Subject: Re: [PATCH] powerpc: Revert removing of _INIT_GLOBAL(), _STATIC() and _INIT_STATIC()

From: Benjamin Herrenschmidt <[email-masked]>
Date: Tue, 15 Jul 2014 12:05:55 +1000

On Mon, 2014-07-14 at 20:12 -0400, Steven Rostedt wrote:
> I wanted to test some new ftrace code on my PASemi electra powerpc box.
> But unfortunately it failed to build. It failed with this:
> 
>   LD      init/built-in.o
> arch/powerpc/kernel/head_64.o:arch/powerpc/kernel/exceptions-64s.S:874:
>   relocation truncated to fit: R_PPC64_REL14 against `.text'+1c90
> Makefile:864: recipe for target 'vmlinux' failed

Weird ... what are your gcc and binutils versions ? Smells like a
toolchain issue to me but I need to dig a bit more. Doesn't hit any
of my test configs here.

Cheers,
Ben.

> Bisecting it lead me down to this commit:
> 
> commit 6a3bab90cf78bc579638525cb76ac240f8253803
> Author: Anton Blanchard <[email-masked]>
> Date:   Tue Feb 4 16:06:11 2014 +1100
> 
>     powerpc: Remove some unnecessary uses of _GLOBAL() and _STATIC()
>     
>     There is no need to create a function descriptor for functions
>     called locally out of assembly.
> 
> 
> And by reverting this and:
> 
> commit a0e971ffb9d9dae3b9892fb548bd2497db758f60
> Author: Anton Blanchard <[email-masked]>
> Date:   Tue Feb 4 16:06:25 2014 +1100
> 
>     powerpc: Remove _INIT_GLOBAL(), _STATIC() and _INIT_STATIC()
>     
>     Now there are no users of _INIT_GLOBAL(), _STATIC() and
>     _INIT_STATIC() we can remove them.
> 
> My box builds and boots again.
> 
> Signed-off-by: Steven Rostedt <[email-masked]>
> ---
> diff --git a/arch/powerpc/include/asm/ppc_asm.h b/arch/powerpc/include/asm/ppc_asm.h
> index 9ea266e..1baf197 100644
> --- a/arch/powerpc/include/asm/ppc_asm.h
> +++ b/arch/powerpc/include/asm/ppc_asm.h
> @@ -217,6 +217,20 @@ name: \
>  	addi r2,r2,(.TOC.-0b)@l; \
>  	.localentry name,.-name
>  
> +#define _INIT_GLOBAL(name) \
> +	__REF; \
> +	.align 2 ; \
> +	.globl name; \
> +	.globl GLUE(.,name); \
> +	.section ".opd","aw"; \
> +name: \
> +	.quad GLUE(.,name); \
> +	.quad .TOC.@tocbase; \
> +	.quad 0; \
> +	.previous; \
> +	.type GLUE(.,name),@function; \
> +GLUE(.,name):
> +
>  #define _KPROBE(name) \
>  	.section ".kprobes.text","a"; \
>  	.align 2 ; \
> @@ -265,6 +279,30 @@ GLUE(.,name):
>  
>  #endif
>  
> +#define _STATIC(name) \
> +	.section ".text"; \
> +	.align 2 ; \
> +	.section ".opd","aw"; \
> +name: \
> +	.quad GLUE(.,name); \
> +	.quad .TOC.@tocbase; \
> +	.quad 0; \
> +	.previous; \
> +	.type GLUE(.,name),@function; \
> +GLUE(.,name):
> +
> +#define _INIT_STATIC(name) \
> +	__REF; \
> +	.align 2 ; \
> +	.section ".opd","aw"; \
> +name: \
> +	.quad GLUE(.,name); \
> +	.quad .TOC.@tocbase; \
> +	.quad 0; \
> +	.previous; \
> +	.type GLUE(.,name),@function; \
> +GLUE(.,name):
> +
>  #else /* 32-bit */
>  
>  #define _ENTRY(n)	\
> diff --git a/arch/powerpc/kernel/exceptions-64e.S b/arch/powerpc/kernel/exceptions-64e.S
> index bb9cac6..ce0c55d 100644
> --- a/arch/powerpc/kernel/exceptions-64e.S
> +++ b/arch/powerpc/kernel/exceptions-64e.S
> @@ -1580,14 +1580,14 @@ _GLOBAL(book3e_secondary_thread_init)
>  	mflr	r28
>  	b	3b
>  
> -init_core_book3e:
> +_STATIC(init_core_book3e)
>  	/* Establish the interrupt vector base */
>  	LOAD_REG_IMMEDIATE(r3, interrupt_base_book3e)
>  	mtspr	SPRN_IVPR,r3
>  	sync
>  	blr
>  
> -init_thread_book3e:
> +_STATIC(init_thread_book3e)
>  	lis	r3,(SPRN_EPCR_ICM | SPRN_EPCR_GICM)@h
>  	mtspr	SPRN_EPCR,r3
>  
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index a7d36b1..220c5a9 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -1586,7 +1586,7 @@ power4_fixup_nap:
>   * Hash table stuff
>   */
>  	.align	7
> -do_hash_page:
> +_STATIC(do_hash_page)
>  	std	r3,_DAR(r1)
>  	std	r4,_DSISR(r1)
>  
> diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S
> index a95145d..b8986af 100644
> --- a/arch/powerpc/kernel/head_64.S
> +++ b/arch/powerpc/kernel/head_64.S
> @@ -299,7 +299,7 @@ generic_secondary_common_init:
>   * Assumes we're mapped EA == RA if the MMU is on.
>   */
>  #ifdef CONFIG_PPC_BOOK3S
> -__mmu_off:
> +_STATIC(__mmu_off)
>  	mfmsr	r3
>  	andi.	r0,r3,MSR_IR|MSR_DR
>  	beqlr
> @@ -324,7 +324,7 @@ __mmu_off:
>   *                 DT block, r4 is a physical pointer to the kernel itself
>   *
>   */
> -__start_initialization_multiplatform:
> +_GLOBAL(__start_initialization_multiplatform)
>  	/* Make sure we are running in 64 bits mode */
>  	bl	enable_64b_mode
>  
> @@ -376,7 +376,7 @@ __start_initialization_multiplatform:
>  	b	__after_prom_start
>  #endif /* CONFIG_PPC_BOOK3E */
>  
> -__boot_from_prom:
> +_INIT_STATIC(__boot_from_prom)
>  #ifdef CONFIG_PPC_OF_BOOT_TRAMPOLINE
>  	/* Save parameters */
>  	mr	r31,r3
> @@ -414,7 +414,7 @@ __boot_from_prom:
>  	 * from OF while CONFIG_PPC_OF_BOOT_TRAMPOLINE isn't selected */
>  	trap
>  
> -__after_prom_start:
> +_STATIC(__after_prom_start)
>  #ifdef CONFIG_RELOCATABLE
>  	/* process relocations for the final address of the kernel */
>  	lis	r25,PAGE_OFFSET@highest	/* compute virtual base of kernel */
> @@ -674,7 +674,7 @@ _GLOBAL(start_secondary_resume)
>  /*
>   * This subroutine clobbers r11 and r12
>   */
> -enable_64b_mode:
> +_GLOBAL(enable_64b_mode)
>  	mfmsr	r11			/* grab the current MSR */
>  #ifdef CONFIG_PPC_BOOK3E
>  	oris	r11,r11,0x8000		/* CM bit set, we'll set ICM later */
> @@ -715,7 +715,7 @@ p_toc:	.llong	__toc_start + 0x8000 - 0b
>  /*
>   * This is where the main kernel code starts.
>   */
> -start_here_multiplatform:
> +_INIT_STATIC(start_here_multiplatform)
>  	/* set up the TOC */
>  	bl      relative_toc
>  	tovirt(r2,r2)