From: Nicholas Piggin npiggin@gmail.com
[ Upstream commit 6bb25170d7a44ef0ed9677814600f0785e7421d1 ]
pfn_pte is never given a pte above the addressable physical memory limit, so the masking is redundant. In case of a software bug, it is not obviously better to silently truncate the pfn than to corrupt the pte (either one will result in memory corruption or crashes), so there is no reason to add this to the fast path.
Add VM_BUG_ON to catch cases where the pfn is invalid. These would catch the create_section_mapping bug fixed by a previous commit.
[16885.256466] ------------[ cut here ]------------ [16885.256492] kernel BUG at arch/powerpc/include/asm/book3s/64/pgtable.h:612! cpu 0x0: Vector: 700 (Program Check) at [c0000000ee0a36d0] pc: c000000000080738: __map_kernel_page+0x248/0x6f0 lr: c000000000080ac0: __map_kernel_page+0x5d0/0x6f0 sp: c0000000ee0a3960 msr: 9000000000029033 current = 0xc0000000ec63b400 paca = 0xc0000000017f0000 irqmask: 0x03 irq_happened: 0x01 pid = 85, comm = sh kernel BUG at arch/powerpc/include/asm/book3s/64/pgtable.h:612! Linux version 5.3.0-rc1-00001-g0fe93e5f3394 enter ? for help [c0000000ee0a3a00] c000000000d37378 create_physical_mapping+0x260/0x360 [c0000000ee0a3b10] c000000000d370bc create_section_mapping+0x1c/0x3c [c0000000ee0a3b30] c000000000071f54 arch_add_memory+0x74/0x130
Signed-off-by: Nicholas Piggin npiggin@gmail.com Reviewed-by: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/20190724084638.24982-5-npiggin@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/include/asm/book3s/64/pgtable.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h index 4dd13b503dbbd..5f37d8c3b4798 100644 --- a/arch/powerpc/include/asm/book3s/64/pgtable.h +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h @@ -555,8 +555,10 @@ static inline int pte_present(pte_t pte) */ static inline pte_t pfn_pte(unsigned long pfn, pgprot_t pgprot) { - return __pte((((pte_basic_t)(pfn) << PAGE_SHIFT) & PTE_RPN_MASK) | - pgprot_val(pgprot)); + VM_BUG_ON(pfn >> (64 - PAGE_SHIFT)); + VM_BUG_ON((pfn << PAGE_SHIFT) & ~PTE_RPN_MASK); + + return __pte(((pte_basic_t)pfn << PAGE_SHIFT) | pgprot_val(pgprot)); }
static inline unsigned long pte_pfn(pte_t pte)