X-Git-Url: http://git.cascardo.info/?a=blobdiff_plain;f=arch%2Farm64%2Fkernel%2Falternative.c;fp=arch%2Farm64%2Fkernel%2Falternative.c;h=06d650f61da716a8e318a802b7af41ab9087bfaa;hb=c831b2ae257853ecd36ea4f7d788bf0665e4cf89;hp=992918dfbe2db6a64ba01b08df86db8f203640ac;hpb=46084bc253e1acdd6c47846e91fc20f4ab4f1fec;p=cascardo%2Flinux.git

diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
index 992918dfbe2d..06d650f61da7 100644
--- a/arch/arm64/kernel/alternative.c
+++ b/arch/arm64/kernel/alternative.c
@@ -58,6 +58,8 @@ static bool branch_insn_requires_update(struct alt_instr *alt, unsigned long pc)
 	BUG();
 }
 
+#define align_down(x, a)	((unsigned long)(x) & ~(((unsigned long)(a)) - 1))
+
 static u32 get_alt_insn(struct alt_instr *alt, u32 *insnptr, u32 *altinsnptr)
 {
 	u32 insn;
@@ -79,6 +81,19 @@ static u32 get_alt_insn(struct alt_instr *alt, u32 *insnptr, u32 *altinsnptr)
 			offset = target - (unsigned long)insnptr;
 			insn = aarch64_set_branch_offset(insn, offset);
 		}
+	} else if (aarch64_insn_is_adrp(insn)) {
+		s32 orig_offset, new_offset;
+		unsigned long target;
+
+		/*
+		 * If we're replacing an adrp instruction, which uses PC-relative
+		 * immediate addressing, adjust the offset to reflect the new
+		 * PC. adrp operates on 4K aligned addresses.
+		 */
+		orig_offset  = aarch64_insn_adrp_get_offset(insn);
+		target = align_down(altinsnptr, SZ_4K) + orig_offset;
+		new_offset = target - align_down(insnptr, SZ_4K);
+		insn = aarch64_insn_adrp_set_offset(insn, new_offset);
 	} else if (aarch64_insn_uses_literal(insn)) {
 		/*
 		 * Disallow patching unhandled instructions using PC relative