diff options
| author | Uros Bizjak <ubizjak@gmail.com> | 2023-12-04 22:02:29 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2023-12-11 11:47:14 +0100 |
| commit | 0e3703630bd3fead041a6bfb3a3f2a9891af6c34 (patch) | |
| tree | 610d738bf6c30b4db16044479fe23f3244781c5f /arch/x86 | |
| parent | fc50065325f8b88d6986f089ae103b5db858ab96 (diff) | |
x86/percpu: Fix "const_pcpu_hot" version generation failure
Version generation for "const_pcpu_hot" symbol failed because genksyms
doesn't know the __seg_gs keyword. Effectively revert commit 4604c052b84d
("x86/percpu: Declare const_pcpu_hot as extern const variable") and
use this_cpu_read_const() instead to avoid "sparse: dereference of
noderef expression" warning when reading const_pcpu_hot.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20231204210320.114429-1-ubizjak@gmail.com
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/current.h | 5 | ||||
| -rw-r--r-- | arch/x86/include/asm/percpu.h | 7 | ||||
| -rw-r--r-- | arch/x86/include/asm/processor.h | 2 |
3 files changed, 11 insertions, 3 deletions
diff --git a/arch/x86/include/asm/current.h b/arch/x86/include/asm/current.h index 9fbd7cb2dc86..c8c5674d69f6 100644 --- a/arch/x86/include/asm/current.h +++ b/arch/x86/include/asm/current.h @@ -37,12 +37,13 @@ static_assert(sizeof(struct pcpu_hot) == 64); DECLARE_PER_CPU_ALIGNED(struct pcpu_hot, pcpu_hot); /* const-qualified alias to pcpu_hot, aliased by linker. */ -extern const struct pcpu_hot __percpu_seg_override const_pcpu_hot; +DECLARE_PER_CPU_ALIGNED(const struct pcpu_hot __percpu_seg_override, + const_pcpu_hot); static __always_inline struct task_struct *get_current(void) { if (IS_ENABLED(CONFIG_USE_X86_SEG_SUPPORT)) - return const_pcpu_hot.current_task; + return this_cpu_read_const(const_pcpu_hot.current_task); return this_cpu_read_stable(pcpu_hot.current_task); } diff --git a/arch/x86/include/asm/percpu.h b/arch/x86/include/asm/percpu.h index 0f12b2004b94..3859abad19ec 100644 --- a/arch/x86/include/asm/percpu.h +++ b/arch/x86/include/asm/percpu.h @@ -28,6 +28,7 @@ #else /* ...!ASSEMBLY */ +#include <linux/build_bug.h> #include <linux/kernel.h> #include <linux/stringify.h> @@ -462,6 +463,7 @@ do { \ #define this_cpu_write_8(pcp, val) __raw_cpu_write(volatile, pcp, val) #endif +#define this_cpu_read_const(pcp) __raw_cpu_read(, pcp) #else /* CONFIG_USE_X86_SEG_SUPPORT */ #define raw_cpu_read_1(pcp) percpu_from_op(1, , "mov", pcp) @@ -486,6 +488,11 @@ do { \ #define this_cpu_write_8(pcp, val) percpu_to_op(8, volatile, "mov", (pcp), val) #endif +/* + * The generic per-cpu infrastrucutre is not suitable for + * reading const-qualified variables. + */ +#define this_cpu_read_const(pcp) ({ BUILD_BUG(); (typeof(pcp))0; }) #endif /* CONFIG_USE_X86_SEG_SUPPORT */ #define raw_cpu_add_1(pcp, val) percpu_add_op(1, , (pcp), val) diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index f20e87632669..a94a857152c4 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -519,7 +519,7 @@ static __always_inline unsigned long current_top_of_stack(void) * entry trampoline. */ if (IS_ENABLED(CONFIG_USE_X86_SEG_SUPPORT)) - return const_pcpu_hot.top_of_stack; + return this_cpu_read_const(const_pcpu_hot.top_of_stack); return this_cpu_read_stable(pcpu_hot.top_of_stack); } |