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Subject[PATCH v8 07/13] arm64: kexec_file: invoke the kernel without purgatory
Date
On arm64, purugatory would do almosty nothing. So just invoke the second
kernel by jumping into the entry code directly.

While, in this case, cpu_soft_restart() must be called in a specific way,
it still stays compatible with kexec as far as the fifth argument is null.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
arch/arm64/kernel/cpu-reset.S | 6 +++---
arch/arm64/kernel/machine_kexec.c | 11 +++++++++--
arch/arm64/kernel/relocate_kernel.S | 3 ++-
3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/arch/arm64/kernel/cpu-reset.S b/arch/arm64/kernel/cpu-reset.S
index 8021b46c9743..46fd9ea66ae8 100644
--- a/arch/arm64/kernel/cpu-reset.S
+++ b/arch/arm64/kernel/cpu-reset.S
@@ -24,9 +24,9 @@
*
* @el2_switch: Flag to indicate a swich to EL2 is needed.
* @entry: Location to jump to for soft reset.
- * arg0: First argument passed to @entry.
- * arg1: Second argument passed to @entry.
- * arg2: Third argument passed to @entry.
+ * arg0: First argument passed to @entry. (rellocator's address)
+ * arg1: Second argument passed to @entry.(physcal kernel entry)
+ * arg2: Third argument passed to @entry. (physical dtb address)
*
* Put the CPU into the same state as it would be if it had been reset, and
* branch to what would be the reset vector. It must be executed with the
diff --git a/arch/arm64/kernel/machine_kexec.c b/arch/arm64/kernel/machine_kexec.c
index f76ea92dff91..f7dbba00be10 100644
--- a/arch/arm64/kernel/machine_kexec.c
+++ b/arch/arm64/kernel/machine_kexec.c
@@ -205,10 +205,17 @@ void machine_kexec(struct kimage *kimage)
* uses physical addressing to relocate the new image to its final
* position and transfers control to the image entry point when the
* relocation is complete.
+ * In case of kexec_file_load syscall, we directly start the kernel,
+ * skipping purgatory.
*/
-
cpu_soft_restart(kimage != kexec_crash_image,
- reboot_code_buffer_phys, kimage->head, kimage->start, 0);
+ reboot_code_buffer_phys, kimage->head, kimage->start,
+#ifdef CONFIG_KEXEC_FILE
+ kimage->purgatory_info.purgatory_buf ?
+ 0 : kimage->arch.dtb_mem);
+#else
+ 0);
+#endif

BUG(); /* Should never get here. */
}
diff --git a/arch/arm64/kernel/relocate_kernel.S b/arch/arm64/kernel/relocate_kernel.S
index f407e422a720..95fd94209aae 100644
--- a/arch/arm64/kernel/relocate_kernel.S
+++ b/arch/arm64/kernel/relocate_kernel.S
@@ -32,6 +32,7 @@
ENTRY(arm64_relocate_new_kernel)

/* Setup the list loop variables. */
+ mov x18, x2 /* x18 = dtb address */
mov x17, x1 /* x17 = kimage_start */
mov x16, x0 /* x16 = kimage_head */
raw_dcache_line_size x15, x0 /* x15 = dcache line size */
@@ -107,7 +108,7 @@ ENTRY(arm64_relocate_new_kernel)
isb

/* Start new image. */
- mov x0, xzr
+ mov x0, x18
mov x1, xzr
mov x2, xzr
mov x3, xzr
--
2.16.2
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