[lld] [PAC][lld] Fix reloc against adrp imm in PAC PLT header (PR #113429)

[Daniil Kovalev via llvm-commits]

https://github.com/kovdan01 created https://github.com/llvm/llvm-project/pull/113429

The PAC PLT header contains adrp instruction which immediate should be filled. In https://reviews.llvm.org/D62609, the adrp instruction address was calculated incorrectly. This patch resolves the issue.

The test is already present in test/ELF/aarch64-feature-pac.s

>From f63b3222f7eb91f4492af2752802979691954821 Mon Sep 17 00:00:00 2001
From: Daniil Kovalev <dkovalev at accesssoftek.com>
Date: Mon, 21 Oct 2024 16:11:27 +0300
Subject: [PATCH] [PAC][lld] Fix reloc against adrp imm in PAC PLT header

The PAC PLT header contains adrp instruction which immediate should be
filled. In https://reviews.llvm.org/D62609, the adrp instruction address
was calculated incorrectly. This patch resolves the issue.

The test is already present in test/ELF/aarch64-feature-pac.s
---
 lld/ELF/Arch/AArch64.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lld/ELF/Arch/AArch64.cpp b/lld/ELF/Arch/AArch64.cpp
index f4f867d019136e..28e0fce6a6f499 100644
--- a/lld/ELF/Arch/AArch64.cpp
+++ b/lld/ELF/Arch/AArch64.cpp
@@ -1048,7 +1048,7 @@ void AArch64BtiPac::writePltHeader(uint8_t *buf) const {
   memcpy(buf, pltData, sizeof(pltData));
 
   relocateNoSym(buf + 4, R_AARCH64_ADR_PREL_PG_HI21,
-                getAArch64Page(got + 16) - getAArch64Page(plt + 8));
+                getAArch64Page(got + 16) - getAArch64Page(plt + 4));
   relocateNoSym(buf + 8, R_AARCH64_LDST64_ABS_LO12_NC, got + 16);
   relocateNoSym(buf + 12, R_AARCH64_ADD_ABS_LO12_NC, got + 16);
   if (!btiHeader)