Hi,
On 16/06/2023 21:24, Andrew Cooper wrote:
--- /dev/null
+++ b/xen/arch/ppc/ppc64/head.S
@@ -0,0 +1,27 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+
+.section .text.header, "ax", %progbits
+
+ENTRY(start)
+ /*
+ * Depending on how we were booted, the CPU could be running in either
+ * Little Endian or Big Endian mode. The following trampoline from Linux
+ * cleverly uses an instruction that encodes to a NOP if the CPU's
+ * endianness matches the assumption of the assembler (LE, in our case)
+ * or a branch to code that performs the endian switch in the other case.
+ */
+ tdi 0, 0, 0x48 /* Reverse endian of b . + 8 */
+ b . + 44 /* Skip trampoline if endian is good */
+ .long 0xa600607d /* mfmsr r11 */
+ .long 0x01006b69 /* xori r11,r11,1 */
+ .long 0x00004039 /* li r10,0 */
+ .long 0x6401417d /* mtmsrd r10,1 */
+ .long 0x05009f42 /* bcl 20,31,$+4 */
+ .long 0xa602487d /* mflr r10 */
+ .long 0x14004a39 /* addi r10,r10,20 */
+ .long 0xa6035a7d /* mtsrr0 r10 */
+ .long 0xa6037b7d /* mtsrr1 r11 */
+ .long 0x2400004c /* rfid */
+
+ /* Now that the endianness is confirmed, continue */
+1: b 1b
.size start, . - start
.type start, %function
Shouldn't we introduce ENDPROC()/END() to avoid open-coding these two
lines everywhere?
Cheers,
--
Julien Grall
