Messages in this thread | | | Subject | Re: [PATCH -next] powerpc/book3s64: fix link error with CONFIG_PPC_RADIX_MMU=n | From | Christophe Leroy <> | Date | Mon, 7 Sep 2020 10:11:01 +0200 |
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Le 07/09/2020 à 03:51, Yang Yingliang a écrit : > > On 2020/9/6 14:50, Christophe Leroy wrote: >> >> >> Le 05/09/2020 à 13:25, Yang Yingliang a écrit : >>> Fix link error when CONFIG_PPC_RADIX_MMU is disabled: >>> powerpc64-linux-gnu-ld: >>> arch/powerpc/platforms/pseries/lpar.o:(.toc+0x0): undefined reference >>> to `mmu_pid_bits' >>> >>> Reported-by: Hulk Robot <hulkci@huawei.com> >>> Signed-off-by: Yang Yingliang <yangyingliang@huawei.com> >>> --- >>> arch/powerpc/mm/book3s64/mmu_context.c | 4 ++++ >> >> In your commit log, you are just mentionning >> arch/powerpc/platforms/pseries/lpar.o, which is right. >> >> You shouldn't need to modify arch/powerpc/mm/book3s64/mmu_context.c at >> all, see below. >> >>> arch/powerpc/platforms/pseries/lpar.c | 2 ++ >>> 2 files changed, 6 insertions(+) >>> >>> diff --git a/arch/powerpc/mm/book3s64/mmu_context.c >>> b/arch/powerpc/mm/book3s64/mmu_context.c >>> index 0ba30b8b935b..a8e292cd88f0 100644 >>> --- a/arch/powerpc/mm/book3s64/mmu_context.c >>> +++ b/arch/powerpc/mm/book3s64/mmu_context.c >>> @@ -152,6 +152,7 @@ void hash__setup_new_exec(void) >>> static int radix__init_new_context(struct mm_struct *mm) >>> { >>> +#ifdef CONFIG_PPC_RADIX_MMU >> >> This shouldn't be required. radix__init_new_context() is only called >> when radix_enabled() returns true. >> As it is a static function, when it is not called it gets optimised >> away, so you will never get an undefined reference to `mmu_pid_bits` >> there. > powerpc64-linux-gnu-ld: > arch/powerpc/mm/book3s64/mmu_context.o:(.toc+0x0): undefined reference > to `mmu_pid_bits' > powerpc64-linux-gnu-ld: > arch/powerpc/mm/book3s64/mmu_context.o:(.toc+0x8): undefined reference > to `mmu_base_pid' > > > mmu_context.c is always compiled, it uses mmu_pid_bits and mmu_base_pid.
Yes, mmu_context.c is always compiled, but as I explained, radix__init_new_context() is defined as 'static' so it is optimised out when radix_enabled() returns false because there is no caller in that case.
I just made the test with ppc64_defconfig + CONFIG_PPC_RADIX_MMU=n (GCC 8.1)
The only failure I got was on lpar.c, which I fixed by enclosing the entire radix_init_pseries() in an #ifdef.
Once this is fixed, the build is OK, without any modification to mmu_context.c
powerpc64-linux-objdump -x arch/powerpc/mm/book3s64/mmu_context.o shows only the following objects in the .toc:
RELOCATION RECORDS FOR [.toc]: OFFSET TYPE VALUE 0000000000000000 R_PPC64_ADDR64 kmalloc_caches 0000000000000008 R_PPC64_ADDR64 vmemmap 0000000000000010 R_PPC64_ADDR64 __pmd_frag_nr 0000000000000018 R_PPC64_ADDR64 __pmd_frag_size_shift
mmu_pid_bits and mmu_base_pid are not part of the undefined objetcs:
0000000000000000 *UND* 0000000000000000 vmemmap 0000000000000000 *UND* 0000000000000000 .mm_iommu_init 0000000000000000 *UND* 0000000000000000 __pmd_frag_nr 0000000000000000 *UND* 0000000000000000 .ida_alloc_range 0000000000000000 *UND* 0000000000000000 .slb_setup_new_exec 0000000000000000 *UND* 0000000000000000 mmu_feature_keys 0000000000000000 *UND* 0000000000000000 .memset 0000000000000000 *UND* 0000000000000000 .memcpy 0000000000000000 *UND* 0000000000000000 .slice_init_new_context_exec 0000000000000000 *UND* 0000000000000000 ._mcount 0000000000000000 *UND* 0000000000000000 .__free_pages 0000000000000000 *UND* 0000000000000000 __pmd_frag_size_shift 0000000000000000 *UND* 0000000000000000 .slice_setup_new_exec 0000000000000000 *UND* 0000000000000000 .ida_free 0000000000000000 *UND* 0000000000000000 .pte_frag_destroy 0000000000000000 *UND* 0000000000000000 .kfree 0000000000000000 *UND* 0000000000000000 .pkey_mm_init 0000000000000000 *UND* 0000000000000000 .kmem_cache_alloc_trace 0000000000000000 *UND* 0000000000000000 .__warn_printk 0000000000000000 *UND* 0000000000000000 _mcount 0000000000000000 *UND* 0000000000000000 kmalloc_caches
Christophe
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