| Message ID | 20200608085731.1405854-1-maz@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: arm64: Stop sparse from moaning at __hyp_this_cpu_ptr | expand |
On Mon, Jun 08, 2020 at 09:57:31AM +0100, Marc Zyngier wrote: > Sparse complains that __hyp_this_cpu_ptr() returns something > that is flagged noderef and not in the correct address space > (both being the result of the __percpu annotation). > > Pretend that __hyp_this_cpu_ptr() knows what it is doing by > forcefully casting the pointer with __kernel __force. > > Signed-off-by: Marc Zyngier <maz@kernel.org> > --- > arch/arm64/include/asm/kvm_asm.h | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h > index 0c9b5fc4ba0a..82691406d493 100644 > --- a/arch/arm64/include/asm/kvm_asm.h > +++ b/arch/arm64/include/asm/kvm_asm.h > @@ -81,12 +81,17 @@ extern u32 __kvm_get_mdcr_el2(void); > > extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ]; > > -/* Home-grown __this_cpu_{ptr,read} variants that always work at HYP */ > +/* > + * Home-grown __this_cpu_{ptr,read} variants that always work at HYP, > + * provided that sym is really a *symbol* and not a pointer obtained from Look at `this_cpu_ptr` one thing that stood out was `__verify_pcpu_ptr` that is documented to be suitable for used in custom per CPU macros. I didn't get how it worked (a type check?) but maybe it would work here to validate the argment was indeed a per CPU symbol? > + * a data structure. As for SHIFT_PERCPU_PTR(), the creative casting keeps > + * sparse quiet. > + */ > #define __hyp_this_cpu_ptr(sym) \ > ({ \ > void *__ptr = hyp_symbol_addr(sym); \ > __ptr += read_sysreg(tpidr_el2); \ > - (typeof(&sym))__ptr; \ > + (typeof(sym) __kernel __force *)__ptr; \ > }) > > #define __hyp_this_cpu_read(sym) \
On 2020-06-08 16:00, Andrew Scull wrote: > On Mon, Jun 08, 2020 at 09:57:31AM +0100, Marc Zyngier wrote: >> Sparse complains that __hyp_this_cpu_ptr() returns something >> that is flagged noderef and not in the correct address space >> (both being the result of the __percpu annotation). >> >> Pretend that __hyp_this_cpu_ptr() knows what it is doing by >> forcefully casting the pointer with __kernel __force. >> >> Signed-off-by: Marc Zyngier <maz@kernel.org> >> --- >> arch/arm64/include/asm/kvm_asm.h | 9 +++++++-- >> 1 file changed, 7 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/include/asm/kvm_asm.h >> b/arch/arm64/include/asm/kvm_asm.h >> index 0c9b5fc4ba0a..82691406d493 100644 >> --- a/arch/arm64/include/asm/kvm_asm.h >> +++ b/arch/arm64/include/asm/kvm_asm.h >> @@ -81,12 +81,17 @@ extern u32 __kvm_get_mdcr_el2(void); >> >> extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ]; >> >> -/* Home-grown __this_cpu_{ptr,read} variants that always work at HYP >> */ >> +/* >> + * Home-grown __this_cpu_{ptr,read} variants that always work at HYP, >> + * provided that sym is really a *symbol* and not a pointer obtained >> from > > Look at `this_cpu_ptr` one thing that stood out was `__verify_pcpu_ptr` > that is documented to be suitable for used in custom per CPU macros. I > didn't get how it worked (a type check?) but maybe it would work here > to validate the argment was indeed a per CPU symbol? It only works for sparse, but that is definitely a good addition while we're fixing the sparse compliance. Thanks, M.
diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h index 0c9b5fc4ba0a..82691406d493 100644 --- a/arch/arm64/include/asm/kvm_asm.h +++ b/arch/arm64/include/asm/kvm_asm.h @@ -81,12 +81,17 @@ extern u32 __kvm_get_mdcr_el2(void); extern char __smccc_workaround_1_smc[__SMCCC_WORKAROUND_1_SMC_SZ]; -/* Home-grown __this_cpu_{ptr,read} variants that always work at HYP */ +/* + * Home-grown __this_cpu_{ptr,read} variants that always work at HYP, + * provided that sym is really a *symbol* and not a pointer obtained from + * a data structure. As for SHIFT_PERCPU_PTR(), the creative casting keeps + * sparse quiet. + */ #define __hyp_this_cpu_ptr(sym) \ ({ \ void *__ptr = hyp_symbol_addr(sym); \ __ptr += read_sysreg(tpidr_el2); \ - (typeof(&sym))__ptr; \ + (typeof(sym) __kernel __force *)__ptr; \ }) #define __hyp_this_cpu_read(sym) \
Sparse complains that __hyp_this_cpu_ptr() returns something that is flagged noderef and not in the correct address space (both being the result of the __percpu annotation). Pretend that __hyp_this_cpu_ptr() knows what it is doing by forcefully casting the pointer with __kernel __force. Signed-off-by: Marc Zyngier <maz@kernel.org> --- arch/arm64/include/asm/kvm_asm.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-)