[PATCH v2 05/27] x86: relocate_kernel - Adapt assembly for PIE support
From: Thomas Garnier <hidden>
Date: 2018-03-13 20:59:23
Also in:
kvm, linux-arch, linux-crypto, lkml, xen-devel
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 11eda21eb697..a7227dfe1a2b 100644
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S@@ -208,9 +208,11 @@ 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
--
2.16.2.660.g709887971b-goog
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