rework general purpose registers save and restore
The runtime exception handling assembler code used magic numbers for
saving and restoring the general purpose register context on stack
memory. The memory is interpreted as a 'gp_regs' structure and the
magic numbers are offsets to members of this structure. This patch
replaces the magic number offsets with constants. It also adds compile
time assertions to prevent an incorrect assembler view of this
structure.
Change-Id: Ibf125bfdd62ba3a33e58c5f1d71f8c229720781c
diff --git a/bl31/aarch64/runtime_exceptions.S b/bl31/aarch64/runtime_exceptions.S
index 6d086e0..52163b8 100644
--- a/bl31/aarch64/runtime_exceptions.S
+++ b/bl31/aarch64/runtime_exceptions.S
@@ -202,47 +202,3 @@
.align 7
-save_regs:; .type save_regs, %function
- sub sp, sp, #0x100
- stp x0, x1, [sp, #0x0]
- stp x2, x3, [sp, #0x10]
- stp x4, x5, [sp, #0x20]
- stp x6, x7, [sp, #0x30]
- stp x8, x9, [sp, #0x40]
- stp x10, x11, [sp, #0x50]
- stp x12, x13, [sp, #0x60]
- stp x14, x15, [sp, #0x70]
- stp x16, x17, [sp, #0x80]
- stp x18, x19, [sp, #0x90]
- stp x20, x21, [sp, #0xa0]
- stp x22, x23, [sp, #0xb0]
- stp x24, x25, [sp, #0xc0]
- stp x26, x27, [sp, #0xd0]
- mrs x0, sp_el0
- stp x28, x0, [sp, #0xe0]
- mrs x0, spsr_el3
- str x0, [sp, #0xf0]
- ret
-
-
-restore_regs:; .type restore_regs, %function
- ldr x9, [sp, #0xf0]
- msr spsr_el3, x9
- ldp x28, x9, [sp, #0xe0]
- msr sp_el0, x9
- ldp x26, x27, [sp, #0xd0]
- ldp x24, x25, [sp, #0xc0]
- ldp x22, x23, [sp, #0xb0]
- ldp x20, x21, [sp, #0xa0]
- ldp x18, x19, [sp, #0x90]
- ldp x16, x17, [sp, #0x80]
- ldp x14, x15, [sp, #0x70]
- ldp x12, x13, [sp, #0x60]
- ldp x10, x11, [sp, #0x50]
- ldp x8, x9, [sp, #0x40]
- ldp x6, x7, [sp, #0x30]
- ldp x4, x5, [sp, #0x20]
- ldp x2, x3, [sp, #0x10]
- ldp x0, x1, [sp, #0x0]
- add sp, sp, #0x100
- ret
diff --git a/include/asm_macros.S b/include/asm_macros.S
index 0067ca6..786c52a 100644
--- a/include/asm_macros.S
+++ b/include/asm_macros.S
@@ -55,14 +55,14 @@
.macro exception_entry func
- stp x29, x30, [sp, #-0x10]!
+ stp x29, x30, [sp, #-(SIZEOF_GPREGS - GPREGS_FP_OFF)]!
bl \func
.endm
.macro exception_exit func
bl \func
- ldp x29, x30, [sp], #0x10
+ ldp x29, x30, [sp], #(SIZEOF_GPREGS - GPREGS_FP_OFF)
.endm
diff --git a/include/bl_common.h b/include/bl_common.h
index 3504d04..0af98d6 100644
--- a/include/bl_common.h
+++ b/include/bl_common.h
@@ -63,6 +63,13 @@
******************************************************************************/
#define EL_CHANGE_MEM_SIZE (sizeof(meminfo) + sizeof(el_change_info))
+/*******************************************************************************
+ * Macro to flag a compile time assertion. It uses the preprocessor to generate
+ * an invalid C construct if 'cond' evaluates to false.
+ * The following compilation error is triggered if the assertion fails:
+ * "error: size of array 'msg' is negative"
+ ******************************************************************************/
+#define CASSERT(cond, msg) typedef char msg[(cond) ? 0 : -1]
#ifndef __ASSEMBLY__
/*******************************************************************************
diff --git a/include/runtime_svc.h b/include/runtime_svc.h
index 3ccbe88..61c2d27 100644
--- a/include/runtime_svc.h
+++ b/include/runtime_svc.h
@@ -31,6 +31,7 @@
#ifndef __RUNTIME_SVC_H__
#define __RUNTIME_SVC_H__
#include <psci.h>
+#include <bl_common.h>
/*******************************************************************************
* Bit definitions inside the function id as per the SMC calling convention
@@ -72,6 +73,45 @@
#define FIQ_AARCH32 0xe
#define SERROR_AARCH32 0xf
+/*******************************************************************************
+ * Constants that allow assembler code to access members of the 'gp_regs'
+ * structure at their correct offsets.
+ ******************************************************************************/
+#define SIZEOF_GPREGS 0x110
+#define GPREGS_X0_OFF 0x0
+#define GPREGS_X1_OFF 0x8
+#define GPREGS_X2_OFF 0x10
+#define GPREGS_X3_OFF 0x18
+#define GPREGS_X4_OFF 0x20
+#define GPREGS_X5_OFF 0x28
+#define GPREGS_X6_OFF 0x30
+#define GPREGS_X7_OFF 0x38
+#define GPREGS_X8_OFF 0x40
+#define GPREGS_X9_OFF 0x48
+#define GPREGS_X10_OFF 0x50
+#define GPREGS_X11_OFF 0x58
+#define GPREGS_X12_OFF 0x60
+#define GPREGS_X13_OFF 0x68
+#define GPREGS_X14_OFF 0x70
+#define GPREGS_X15_OFF 0x78
+#define GPREGS_X16_OFF 0x80
+#define GPREGS_X17_OFF 0x88
+#define GPREGS_X18_OFF 0x90
+#define GPREGS_X19_OFF 0x98
+#define GPREGS_X20_OFF 0xA0
+#define GPREGS_X21_OFF 0xA8
+#define GPREGS_X22_OFF 0xB0
+#define GPREGS_X23_OFF 0xB8
+#define GPREGS_X24_OFF 0xC0
+#define GPREGS_X25_OFF 0xC8
+#define GPREGS_X26_OFF 0xD0
+#define GPREGS_X27_OFF 0xD8
+#define GPREGS_X28_OFF 0xE0
+#define GPREGS_SP_EL0_OFF 0xE8
+#define GPREGS_SPSR_OFF 0xF0
+#define GPREGS_FP_OFF 0x100
+#define GPREGS_LR_OFF 0x108
+
#ifndef __ASSEMBLY__
typedef struct {
@@ -106,10 +146,24 @@
unsigned long x28;
unsigned long sp_el0;
unsigned long spsr;
- unsigned long fp;
+ /*
+ * Alignment constraint which allows save & restore of fp & lr on the
+ * stack during exception handling
+ */
+ unsigned long fp __attribute__((__aligned__(16)));
unsigned long lr;
-} gp_regs;
+} __attribute__((__aligned__(16))) gp_regs;
+/*******************************************************************************
+ * Compile time assertions to ensure that:
+ * 1) the assembler code's view of the size of the 'gp_regs' data structure is
+ * the same as the actual size of this data structure.
+ * 2) the assembler code's view of the offset of the frame pointer member of
+ * the 'gp_regs' structure is the same as the actual offset of this member.
+ ******************************************************************************/
+CASSERT((sizeof(gp_regs) == SIZEOF_GPREGS), assert_sizeof_gpregs_mismatch);
+CASSERT(GPREGS_FP_OFF == __builtin_offsetof(gp_regs, fp), \
+ assert_gpregs_fp_offset_mismatch);
/*******************************************************************************
* Function & variable prototypes
diff --git a/lib/arch/aarch64/misc_helpers.S b/lib/arch/aarch64/misc_helpers.S
index 08a568e..c951d0e 100644
--- a/lib/arch/aarch64/misc_helpers.S
+++ b/lib/arch/aarch64/misc_helpers.S
@@ -29,6 +29,10 @@
*/
#include <arch_helpers.h>
+#include <runtime_svc.h>
+
+ .globl save_regs
+ .globl restore_regs
.globl enable_irq
.globl disable_irq
@@ -80,6 +84,51 @@
.section .text, "ax"
+save_regs:; .type save_regs, %function
+ sub sp, sp, #GPREGS_FP_OFF
+ stp x0, x1, [sp, #GPREGS_X0_OFF]
+ stp x2, x3, [sp, #GPREGS_X2_OFF]
+ stp x4, x5, [sp, #GPREGS_X4_OFF]
+ stp x6, x7, [sp, #GPREGS_X6_OFF]
+ stp x8, x9, [sp, #GPREGS_X8_OFF]
+ stp x10, x11, [sp, #GPREGS_X10_OFF]
+ stp x12, x13, [sp, #GPREGS_X12_OFF]
+ stp x14, x15, [sp, #GPREGS_X14_OFF]
+ stp x16, x17, [sp, #GPREGS_X16_OFF]
+ stp x18, x19, [sp, #GPREGS_X18_OFF]
+ stp x20, x21, [sp, #GPREGS_X20_OFF]
+ stp x22, x23, [sp, #GPREGS_X22_OFF]
+ stp x24, x25, [sp, #GPREGS_X24_OFF]
+ stp x26, x27, [sp, #GPREGS_X26_OFF]
+ mrs x0, sp_el0
+ stp x28, x0, [sp, #GPREGS_X28_OFF]
+ mrs x0, spsr_el3
+ str x0, [sp, #GPREGS_SPSR_OFF]
+ ret
+
+
+restore_regs:; .type restore_regs, %function
+ ldr x9, [sp, #GPREGS_SPSR_OFF]
+ msr spsr_el3, x9
+ ldp x28, x9, [sp, #GPREGS_X28_OFF]
+ msr sp_el0, x9
+ ldp x26, x27, [sp, #GPREGS_X26_OFF]
+ ldp x24, x25, [sp, #GPREGS_X24_OFF]
+ ldp x22, x23, [sp, #GPREGS_X22_OFF]
+ ldp x20, x21, [sp, #GPREGS_X20_OFF]
+ ldp x18, x19, [sp, #GPREGS_X18_OFF]
+ ldp x16, x17, [sp, #GPREGS_X16_OFF]
+ ldp x14, x15, [sp, #GPREGS_X14_OFF]
+ ldp x12, x13, [sp, #GPREGS_X12_OFF]
+ ldp x10, x11, [sp, #GPREGS_X10_OFF]
+ ldp x8, x9, [sp, #GPREGS_X8_OFF]
+ ldp x6, x7, [sp, #GPREGS_X6_OFF]
+ ldp x4, x5, [sp, #GPREGS_X4_OFF]
+ ldp x2, x3, [sp, #GPREGS_X2_OFF]
+ ldp x0, x1, [sp, #GPREGS_X0_OFF]
+ add sp, sp, #GPREGS_FP_OFF
+ ret
+
get_afflvl_shift:; .type get_afflvl_shift, %function
cmp x0, #3
cinc x0, x0, eq