Break down BL1 AArch64 synchronous exception handler
The AArch64 synchronous exception vector code in BL1 is almost
reaching its architectural limit of 32 instructions. This means
there is very little space for this code to grow.
This patch reduces the size of the exception vector code by
moving most of its code in a function to which we branch from
SynchronousExceptionA64.
Change-Id: Ib35351767a685fb2c2398029d32e54026194f7ed
diff --git a/bl1/aarch64/bl1_exceptions.S b/bl1/aarch64/bl1_exceptions.S
index 1ca3a6c..ca86107 100644
--- a/bl1/aarch64/bl1_exceptions.S
+++ b/bl1/aarch64/bl1_exceptions.S
@@ -115,51 +115,13 @@
/* Enable the SError interrupt */
msr daifclr, #DAIF_ABT_BIT
- /* ------------------------------------------------
- * Only a single SMC exception from BL2 to ask
- * BL1 to pass EL3 control to BL31 is expected
- * here.
- * It expects X0 with RUN_IMAGE SMC function id
- * X1 with address of a entry_point_info_t structure
- * describing the BL3-1 entrypoint
- * ------------------------------------------------
- */
- mov x19, x0
- mov x20, x1
-
- mrs x0, esr_el3
- ubfx x1, x0, #ESR_EC_SHIFT, #ESR_EC_LENGTH
- cmp x1, #EC_AARCH64_SMC
- b.ne panic
+ /* Expect only SMC exceptions */
+ mrs x19, esr_el3
+ ubfx x20, x19, #ESR_EC_SHIFT, #ESR_EC_LENGTH
+ cmp x20, #EC_AARCH64_SMC
+ b.ne unexpected_sync_exception
- mov x0, #RUN_IMAGE
- cmp x19, x0
- b.ne panic
-
- mov x0, x20
- bl display_boot_progress
-
- ldp x0, x1, [x20, #ENTRY_POINT_INFO_PC_OFFSET]
- msr elr_el3, x0
- msr spsr_el3, x1
- ubfx x0, x1, #MODE_EL_SHIFT, #2
- cmp x0, #MODE_EL3
- b.ne panic
-
- bl disable_mmu_icache_el3
- tlbi alle3
-
- ldp x6, x7, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x30)]
- ldp x4, x5, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x20)]
- ldp x2, x3, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x10)]
- ldp x0, x1, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x0)]
- eret
-panic:
- mov x0, #SYNC_EXCEPTION_AARCH64
- bl plat_report_exception
-
- wfi
- b panic
+ b smc_handler64
check_vector_size SynchronousExceptionA64
.align 7
@@ -214,3 +176,46 @@
bl plat_report_exception
b SErrorA32
check_vector_size SErrorA32
+
+
+func smc_handler64
+ /* ---------------------------------------------------------------------
+ * Only a single SMC exception from BL2 to ask BL1 to pass EL3 control
+ * to BL31 is expected here. It expects:
+ * - X0 with RUN_IMAGE SMC function ID;
+ * - X1 with the address of a entry_point_info_t structure describing
+ * the BL31 entrypoint.
+ * ---------------------------------------------------------------------
+ */
+ mov x19, x0
+ mov x20, x1
+
+ mov x0, #RUN_IMAGE
+ cmp x19, x0
+ b.ne unexpected_sync_exception
+
+ mov x0, x20
+ bl display_boot_progress
+
+ ldp x0, x1, [x20, #ENTRY_POINT_INFO_PC_OFFSET]
+ msr elr_el3, x0
+ msr spsr_el3, x1
+ ubfx x0, x1, #MODE_EL_SHIFT, #2
+ cmp x0, #MODE_EL3
+ b.ne unexpected_sync_exception
+
+ bl disable_mmu_icache_el3
+ tlbi alle3
+
+ ldp x6, x7, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x30)]
+ ldp x4, x5, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x20)]
+ ldp x2, x3, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x10)]
+ ldp x0, x1, [x20, #(ENTRY_POINT_INFO_ARGS_OFFSET + 0x0)]
+ eret
+endfunc smc_handler64
+
+unexpected_sync_exception:
+ mov x0, #SYNC_EXCEPTION_AARCH64
+ bl plat_report_exception
+ wfi
+ b unexpected_sync_exception