[Xen-devel] [RFC v2 11/23] x86/acpi: Adapt assembly for PIE support

[Thomas Garnier <thgarnie@xxxxxxxxxx>]

Change the assembly code to use only relative references of symbols for the
kernel to be PIE compatible.

Position Independent Executable (PIE) support will allow to extended the
KASLR randomization range below the -2G memory limit.

Signed-off-by: Thomas Garnier <thgarnie@xxxxxxxxxx>
---
 arch/x86/kernel/acpi/wakeup_64.S | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S
index 50b8ed0317a3..472659c0f811 100644
--- a/arch/x86/kernel/acpi/wakeup_64.S
+++ b/arch/x86/kernel/acpi/wakeup_64.S
@@ -14,7 +14,7 @@
         * Hooray, we are in Long 64-bit mode (but still running in low memory)
         */
 ENTRY(wakeup_long64)
-       movq    saved_magic, %rax
+       movq    saved_magic(%rip), %rax
        movq    $0x123456789abcdef0, %rdx
        cmpq    %rdx, %rax
        jne     bogus_64_magic
@@ -25,14 +25,14 @@ ENTRY(wakeup_long64)
        movw    %ax, %es
        movw    %ax, %fs
        movw    %ax, %gs
-       movq    saved_rsp, %rsp
+       movq    saved_rsp(%rip), %rsp
 
-       movq    saved_rbx, %rbx
-       movq    saved_rdi, %rdi
-       movq    saved_rsi, %rsi
-       movq    saved_rbp, %rbp
+       movq    saved_rbx(%rip), %rbx
+       movq    saved_rdi(%rip), %rdi
+       movq    saved_rsi(%rip), %rsi
+       movq    saved_rbp(%rip), %rbp
 
-       movq    saved_rip, %rax
+       movq    saved_rip(%rip), %rax
        jmp     *%rax
 ENDPROC(wakeup_long64)
 
@@ -45,7 +45,7 @@ ENTRY(do_suspend_lowlevel)
        xorl    %eax, %eax
        call    save_processor_state
 
-       movq    $saved_context, %rax
+       leaq    saved_context(%rip), %rax
        movq    %rsp, pt_regs_sp(%rax)
        movq    %rbp, pt_regs_bp(%rax)
        movq    %rsi, pt_regs_si(%rax)
@@ -64,13 +64,14 @@ ENTRY(do_suspend_lowlevel)
        pushfq
        popq    pt_regs_flags(%rax)
 
-       movq    $.Lresume_point, saved_rip(%rip)
+       leaq    .Lresume_point(%rip), %rax
+       movq    %rax, saved_rip(%rip)
 
-       movq    %rsp, saved_rsp
-       movq    %rbp, saved_rbp
-       movq    %rbx, saved_rbx
-       movq    %rdi, saved_rdi
-       movq    %rsi, saved_rsi
+       movq    %rsp, saved_rsp(%rip)
+       movq    %rbp, saved_rbp(%rip)
+       movq    %rbx, saved_rbx(%rip)
+       movq    %rdi, saved_rdi(%rip)
+       movq    %rsi, saved_rsi(%rip)
 
        addq    $8, %rsp
        movl    $3, %edi
@@ -82,7 +83,7 @@ ENTRY(do_suspend_lowlevel)
        .align 4
 .Lresume_point:
        /* We don't restore %rax, it must be 0 anyway */
-       movq    $saved_context, %rax
+       leaq    saved_context(%rip), %rax
        movq    saved_context_cr4(%rax), %rbx
        movq    %rbx, %cr4
        movq    saved_context_cr3(%rax), %rbx
-- 
2.14.0.434.g98096fd7a8-goog


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