Commit 6de6066c authored by Yuriy Kolerov's avatar Yuriy Kolerov Committed by Vineet Gupta
Browse files

ARC: change some branchs to jumps to resolve linkage errors 



When kernel's binary becomes large enough (32M and more) errors
may occur during the final linkage stage. It happens because
the build system uses short relocations for ARC  by default.
This problem may be easily resolved by passing -mlong-calls
option to GCC to use long absolute jumps (j) instead of short
relative branchs (b).

But there are fragments of pure assembler code exist which use
branchs in inappropriate places and cause a linkage error because
of relocations overflow.

First of these fragments is .fixup insertion in futex.h and
unaligned.c. It inserts a code in the separate section (.fixup)
with branch instruction. It leads to the linkage error when
kernel becomes large.

Second of these fragments is calling scheduler's functions
(common kernel code) from entry.S of ARC's code. When kernel's
binary becomes large it may lead to the linkage error because
scheduler may occur far enough from ARC's code in the final
binary.

Signed-off-by: default avatarYuriy Kolerov <yuriy.kolerov@synopsys.com>
Signed-off-by: default avatarVineet Gupta <vgupta@synopsys.com>
parent eb2cd8b7

arch/arc/include/asm/futex.h

+3 −3
Original line number Diff line number Diff line
@@ -31,7 +31,7 @@ 
	"	.section .fixup,\"ax\"		\n"	\

	"	.align  4			\n"	\

	"4:	mov %0, %4			\n"	\

	"	b   3b				\n"	\

	"	j   3b				\n"	\

	"	.previous			\n"	\

	"	.section __ex_table,\"a\"	\n"	\

	"	.align  4			\n"	\
@@ -58,7 +58,7 @@ 
	"	.section .fixup,\"ax\"		\n"	\

	"	.align  4			\n"	\

	"4:	mov %0, %4			\n"	\

	"	b   3b				\n"	\

	"	j   3b				\n"	\

	"	.previous			\n"	\

	"	.section __ex_table,\"a\"	\n"	\

	"	.align  4			\n"	\
@@ -178,7 +178,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, u32 expval, 
	"3:	\n"

	"	.section .fixup,\"ax\"	\n"

	"4:	mov %0, %5	\n"

	"	b   3b	\n"

	"	j   3b	\n"

	"	.previous	\n"

	"	.section __ex_table,\"a\"	\n"

	"	.align  4	\n"

arch/arc/kernel/entry.S

+3 −3
Original line number Diff line number Diff line
@@ -42,7 +42,7 @@ ENTRY(ret_from_fork) 
	; when the forked child comes here from the __switch_to function

	; r0 has the last task pointer.

	; put last task in scheduler queue

	bl   @schedule_tail

	jl   @schedule_tail



	ld   r9, [sp, PT_status32]

	brne r9, 0, 1f
@@ -320,7 +320,7 @@ resume_user_mode_begin: 
	; --- (Slow Path #1) task preemption ---

	bbit0  r9, TIF_NEED_RESCHED, .Lchk_pend_signals

	mov    blink, resume_user_mode_begin  ; tail-call to U mode ret chks

	b      @schedule 	; BTST+Bnz causes relo error in link

	j      @schedule 	; BTST+Bnz causes relo error in link



.Lchk_pend_signals:

	IRQ_ENABLE	r10
@@ -381,7 +381,7 @@ resume_kernel_mode: 
	bbit0  r9, TIF_NEED_RESCHED, .Lrestore_regs



	; Invoke PREEMPTION

	bl      preempt_schedule_irq

	jl      preempt_schedule_irq



	; preempt_schedule_irq() always returns with IRQ disabled

#endif

arch/arc/kernel/unaligned.c

+3 −3
Original line number Diff line number Diff line
@@ -34,7 +34,7 @@ 
	"	.section .fixup,\"ax\"\n"		\

	"	.align	4\n"				\

	"3:	mov	%0, 1\n"			\

	"	b	2b\n"				\

	"	j	2b\n"				\

	"	.previous\n"				\

	"	.section __ex_table,\"a\"\n"		\

	"	.align	4\n"				\
@@ -82,7 +82,7 @@ 
		"	.section .fixup,\"ax\"\n"	\

		"	.align	4\n"			\

		"4:	mov	%0, 1\n"		\

		"	b	3b\n"			\

		"	j	3b\n"			\

		"	.previous\n"			\

		"	.section __ex_table,\"a\"\n"	\

		"	.align	4\n"			\
@@ -113,7 +113,7 @@ 
		"	.section .fixup,\"ax\"\n"	\

		"	.align	4\n"			\

		"6:	mov	%0, 1\n"		\

		"	b	5b\n"			\

		"	j	5b\n"			\

		"	.previous\n"			\

		"	.section __ex_table,\"a\"\n"	\

		"	.align	4\n"			\

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