[Xen-devel] [PATCH 02/14] xen: arm: tweak arm64 stack frame layout

[Ian Campbell <ijc@xxxxxxxxxxxxxx>]

From: Ian Campbell <ian.campbell@xxxxxxxxxx>

Correct definition of UREGS_kernel_sizeof and use it.

Correct adjustment of stack on entry and exit.

Add 64-bit versions of the build time checks for stack pointer alignment
correctness when pushing the stack frames.

Lastly, correct the padding in the stack frames to properly align the inner and
outer frames and also avoid an unnecessary 64bit padding field.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 xen/arch/arm/arm64/asm-offsets.c      |    2 +-
 xen/arch/arm/arm64/entry.S            |    9 +++++----
 xen/arch/arm/domain.c                 |    2 ++
 xen/arch/arm/traps.c                  |    7 +++++++
 xen/include/asm-arm/arm64/processor.h |    7 +++----
 5 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/xen/arch/arm/arm64/asm-offsets.c b/xen/arch/arm/arm64/asm-offsets.c
index 7949e3e..7544082 100644
--- a/xen/arch/arm/arm64/asm-offsets.c
+++ b/xen/arch/arm/arm64/asm-offsets.c
@@ -39,7 +39,7 @@ void __dummy__(void)
    OFFSET(UREGS_SP_el1, struct cpu_user_regs, sp_el1);
    OFFSET(UREGS_ELR_el1, struct cpu_user_regs, elr_el1);
 
-   OFFSET(UREGS_kernel_sizeof, struct cpu_user_regs, cpsr);
+   OFFSET(UREGS_kernel_sizeof, struct cpu_user_regs, spsr_el1);
    DEFINE(UREGS_user_sizeof, sizeof(struct cpu_user_regs));
    BLANK();
 
diff --git a/xen/arch/arm/arm64/entry.S b/xen/arch/arm/arm64/entry.S
index 9d38088..a5fd608 100644
--- a/xen/arch/arm/arm64/entry.S
+++ b/xen/arch/arm/arm64/entry.S
@@ -34,7 +34,7 @@ lr      .req    x30             // link register
         mrs     x22, SP_el0
         str     x22, [x21]
 
-        add     x21, sp, #UREGS_ELR_el1
+        add     x21, sp, #UREGS_SP_el1
         mrs     x22, SP_el1
         mrs     x23, ELR_el1
         stp     x22, x23, [x21]
@@ -59,7 +59,7 @@ lr      .req    x30             // link register
  * Save state on entry to hypervisor
  */
         .macro  entry, hyp, compat
-        sub     sp, sp, #(UREGS_SPSR_el1 - UREGS_SP)
+        sub     sp, sp, #(UREGS_SPSR_el1 - UREGS_LR) /* CPSR, PC, SP, LR */
         push    x28, x29
         push    x26, x27
         push    x24, x25
@@ -78,7 +78,7 @@ lr      .req    x30             // link register
 
         .if \hyp == 1        /* Hypervisor mode */
 
-        add     x21, sp, #(UREGS_X0 - UREGS_SP)
+        add     x21, sp, #UREGS_kernel_sizeof
 
         .else                /* Guest mode */
 
@@ -213,7 +213,8 @@ ENTRY(return_to_hypervisor)
         pop     x26, x27
         pop     x28, x29
 
-        ldr     lr, [sp], #(UREGS_SPSR_el1 - UREGS_SP)
+        ldr     lr, [sp], #(UREGS_SPSR_el1 - UREGS_LR) /* CPSR, PC, SP, LR */
+
         eret
 
 /*
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index f369871..08bb132 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -419,6 +419,8 @@ int vcpu_initialise(struct vcpu *v)
 {
     int rc = 0;
 
+    BUILD_BUG_ON( sizeof(struct cpu_info) > STACK_SIZE );
+
     v->arch.stack = alloc_xenheap_pages(STACK_ORDER, 
MEMF_node(vcpu_to_node(v)));
     if ( v->arch.stack == NULL )
         return -ENOMEM;
diff --git a/xen/arch/arm/traps.c b/xen/arch/arm/traps.c
index a98a45e..6b19bc5 100644
--- a/xen/arch/arm/traps.c
+++ b/xen/arch/arm/traps.c
@@ -43,9 +43,16 @@
  * entry.S) and struct cpu_info (which lives at the bottom of a Xen
  * stack) must be doubleword-aligned in size.  */
 static inline void check_stack_alignment_constraints(void) {
+#ifdef CONFIG_ARM_64
+    BUILD_BUG_ON((sizeof (struct cpu_user_regs)) & 0xf);
+    BUILD_BUG_ON((offsetof(struct cpu_user_regs, spsr_el1)) & 0xf);
+    BUILD_BUG_ON((offsetof(struct cpu_user_regs, lr)) & 0xf);
+    BUILD_BUG_ON((sizeof (struct cpu_info)) & 0xf);
+#else
     BUILD_BUG_ON((sizeof (struct cpu_user_regs)) & 0x7);
     BUILD_BUG_ON((offsetof(struct cpu_user_regs, sp_usr)) & 0x7);
     BUILD_BUG_ON((sizeof (struct cpu_info)) & 0x7);
+#endif
 }
 
 static int debug_stack_lines = 20;
diff --git a/xen/include/asm-arm/arm64/processor.h 
b/xen/include/asm-arm/arm64/processor.h
index b4602fa..bf436c8 100644
--- a/xen/include/asm-arm/arm64/processor.h
+++ b/xen/include/asm-arm/arm64/processor.h
@@ -51,6 +51,7 @@ struct cpu_user_regs
     __DECL_REG(x27,          r11_fiq);
     __DECL_REG(x28,          r12_fiq);
     __DECL_REG(/* x29 */ fp, /* r13_fiq */ sp_fiq);
+
     __DECL_REG(/* x30 */ lr, /* r14_fiq */ lr_fiq);
 
     register_t sp; /* Valid for hypervisor frames */
@@ -59,7 +60,7 @@ struct cpu_user_regs
     __DECL_REG(pc,           pc32);             /* ELR_EL2 */
     uint32_t cpsr;                              /* SPSR_EL2 */
 
-    uint64_t pad0;
+    uint32_t pad0; /* Align end of kernel frame. */
 
     /* Outer guest frame only from here on... */
 
@@ -68,7 +69,7 @@ struct cpu_user_regs
         uint32_t spsr_svc;       /* AArch32 */
     };
 
-    uint32_t pad1; /* Align */
+    uint32_t pad1; /* Doubleword-align the user half of the frame */
 
     /* AArch32 guests only */
     uint32_t spsr_fiq, spsr_irq, spsr_und, spsr_abt;
@@ -76,8 +77,6 @@ struct cpu_user_regs
     /* AArch64 guests only */
     uint64_t sp_el0;
     uint64_t sp_el1, elr_el1;
-
-    uint64_t pad2; /* Doubleword-align the user half of the frame */
 };
 
 #undef __DECL_REG
-- 
1.7.10.4


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