From: Serge Semin <fancer.lancer@xxxxxxxxx> [ Upstream commit 93fa5b280761a4dbb14c5330f260380385ab2b49 ] There are situations when memory regions coming from dts may be too big for the platform physical address space. This especially concerns XPA-capable systems. Bootloader may determine more than 4GB memory available and pass it to the kernel over dts memory node, while kernel is built without XPA/64BIT support. In this case the region may either simply be truncated by add_memory_region() method or by u64->phys_addr_t type casting. But in worst case the method can even drop the memory region if it exceeds PHYS_ADDR_MAX size. So lets make sure the retrieved from dts memory regions are valid, and if some of them aren't, just manually truncate them with a warning printed out. Signed-off-by: Serge Semin <fancer.lancer@xxxxxxxxx> Signed-off-by: Paul Burton <paul.burton@xxxxxxxx> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Cc: James Hogan <jhogan@xxxxxxxxxx> Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Cc: Thomas Bogendoerfer <tbogendoerfer@xxxxxxx> Cc: Huacai Chen <chenhc@xxxxxxxxxx> Cc: Stefan Agner <stefan@xxxxxxxx> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx> Cc: Juergen Gross <jgross@xxxxxxxx> Cc: Serge Semin <Sergey.Semin@xxxxxxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxxx Cc: linux-kernel@xxxxxxxxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- arch/mips/kernel/prom.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/arch/mips/kernel/prom.c b/arch/mips/kernel/prom.c index 89950b7bf536b..bdaf3536241a2 100644 --- a/arch/mips/kernel/prom.c +++ b/arch/mips/kernel/prom.c @@ -41,7 +41,19 @@ char *mips_get_machine_name(void) #ifdef CONFIG_USE_OF void __init early_init_dt_add_memory_arch(u64 base, u64 size) { - return add_memory_region(base, size, BOOT_MEM_RAM); + if (base >= PHYS_ADDR_MAX) { + pr_warn("Trying to add an invalid memory region, skipped\n"); + return; + } + + /* Truncate the passed memory region instead of type casting */ + if (base + size - 1 >= PHYS_ADDR_MAX || base + size < base) { + pr_warn("Truncate memory region %llx @ %llx to size %llx\n", + size, base, PHYS_ADDR_MAX - base); + size = PHYS_ADDR_MAX - base; + } + + add_memory_region(base, size, BOOT_MEM_RAM); } int __init early_init_dt_reserve_memory_arch(phys_addr_t base, -- 2.20.1