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[RFC,14/28] x86/rethook: Use RIP-relative reference for return address

Message ID 20240925150059.3955569-44-ardb+git@google.com
State New
Headers show
Series x86: Rely on toolchain for relocatable code | expand

Commit Message

Ard Biesheuvel Sept. 25, 2024, 3:01 p.m. UTC 
From: Ard Biesheuvel <ardb@kernel.org>

Instead of pushing an immediate absolute address, which is incompatible
with PIE codegen or linking, use a LEA instruction to take the address
into a register.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/x86/kernel/rethook.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
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Patch

diff --git a/arch/x86/kernel/rethook.c b/arch/x86/kernel/rethook.c
index 8a1c0111ae79..3b3c17ba3cd5 100644
--- a/arch/x86/kernel/rethook.c
+++ b/arch/x86/kernel/rethook.c
@@ -27,7 +27,8 @@  asm(
 #ifdef CONFIG_X86_64
 	ANNOTATE_NOENDBR	/* This is only jumped from ret instruction */
 	/* Push a fake return address to tell the unwinder it's a rethook. */
-	"	pushq $arch_rethook_trampoline\n"
+	"	leaq arch_rethook_trampoline(%rip), %rdi\n"
+	"	pushq %rdi\n"
 	UNWIND_HINT_FUNC
 	"       pushq $" __stringify(__KERNEL_DS) "\n"
 	/* Save the 'sp - 16', this will be fixed later. */