[PATCH v1 05/27] x86: relocate_kernel - Adapt assembly for PIE support
From: Thomas Garnier via Virtualization <hidden>
Date: 2017-10-11 20:30:05
Subsystem:
the rest, x86 architecture (32-bit and 64-bit) · Maintainers:
Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen
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 <redacted> --- arch/x86/kernel/relocate_kernel_64.S | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index 307d3bac5f04..2ecbdcbe985b 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S@@ -200,9 +200,11 @@ identity_mapped: movq %rax, %cr3 lea PAGE_SIZE(%r8), %rsp call swap_pages - movq $virtual_mapped, %rax - pushq %rax - ret + jmp *virtual_mapped_addr(%rip) + + /* Absolute value for PIE support */ +virtual_mapped_addr: + .quad virtual_mapped virtual_mapped: movq RSP(%r8), %rsp
--
2.15.0.rc0.271.g36b669edcc-goog