Pushing an immediate absolute address to the stack is not permitted when linking x86_64 code in PIE mode. Usually, the address can be taken using a RIP-relative LEA instruction, but this is not possible here as there are no available registers.
So instead, take the address into a static global, and push it onto the stack using a RIP-relative memory operand. Signed-off-by: Ard Biesheuvel <[email protected]> --- arch/x86/kernel/rethook.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/rethook.c b/arch/x86/kernel/rethook.c index 85e2f2d16a90..50812ac718b0 100644 --- a/arch/x86/kernel/rethook.c +++ b/arch/x86/kernel/rethook.c @@ -11,6 +11,10 @@ __visible void arch_rethook_trampoline_callback(struct pt_regs *regs); +#ifdef CONFIG_X86_64 +static __used void * const __arch_rethook_trampoline = &arch_rethook_trampoline; +#endif + #ifndef ANNOTATE_NOENDBR #define ANNOTATE_NOENDBR #endif @@ -27,7 +31,7 @@ asm( #ifdef CONFIG_X86_64 ANNOTATE_NOENDBR "\n" /* 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" + " pushq __arch_rethook_trampoline(%rip)\n" UNWIND_HINT_FUNC " pushq $" __stringify(__KERNEL_DS) "\n" /* Save the 'sp - 16', this will be fixed later. */ -- 2.47.3
