Enable strict percpu address space checks via x86 named address space qualifiers. Percpu variables are declared in __seg_gs/__seg_fs named AS and kept named AS qualified until they are dereferenced via percpu accessor. This approach enables various compiler checks for cross-namespace variable assignments. Please note that current version of sparse doesn't know anything about __typeof_unqual__() operator. Avoid the usage of __typeof_unqual__() when sparse checking is active to prevent sparse errors with unknowing keyword. The proposed patch by Dan Carpenter to implement __typeof_unqual__() handling in sparse is located at: https://lore.kernel.org/lkml/5b8d0dee-8fb6-45af-ba6c-7f74aff9a4b8@stanley.mountain/ v2: - Add comment to remove test for __CHECKER__ once sparse learns about __typeof_unqual__. - Add Acked-by: tags. v3: - Rename __per_cpu_qual to __percpu_qual. - Add more Acked-by: tags. Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Dennis Zhou <dennis@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Andy Lutomirski <luto@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Nadav Amit <nadav.amit@xxxxxxxxx> Cc: Brian Gerst <brgerst@xxxxxxxxx> Cc: Dan Carpenter <dan.carpenter@xxxxxxxxxx> Cc: H. Peter Anvin <hpa@xxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Uros Bizjak (6): x86/kgdb: Use IS_ERR_PCPU() macro compiler.h: Introduce TYPEOF_UNQUAL() macro percpu: Use TYPEOF_UNQUAL() in variable declarations percpu: Use TYPEOF_UNQUAL() in *_cpu_ptr() accessors percpu: Repurpose __percpu tag as a named address space qualifier percpu/x86: Enable strict percpu checks via named AS qualifiers arch/x86/include/asm/percpu.h | 38 ++++++++++++++++++++++++--------- arch/x86/kernel/kgdb.c | 2 +- fs/bcachefs/util.h | 2 +- include/asm-generic/percpu.h | 39 ++++++++++++++++++++++------------ include/linux/compiler.h | 13 ++++++++++++ include/linux/compiler_types.h | 2 +- include/linux/part_stat.h | 2 +- include/linux/percpu-defs.h | 6 +++--- include/net/snmp.h | 5 ++--- init/Kconfig | 3 +++ kernel/locking/percpu-rwsem.c | 2 +- net/mpls/internal.h | 4 ++-- 12 files changed, 82 insertions(+), 36 deletions(-) -- 2.42.0
