Changes since V1:
https://lore.kernel.org/linux-riscv/[email protected]/
- the old Patch2 in V1 had been merged to riscv/fixes, so take it out of this series
- Patch1 : replace `.align 2` with `.balign 4` as Andreas suggested
- Patch2 : fix the conflict caused by commit a72ab0361110 ("riscv/purgatory: Disable CFI")
riscv: kexec: Cleanup riscv_kexec_relocate (Patch1)
==================================================
For readability and simplicity, cleanup the riscv_kexec_relocate code:
- Re-sort the first 4 `mv` instructions against `riscv_kexec_method()`
- Eliminate registers for debugging (s9,s10,s11) and storing const-value (s5,s6)
- Replace `jalr` with `jr` for no-link jump
riscv: kexec: Remove -fPIE for PURGATORY_CFLAGS (Patch2 : the Patch3 in V1)
==========================================================================
With CONFIG_RELOCATABLE enabled, KBUILD_CFLAGS had a -fPIE option
and then the purgatory/string.o was built to reference _ctype symbol
via R_RISCV_GOT_HI20 relocations which can't be handled by purgatory.
As a consequence, the kernel failed kexec_load_file() with:
[ 880.386562] kexec_image: The entry point of kernel at 0x80200000
[ 880.388650] kexec_image: Unknown rela relocation: 20
[ 880.389173] kexec_image: Error loading purgatory ret=-8
So remove the -fPIE option for PURGATORY_CFLAGS to generate
R_RISCV_PCREL_HI20 relocations type making puragtory work as it was.
Song Shuai (2):
riscv: kexec: Cleanup riscv_kexec_relocate
riscv: kexec: Remove -fPIE for PURGATORY_CFLAGS
arch/riscv/kernel/kexec_relocate.S | 54 +++++++++++++-----------------
arch/riscv/purgatory/Makefile | 4 +++
2 files changed, 28 insertions(+), 30 deletions(-)
--
2.20.1
For readability and simplicity, cleanup the riscv_kexec_relocate code:
- Re-sort the first 4 `mv` instructions against `riscv_kexec_method()`
- Eliminate registers for debugging (s9,s10,s11) and storing const-value (s5,s6)
- Replace `jalr` with `jr` for no-link jump
I tested this on Qemu virt machine and works as it was.
Signed-off-by: Song Shuai <[email protected]>
---
arch/riscv/kernel/kexec_relocate.S | 54 +++++++++++++-----------------
1 file changed, 24 insertions(+), 30 deletions(-)
diff --git a/arch/riscv/kernel/kexec_relocate.S b/arch/riscv/kernel/kexec_relocate.S
index 059c5e216ae7..ece5591abc4e 100644
--- a/arch/riscv/kernel/kexec_relocate.S
+++ b/arch/riscv/kernel/kexec_relocate.S
@@ -17,27 +17,17 @@ SYM_CODE_START(riscv_kexec_relocate)
* s1: (const) Phys address to jump to after relocation
* s2: (const) Phys address of the FDT image
* s3: (const) The hartid of the current hart
- * s4: Pointer to the destination address for the relocation
- * s5: (const) Number of words per page
- * s6: (const) 1, used for subtraction
- * s7: (const) kernel_map.va_pa_offset, used when switching MMU off
- * s8: (const) Physical address of the main loop
- * s9: (debug) indirection page counter
- * s10: (debug) entry counter
- * s11: (debug) copied words counter
+ * s4: (const) kernel_map.va_pa_offset, used when switching MMU off
+ * s5: Pointer to the destination address for the relocation
+ * s6: (const) Physical address of the main loop
*/
mv s0, a0
mv s1, a1
mv s2, a2
mv s3, a3
- mv s4, zero
- li s5, (PAGE_SIZE / RISCV_SZPTR)
- li s6, 1
- mv s7, a4
- mv s8, zero
- mv s9, zero
- mv s10, zero
- mv s11, zero
+ mv s4, a4
+ mv s5, zero
+ mv s6, zero
/* Disable / cleanup interrupts */
csrw CSR_SIE, zero
@@ -52,21 +42,27 @@ SYM_CODE_START(riscv_kexec_relocate)
* the start of the loop below so that we jump there in
* any case.
*/
- la s8, 1f
- sub s8, s8, s7
- csrw CSR_STVEC, s8
+ la s6, 1f
+ sub s6, s6, s4
+ csrw CSR_STVEC, s6
+
+ /*
+ * With C-extension, here we get 42 Bytes and the next
+ * .balign directive would pad zeros here up to 44 Bytes.
+ * So manually put a nop here to avoid zeros padding.
+ */
+ nop
/* Process entries in a loop */
-.align 2
+.balign 4
1:
- addi s10, s10, 1
REG_L t0, 0(s0) /* t0 = *image->entry */
addi s0, s0, RISCV_SZPTR /* image->entry++ */
/* IND_DESTINATION entry ? -> save destination address */
andi t1, t0, 0x1
beqz t1, 2f
- andi s4, t0, ~0x1
+ andi s5, t0, ~0x1
j 1b
2:
@@ -74,9 +70,8 @@ SYM_CODE_START(riscv_kexec_relocate)
andi t1, t0, 0x2
beqz t1, 2f
andi s0, t0, ~0x2
- addi s9, s9, 1
csrw CSR_SATP, zero
- jalr zero, s8, 0
+ jr s6
2:
/* IND_DONE entry ? -> jump to done label */
@@ -92,14 +87,13 @@ SYM_CODE_START(riscv_kexec_relocate)
andi t1, t0, 0x8
beqz t1, 1b /* Unknown entry type, ignore it */
andi t0, t0, ~0x8
- mv t3, s5 /* i = num words per page */
+ li t3, (PAGE_SIZE / RISCV_SZPTR) /* i = num words per page */
3: /* copy loop */
REG_L t1, (t0) /* t1 = *src_ptr */
- REG_S t1, (s4) /* *dst_ptr = *src_ptr */
+ REG_S t1, (s5) /* *dst_ptr = *src_ptr */
addi t0, t0, RISCV_SZPTR /* stc_ptr++ */
- addi s4, s4, RISCV_SZPTR /* dst_ptr++ */
- sub t3, t3, s6 /* i-- */
- addi s11, s11, 1 /* c++ */
+ addi s5, s5, RISCV_SZPTR /* dst_ptr++ */
+ addi t3, t3, -0x1 /* i-- */
beqz t3, 1b /* copy done ? */
j 3b
@@ -146,7 +140,7 @@ SYM_CODE_START(riscv_kexec_relocate)
*/
fence.i
- jalr zero, a2, 0
+ jr a2
SYM_CODE_END(riscv_kexec_relocate)
riscv_kexec_relocate_end:
--
2.20.1
With CONFIG_RELOCATABLE enabled, KBUILD_CFLAGS had a -fPIE option
and then the purgatory/string.o was built to reference _ctype symbol
via R_RISCV_GOT_HI20 relocations which can't be handled by purgatory.
As a consequence, the kernel failed kexec_load_file() with:
[ 880.386562] kexec_image: The entry point of kernel at 0x80200000
[ 880.388650] kexec_image: Unknown rela relocation: 20
[ 880.389173] kexec_image: Error loading purgatory ret=-8
So remove the -fPIE option for PURGATORY_CFLAGS to generate
R_RISCV_PCREL_HI20 relocations type making puragtory work as it was.
Fixes: 39b33072941f ("riscv: Introduce CONFIG_RELOCATABLE")
Signed-off-by: Song Shuai <[email protected]>
---
arch/riscv/purgatory/Makefile | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/arch/riscv/purgatory/Makefile b/arch/riscv/purgatory/Makefile
index 9e6476719abb..982fc8e77108 100644
--- a/arch/riscv/purgatory/Makefile
+++ b/arch/riscv/purgatory/Makefile
@@ -81,6 +81,10 @@ ifdef CONFIG_CFI_CLANG
PURGATORY_CFLAGS_REMOVE += $(CC_FLAGS_CFI)
endif
+ifdef CONFIG_RELOCATABLE
+PURGATORY_CFLAGS_REMOVE += -fPIE
+endif
+
CFLAGS_REMOVE_purgatory.o += $(PURGATORY_CFLAGS_REMOVE)
CFLAGS_purgatory.o += $(PURGATORY_CFLAGS)
--
2.20.1