[PATCH] ARM: entry: add .ltorg directive to keep literals in range

[Ard Biesheuvel]

LKP reports a build issue on Clang, related to a literal load of
__current issued through the ldr_va macro. This turns out to be due to
the fact that group relocations are disabled when CONFIG_COMPILE_TEST=y,
which means that the ldr_va macro resolves to a pair of LDR
instructions, the first one being a literal load issued too far from its
literal pool.

Due to the introduction of a couple of new uses of this macro in commit
508074607c7b95b2 ("ARM: 9195/1: entry: avoid explicit literal loads"),
the literal pools end up getting rearranged in a way that causes the
literal for __current to go out of range. Let's fix this up by putting a
.ltorg directive in a suitable place in the code.

Cc: Nathan Chancellor <nathan at kernel.org>
Cc: Nick Desaulniers <ndesaulniers at google.com>
Fixes: 508074607c7b95b2 ("ARM: 9195/1: entry: avoid explicit literal loads")
Reported-by: kernel test robot <lkp at intel.com>
Link: https://lore.kernel.org/all/202205290805.1vZLAr36-lkp@intel.com/
Signed-off-by: Ard Biesheuvel <ardb at kernel.org>
---
 arch/arm/kernel/entry-common.S | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 7aa3ded4af92..6a447ac67d80 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -298,14 +298,15 @@ local_restart:
 9001:
 	sub	lr, saved_pc, #4
 	str	lr, [sp, #S_PC]
 	get_thread_info tsk
 	b	ret_fast_syscall
 #endif
 ENDPROC(vector_swi)
+	.ltorg
 
 	/*
 	 * This is the really slow path.  We're going to be doing
 	 * context switches, and waiting for our parent to respond.
 	 */
 __sys_trace:
 	add	r0, sp, #S_OFF
-- 
2.30.2