@@ -117,6 +117,18 @@
#endif /* !CONFIG_EARLY_PRINTK */
+/*
+ * Pseudo-op for PC relative adr <reg>, <symbol> where <symbol> is
+ * within the range +/- 4GB of the PC.
+ *
+ * @dst: destination register (64 bit wide)
+ * @sym: name of the symbol
+ */
+.macro adr_l, dst, sym
+ adrp \dst, \sym
+ add \dst, \dst, :lo12:\sym
+.endm
+
/* Load the physical address of a symbol into xb */
.macro load_paddr xb, sym
ldr \xb, =\sym
@@ -895,11 +907,9 @@ ENTRY(efi_xen_start)
* Flush dcache covering current runtime addresses
* of xen text/data. Then flush all of icache.
*/
- adrp x1, _start
- add x1, x1, #:lo12:_start
+ adr_l x1, _start
mov x0, x1
- adrp x2, _end
- add x2, x2, #:lo12:_end
+ adr_l x2, _end
sub x1, x2, x1
bl __flush_dcache_area
Arm64 provides instructions to load a PC-relative address, but with some limitations: - adr is enable to cope with +/-1MB - adrp is enale to cope with +/-4GB but relative to a 4KB page address Because of that, the code requires to use 2 instructions to load any Xen symbol. To make the code more obvious, introducing a new macro adr_l is introduced. The new macro is used to replace a couple of open-coded use in efi_xen_start. The macro is copied from Linux 5.2-rc4. Signed-off-by: Julien Grall <julien.grall@arm.com> Acked-by: Stefano Stabellini <sstabellini@kernel.org> --- Changes in v3: - Fix typo in my e-mail address - Add Stefano's acked-by Changes in v2: - Patch added --- xen/arch/arm/arm64/head.S | 18 ++++++++++++++---- 1 file changed, 14 insertions(+), 4 deletions(-)