kernel_entry, 16, sp) # kernel entry point
* newly sync'd icache.
*/
jr.hb v0
-#else /* !CONFIG_RELOCATABLE */
+#else /* !CONFIG_RANDOMIZE_BASE */
j start_kernel
-#endif /* !CONFIG_RELOCATABLE */
+#endif /* !CONFIG_RANDOMIZE_BASE */
END(kernel_entry)
#ifdef CONFIG_SMP
diff --git a/arch/mips/kernel/relocate.c b/arch/mips/kernel/kaslr.c
similarity index 97%
rename from arch/mips/kernel/relocate.c
rename to arch/mips/kernel/kaslr.c
index 499a535..6742d58 100644
--- a/arch/mips/kernel/relocate.c
+++ b/arch/mips/kernel/kaslr.c
@@ -188,8 +188,6 @@ static int __init relocate_exception_table(long offset)
return 0;
}
-#ifdef CONFIG_RANDOMIZE_BASE
-
static inline __init unsigned long rotate_xor(unsigned long hash,
const void *area, size_t size)
{
@@ -280,19 +278,6 @@ static inline void __init *determine_relocation_address(void)
return RELOCATED(dest);
}
-#else
-
-static inline void __init *determine_relocation_address(void)
-{
- /*
- * Choose a new address for the kernel
- * For now we'll hard code the destination
- */
- return (void *)0xffffffff81000000;
-}
-
-#endif
-
static inline int __init relocation_addr_valid(void *loc_new)
{
if ((unsigned long)loc_new & 0x0000ffff) {
--
2.1.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH v2 3/5] MIPS: Jump to kernel linked address by PC relative way
2021-04-12 12:28 [PATCH v2 0/5] MIPS: relocate: Add automatic relocation to CONFIG_RELOCATABLE Jinyang He
2021-04-12 12:28 ` [PATCH v2 1/5] MIPS: relocate: Only compile relocs when CONFIG_RELOCATABLE is enabled Jinyang He
2021-04-12 12:28 ` [PATCH v2 2/5] MIPS: relocate: Use CONFIG_RANDOMIZE_BASE to enable kaslr Jinyang He
@ 2021-04-12 12:28 ` Jinyang He
2021-04-12 12:28 ` [PATCH v2 4/5] MIPS: cavium-octeon: Execute the smp handle after jumping to kernel linked address Jinyang He
2021-04-12 12:28 ` [PATCH v2 5/5] MIPS: relocate: Add support to auto relocate kernel Jinyang He
4 siblings, 0 replies; 6+ messages in thread
From: Jinyang He @ 2021-04-12 12:28 UTC (permalink / raw)
To: Thomas Bogendoerfer, Paul Burton; +Cc: linux-mips, linux-kernel
Commit 15ad838d281b ("[MIPS] Always do the ARC64_TWIDDLE_PC thing.")
gives the kernel a chance to jump to the address the kernel is linked to.
It can be seen from the old records that this situation is usually a jump
from XPHYS to KSEG0. For example, kdump operation, kexec_start_address is
usually in XPHYS on Loongson64 platform. Jumping from XPHYS to KSEG0 is a
big jump. With the relocation, there may be small jumps. As follows,
+-----------+
| |
|___________|
| |
| _kernel |
| |
|_\0: |
| jr t0 |---+
| la t0, \0 | |
|___________| |
| | |
| | |
|___________| |
| | |
| kernel | |
| | |
|\0: |<--+
| jr t0 |
| la t0, \0 |
| |
|___________|
| |
+-----------+
_kernel is same as kernel, only the loaded address is different. They are
all in KSEG0. For kernel, `jr t0` is right operation and PC will jump to
\0. For _kernel, `jr t0` is dangerous operation and PC will not jump to
_\0 because `la t0, \0` target address is not PC relative.
This patch get the PC address by fixed `1:` (t0) and dynamic ra at
`1:` (t1). t0 determines the PC Region of the address where the kernel is
linked to. t1 determines the offset relative to the PC Region.
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
arch/mips/kernel/head.S | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
diff --git a/arch/mips/kernel/head.S b/arch/mips/kernel/head.S
index a25af1d..0186285 100644
--- a/arch/mips/kernel/head.S
+++ b/arch/mips/kernel/head.S
@@ -79,6 +79,9 @@ FEXPORT(__kernel_entry)
j kernel_entry
#endif /* CONFIG_BOOT_RAW */
+#define PC_REGION_SHIFT 28
+#define PC_REGION_MASK (~(1 << PC_REGION_SHIFT - 1))
+
__REF
NESTED(kernel_entry, 16, sp) # kernel entry point
@@ -89,9 +92,17 @@ NESTED(kernel_entry, 16, sp) # kernel entry point
/* We might not get launched at the address the kernel is linked to,
so we jump there. */
- PTR_LA t0, 0f
- jr t0
-0:
+ PTR_LA t0, 1f
+ bal 1f
+1: move t1, ra
+ PTR_LI t2, PC_REGION_MASK
+ and t0, t2
+ PTR_LI t2, ~PC_REGION_MASK
+ and t1, t2
+ or t0, t1
+ PTR_ADDIU t0, 2f-1b
+ jr t0
+2:
PTR_LA t0, __bss_start # clear .bss
LONG_S zero, (t0)
--
2.1.0
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH v2 5/5] MIPS: relocate: Add support to auto relocate kernel
2021-04-12 12:28 [PATCH v2 0/5] MIPS: relocate: Add automatic relocation to CONFIG_RELOCATABLE Jinyang He
` (3 preceding siblings ...)
2021-04-12 12:28 ` [PATCH v2 4/5] MIPS: cavium-octeon: Execute the smp handle after jumping to kernel linked address Jinyang He
@ 2021-04-12 12:28 ` Jinyang He
4 siblings, 0 replies; 6+ messages in thread
From: Jinyang He @ 2021-04-12 12:28 UTC (permalink / raw)
To: Thomas Bogendoerfer, Paul Burton; +Cc: linux-mips, linux-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@loongson.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
^ permalink raw reply related [flat|nested] 6+ messages in thread