[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging] xen/arm: atomic: Allow read_atomic() to be used in more cases
commit 9efda0281b29ac8ac5793457b8f71e6ff35f898c Author: Julien Grall <jgrall@xxxxxxxxxx> AuthorDate: Sat May 2 15:06:22 2020 +0100 Commit: Julien Grall <jgrall@xxxxxxxxxx> CommitDate: Mon May 11 10:47:57 2020 +0100 xen/arm: atomic: Allow read_atomic() to be used in more cases The current implementation of read_atomic() on Arm will not allow to: 1) Read a value from a pointer to const because the temporary variable will be const and therefore it is not possible to assign any value. This can be solved by using a union between the type and a char[0]. 2) Read a pointer value (e.g void *) because the switch contains cast from other type than the size of a pointer. This can be solved by by introducing a static inline for the switch and use void * for the pointer. Reported-by: Juergen Gross <jgross@xxxxxxxx> Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx> Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx> --- xen/include/asm-arm/atomic.h | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) diff --git a/xen/include/asm-arm/atomic.h b/xen/include/asm-arm/atomic.h index e81bf80e30..3c3d6bb04e 100644 --- a/xen/include/asm-arm/atomic.h +++ b/xen/include/asm-arm/atomic.h @@ -71,18 +71,37 @@ build_add_sized(add_u32_sized, "", WORD, uint32_t) #undef build_atomic_write #undef build_add_sized +void __bad_atomic_read(const volatile void *p, void *res); void __bad_atomic_size(void); +static always_inline void read_atomic_size(const volatile void *p, + void *res, + unsigned int size) +{ + switch ( size ) + { + case 1: + *(uint8_t *)res = read_u8_atomic(p); + break; + case 2: + *(uint16_t *)res = read_u16_atomic(p); + break; + case 4: + *(uint32_t *)res = read_u32_atomic(p); + break; + case 8: + *(uint64_t *)res = read_u64_atomic(p); + break; + default: + __bad_atomic_read(p, res); + break; + } +} + #define read_atomic(p) ({ \ - typeof(*p) __x; \ - switch ( sizeof(*p) ) { \ - case 1: __x = (typeof(*p))read_u8_atomic((uint8_t *)p); break; \ - case 2: __x = (typeof(*p))read_u16_atomic((uint16_t *)p); break; \ - case 4: __x = (typeof(*p))read_u32_atomic((uint32_t *)p); break; \ - case 8: __x = (typeof(*p))read_u64_atomic((uint64_t *)p); break; \ - default: __x = 0; __bad_atomic_size(); break; \ - } \ - __x; \ + union { typeof(*p) val; char c[0]; } x_; \ + read_atomic_size(p, x_.c, sizeof(*p)); \ + x_.val; \ }) #define write_atomic(p, x) ({ \ -- generated by git-patchbot for /home/xen/git/xen.git#staging
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