]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commitdiff
mips, bpf: Optimize loading of 64-bit constants
authorJohan Almbladh <johan.almbladh@anyfinetworks.com>
Thu, 7 Oct 2021 14:28:28 +0000 (16:28 +0200)
committerDaniel Borkmann <daniel@iogearbox.net>
Thu, 7 Oct 2021 21:51:29 +0000 (23:51 +0200)
This patch shaves off a few instructions when loading sparse 64-bit
constants to register. The change is covered by additional tests in
lib/test_bpf.c.

Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20211007142828.634182-1-johan.almbladh@anyfinetworks.com
arch/mips/net/bpf_jit_comp64.c

index 1f1f7b87f213ebfe330c83c8376f1b2c10984584..815ade7242278a62abc6f75f567d1cd4e3d89622 100644 (file)
@@ -131,19 +131,25 @@ static void emit_mov_i64(struct jit_context *ctx, u8 dst, u64 imm64)
                emit(ctx, ori, dst, dst, (u16)imm64 & 0xffff);
        } else {
                u8 acc = MIPS_R_ZERO;
+               int shift = 0;
                int k;
 
                for (k = 0; k < 4; k++) {
                        u16 half = imm64 >> (48 - 16 * k);
 
                        if (acc == dst)
-                               emit(ctx, dsll, dst, dst, 16);
+                               shift += 16;
 
                        if (half) {
+                               if (shift)
+                                       emit(ctx, dsll_safe, dst, dst, shift);
                                emit(ctx, ori, dst, acc, half);
                                acc = dst;
+                               shift = 0;
                        }
                }
+               if (shift)
+                       emit(ctx, dsll_safe, dst, dst, shift);
        }
        clobber_reg(ctx, dst);
 }