From: Yury Norov Date: Tue, 20 Sep 2022 13:13:12 +0000 (-0700) Subject: powerpc/64: don't refer nr_cpu_ids in asm code when it's undefined X-Git-Tag: v6.1-rc1~82^2~22 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=546a073d628111e3338af689938407e77d5dc38f;p=linux-block.git 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 Signed-off-by: Yury Norov --- 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 */