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| author | Yury Norov <yury.norov@gmail.com> | 2022-09-20 16:13:12 +0300 |
|---|---|---|
| committer | Yury Norov <yury.norov@gmail.com> | 2022-09-21 02:11:44 +0300 |
| commit | 546a073d628111e3338af689938407e77d5dc38f (patch) | |
| tree | a10422c8025db39ef7540a85e61bacfe1ff400ae | |
| parent | aa47a7c215e79a2ade6916f163c5a17b561bce4f (diff) | |
| download | linux-546a073d628111e3338af689938407e77d5dc38f.tar.xz | |
powerpc/64: don't refer nr_cpu_ids in asm code when it's undefined
generic_secondary_common_init() calls LOAD_REG_ADDR(r7, nr_cpu_ids)
conditionally on CONFIG_SMP. However, if 'NR_CPUS == 1', kernel doesn't
use the nr_cpu_ids, and in C code, it's just:
#if NR_CPUS == 1
#define nr_cpu_ids
...
This series makes declaration of nr_cpu_ids conditional on NR_CPUS == 1,
and that reveals the issue, because compiler can't link the
LOAD_REG_ADDR(r7, nr_cpu_ids) against nonexisting symbol.
Current code looks unsafe for those who build kernel with CONFIG_SMP=y and
NR_CPUS == 1. This is weird configuration, but not disallowed.
Fix the linker error by replacing LOAD_REG_ADDR() with LOAD_REG_IMMEDIATE()
conditionally on NR_CPUS == 1.
As the following patch adds CONFIG_FORCE_NR_CPUS option that has the
similar effect on nr_cpu_ids, make the generic_secondary_common_init()
conditional on it too.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Yury Norov <yury.norov@gmail.com>
| -rw-r--r-- | arch/powerpc/kernel/head_64.S | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/head_64.S b/arch/powerpc/kernel/head_64.S index cf2c08902c05..d36939029701 100644 --- a/arch/powerpc/kernel/head_64.S +++ b/arch/powerpc/kernel/head_64.S @@ -400,8 +400,12 @@ generic_secondary_common_init: #else LOAD_REG_ADDR(r8, paca_ptrs) /* Load paca_ptrs pointe */ ld r8,0(r8) /* Get base vaddr of array */ +#if (NR_CPUS == 1) || defined(CONFIG_FORCE_NR_CPUS) + LOAD_REG_IMMEDIATE(r7, NR_CPUS) +#else LOAD_REG_ADDR(r7, nr_cpu_ids) /* Load nr_cpu_ids address */ lwz r7,0(r7) /* also the max paca allocated */ +#endif li r5,0 /* logical cpu id */ 1: sldi r9,r5,3 /* get paca_ptrs[] index from cpu id */ |