> On Aug 27, 2024, at 00:36, Charlie Jenkins <charlie@xxxxxxxxxxxx> wrote: > > The hint address should not forcefully restrict the addresses returned > by mmap as this causes mmap to report ENOMEM when there is memory still > available. > Fixing in this way will break userspace on Sv57 machines as some issues mentioned in the patch [1]. I suggest restricting to BIT(47) by default, like patch [2], to align with kernel behavior on x86 and aarch64, and this does exist on x86 and aarch64 for quite a long time. In that way, we will also solve the problem mentioned in the first patch [1], as QEMU enables Sv57 by default now and will not break userspace. [1] https://lore.kernel.org/linux-riscv/20230809232218.849726-1-charlie@xxxxxxxxxxxx/ [2] https://lore.kernel.org/linux-riscv/tencent_B2D0435BC011135736262764B511994F4805@xxxxxx/ Thanks, Yangyu Chen > Signed-off-by: Charlie Jenkins <charlie@xxxxxxxxxxxx> > Fixes: b5b4287accd7 ("riscv: mm: Use hint address in mmap if available") > Fixes: add2cc6b6515 ("RISC-V: mm: Restrict address space for sv39,sv48,sv57") > Closes: https://lore.kernel.org/linux-kernel/ZbxTNjQPFKBatMq+@ghost/T/#mccb1890466bf5a488c9ce7441e57e42271895765 > --- > arch/riscv/include/asm/processor.h | 26 ++------------------------ > 1 file changed, 2 insertions(+), 24 deletions(-) > > diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/processor.h > index 8702b8721a27..efa1b3519b23 100644 > --- a/arch/riscv/include/asm/processor.h > +++ b/arch/riscv/include/asm/processor.h > @@ -14,36 +14,14 @@ > > #include <asm/ptrace.h> > > -/* > - * addr is a hint to the maximum userspace address that mmap should provide, so > - * this macro needs to return the largest address space available so that > - * mmap_end < addr, being mmap_end the top of that address space. > - * See Documentation/arch/riscv/vm-layout.rst for more details. > - */ > #define arch_get_mmap_end(addr, len, flags) \ > ({ \ > - unsigned long mmap_end; \ > - typeof(addr) _addr = (addr); \ > - if ((_addr) == 0 || is_compat_task() || \ > - ((_addr + len) > BIT(VA_BITS - 1))) \ > - mmap_end = STACK_TOP_MAX; \ > - else \ > - mmap_end = (_addr + len); \ > - mmap_end; \ > + STACK_TOP_MAX; \ > }) > > #define arch_get_mmap_base(addr, base) \ > ({ \ > - unsigned long mmap_base; \ > - typeof(addr) _addr = (addr); \ > - typeof(base) _base = (base); \ > - unsigned long rnd_gap = DEFAULT_MAP_WINDOW - (_base); \ > - if ((_addr) == 0 || is_compat_task() || \ > - ((_addr + len) > BIT(VA_BITS - 1))) \ > - mmap_base = (_base); \ > - else \ > - mmap_base = (_addr + len) - rnd_gap; \ > - mmap_base; \ > + base; \ > }) > > #ifdef CONFIG_64BIT > > -- > 2.45.0 >
