[RFC PATCH V3 22/43] rv64ilp32_abi: bpf: Change KERN_ARENA_SZ to 256MiB

[guoren]

From: "Guo Ren (Alibaba DAMO Academy)" <guo...@kernel.org>

The RV64ILP32 ABI limits the vmalloc range to 512MB, hence the
arena kernel range is set to 256MiB instead of 4GiB.

Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guo...@kernel.org>
---
 kernel/bpf/arena.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c
index 870aeb51d70a..4eb99f83d4a1 100644
--- a/kernel/bpf/arena.c
+++ b/kernel/bpf/arena.c
@@ -40,7 +40,14 @@
 
 /* number of bytes addressable by LDX/STX insn with 16-bit 'off' field */
 #define GUARD_SZ (1ull << sizeof_field(struct bpf_insn, off) * 8)
-#define KERN_VM_SZ (SZ_4G + GUARD_SZ)
+
+#if BITS_PER_LONG == 64
+#define KERN_ARENA_SZ SZ_4G
+#else
+#define KERN_ARENA_SZ SZ_256M
+#endif
+
+#define KERN_VM_SZ (KERN_ARENA_SZ + GUARD_SZ)
 
 struct bpf_arena {
        struct bpf_map map;
@@ -115,7 +122,7 @@ static struct bpf_map *arena_map_alloc(union bpf_attr *attr)
                return ERR_PTR(-EINVAL);
 
        vm_range = (u64)attr->max_entries * PAGE_SIZE;
-       if (vm_range > SZ_4G)
+       if (vm_range > KERN_ARENA_SZ)
                return ERR_PTR(-E2BIG);
 
        if ((attr->map_extra >> 32) != ((attr->map_extra + vm_range - 1) >> 32))
@@ -321,7 +328,7 @@ static unsigned long arena_get_unmapped_area(struct file 
*filp, unsigned long ad
 
        if (pgoff)
                return -EINVAL;
-       if (len > SZ_4G)
+       if (len > KERN_ARENA_SZ)
                return -E2BIG;
 
        /* if user_vm_start was specified at arena creation time */
@@ -337,12 +344,14 @@ static unsigned long arena_get_unmapped_area(struct file 
*filp, unsigned long ad
        ret = mm_get_unmapped_area(current->mm, filp, addr, len * 2, 0, flags);
        if (IS_ERR_VALUE(ret))
                return ret;
+#if BITS_PER_LONG == 64
        if ((ret >> 32) == ((ret + len - 1) >> 32))
                return ret;
+#endif
        if (WARN_ON_ONCE(arena->user_vm_start))
                /* checks at map creation time should prevent this */
                return -EFAULT;
-       return round_up(ret, SZ_4G);
+       return round_up(ret, KERN_ARENA_SZ);
 }
 
 static int arena_map_mmap(struct bpf_map *map, struct vm_area_struct *vma)
@@ -366,7 +375,7 @@ static int arena_map_mmap(struct bpf_map *map, struct 
vm_area_struct *vma)
                return -EBUSY;
 
        /* Earlier checks should prevent this */
-       if (WARN_ON_ONCE(vma->vm_end - vma->vm_start > SZ_4G || vma->vm_pgoff))
+       if (WARN_ON_ONCE(vma->vm_end - vma->vm_start > KERN_ARENA_SZ || 
vma->vm_pgoff))
                return -EFAULT;
 
        if (remember_vma(arena, vma))
-- 
2.40.1