From: Arnd Bergmann arnd@arndb.de
[ Upstream commit c7c386fbc20262c1d911c615c65db6a58667d92c ]
gcc warns about undefined behavior the vmalloc code when building with CONFIG_ARM64_PA_BITS_52, when the 'idx++' in the argument to __phys_to_pte_val() is evaluated twice:
mm/vmalloc.c: In function 'vmap_pfn_apply': mm/vmalloc.c:2800:58: error: operation on 'data->idx' may be undefined [-Werror=sequence-point] 2800 | *pte = pte_mkspecial(pfn_pte(data->pfns[data->idx++], data->prot)); | ~~~~~~~~~^~ arch/arm64/include/asm/pgtable-types.h:25:37: note: in definition of macro '__pte' 25 | #define __pte(x) ((pte_t) { (x) } ) | ^ arch/arm64/include/asm/pgtable.h:80:15: note: in expansion of macro '__phys_to_pte_val' 80 | __pte(__phys_to_pte_val((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot)) | ^~~~~~~~~~~~~~~~~ mm/vmalloc.c:2800:30: note: in expansion of macro 'pfn_pte' 2800 | *pte = pte_mkspecial(pfn_pte(data->pfns[data->idx++], data->prot)); | ^~~~~~~
I have no idea why this never showed up earlier, but the safest workaround appears to be changing those macros into inline functions so the arguments get evaluated only once.
Cc: Matthew Wilcox willy@infradead.org Fixes: 75387b92635e ("arm64: handle 52-bit physical addresses in page table entries") Signed-off-by: Arnd Bergmann arnd@arndb.de Link: https://lore.kernel.org/r/20211105075414.2553155-1-arnd@kernel.org Signed-off-by: Will Deacon will@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm64/include/asm/pgtable.h | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index dfa76afa0ccff..72f95c6a70519 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -67,9 +67,15 @@ extern unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]; * page table entry, taking care of 52-bit addresses. */ #ifdef CONFIG_ARM64_PA_BITS_52 -#define __pte_to_phys(pte) \ - ((pte_val(pte) & PTE_ADDR_LOW) | ((pte_val(pte) & PTE_ADDR_HIGH) << 36)) -#define __phys_to_pte_val(phys) (((phys) | ((phys) >> 36)) & PTE_ADDR_MASK) +static inline phys_addr_t __pte_to_phys(pte_t pte) +{ + return (pte_val(pte) & PTE_ADDR_LOW) | + ((pte_val(pte) & PTE_ADDR_HIGH) << 36); +} +static inline pteval_t __phys_to_pte_val(phys_addr_t phys) +{ + return (phys | (phys >> 36)) & PTE_ADDR_MASK; +} #else #define __pte_to_phys(pte) (pte_val(pte) & PTE_ADDR_MASK) #define __phys_to_pte_val(phys) (phys)