From 6de6066c0d24a66df465cf87a4041ef7ef35ba6f Mon Sep 17 00:00:00 2001 From: Yuriy Kolerov Date: Wed, 12 Aug 2015 17:23:32 +0300 Subject: [PATCH] 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: Yuriy Kolerov Signed-off-by: Vineet Gupta --- arch/arc/include/asm/futex.h | 6 +++--- arch/arc/kernel/entry.S | 6 +++--- arch/arc/kernel/unaligned.c | 6 +++--- 3 files changed, 9 insertions(+), 9 deletions(-) diff --git a/arch/arc/include/asm/futex.h b/arch/arc/include/asm/futex.h index 8f449982523b..11e1b1f3acda 100644 --- a/arch/arc/include/asm/futex.h +++ b/arch/arc/include/asm/futex.h @@ -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" diff --git a/arch/arc/kernel/entry.S b/arch/arc/kernel/entry.S index f7a82fd4d601..589abf5172d6 100644 --- a/arch/arc/kernel/entry.S +++ b/arch/arc/kernel/entry.S @@ -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 diff --git a/arch/arc/kernel/unaligned.c b/arch/arc/kernel/unaligned.c index 74db59b6f392..abd961f3e763 100644 --- a/arch/arc/kernel/unaligned.c +++ b/arch/arc/kernel/unaligned.c @@ -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" \ -- 2.20.1