ebpf: migrate bpf_prog's flags to bitfield

As we need to add further flags to the bpf_prog structure, lets migrate
both bools to a bitfield representation. The size of the base structure
(excluding insns) remains unchanged at 40 bytes.

Add also tags for the kmemchecker, so that it doesn't throw false
positives. Even in case gcc would generate suboptimal code, it's not
being accessed in performance critical paths.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/arm/net/bpf_jit_32.c

@@ -1047,7 +1047,7 @@ void bpf_jit_compile(struct bpf_prog *fp)
 
 	set_memory_ro((unsigned long)header, header->pages);
 	fp->bpf_func = (void *)ctx.target;
-	fp->jited = true;
+	fp->jited = 1;
 out:
 	kfree(ctx.offsets);
 	return;

arch/arm64/net/bpf_jit_comp.c

@@ -744,7 +744,7 @@ void bpf_int_jit_compile(struct bpf_prog *prog)
 
 	set_memory_ro((unsigned long)header, header->pages);
 	prog->bpf_func = (void *)ctx.image;
-	prog->jited = true;
+	prog->jited = 1;
 out:
 	kfree(ctx.offset);
 }

arch/mips/net/bpf_jit.c

@@ -1251,7 +1251,7 @@ void bpf_jit_compile(struct bpf_prog *fp)
 		bpf_jit_dump(fp->len, alloc_size, 2, ctx.target);
 
 	fp->bpf_func = (void *)ctx.target;
-	fp->jited = true;
+	fp->jited = 1;
 
 out:
 	kfree(ctx.offsets);

arch/powerpc/net/bpf_jit_comp.c

@@ -679,7 +679,7 @@ void bpf_jit_compile(struct bpf_prog *fp)
 		((u64 *)image)[1] = local_paca->kernel_toc;
 #endif
 		fp->bpf_func = (void *)image;
-		fp->jited = true;
+		fp->jited = 1;
 	}
 out:
 	kfree(addrs);

arch/s390/net/bpf_jit_comp.c

@@ -1310,7 +1310,7 @@ void bpf_int_jit_compile(struct bpf_prog *fp)
 	if (jit.prg_buf) {
 		set_memory_ro((unsigned long)header, header->pages);
 		fp->bpf_func = (void *) jit.prg_buf;
-		fp->jited = true;
+		fp->jited = 1;
 	}
 free_addrs:
 	kfree(jit.addrs);

arch/sparc/net/bpf_jit_comp.c

@@ -812,7 +812,7 @@ cond_branch:			f_offset = addrs[i + filter[i].jf];
 	if (image) {
 		bpf_flush_icache(image, image + proglen);
 		fp->bpf_func = (void *)image;
-		fp->jited = true;
+		fp->jited = 1;
 	}
 out:
 	kfree(addrs);

arch/x86/net/bpf_jit_comp.c

@@ -1109,7 +1109,7 @@ void bpf_int_jit_compile(struct bpf_prog *prog)
 		bpf_flush_icache(header, image + proglen);
 		set_memory_ro((unsigned long)header, header->pages);
 		prog->bpf_func = (void *)image;
-		prog->jited = true;
+		prog->jited = 1;
 	}
 out:
 	kfree(addrs);

include/linux/filter.h

@@ -326,8 +326,10 @@ struct bpf_binary_header {
 
 struct bpf_prog {
 	u16			pages;		/* Number of allocated pages */
-	bool			jited;		/* Is our filter JIT'ed? */
+	kmemcheck_bitfield_begin(meta);
-	bool			gpl_compatible;	/* Is our filter GPL compatible? */
+	u16			jited:1,	/* Is our filter JIT'ed? */
+				gpl_compatible:1; /* Is filter GPL compatible? */
+	kmemcheck_bitfield_end(meta);
 	u32			len;		/* Number of filter blocks */
 	enum bpf_prog_type	type;		/* Type of BPF program */
 	struct bpf_prog_aux	*aux;		/* Auxiliary fields */

kernel/bpf/core.c

@@ -82,6 +82,8 @@ struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags)
 	if (fp == NULL)
 		return NULL;
 
+	kmemcheck_annotate_bitfield(fp, meta);
+
 	aux = kzalloc(sizeof(*aux), GFP_KERNEL | gfp_extra_flags);
 	if (aux == NULL) {
 		vfree(fp);
@@ -110,6 +112,8 @@ struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
 
 	fp = __vmalloc(size, gfp_flags, PAGE_KERNEL);
 	if (fp != NULL) {
+		kmemcheck_annotate_bitfield(fp, meta);
+
 		memcpy(fp, fp_old, fp_old->pages * PAGE_SIZE);
 		fp->pages = size / PAGE_SIZE;
 

kernel/bpf/syscall.c

@@ -553,10 +553,10 @@ static int bpf_prog_load(union bpf_attr *attr)
 		goto free_prog;
 
 	prog->orig_prog = NULL;
-	prog->jited = false;
+	prog->jited = 0;
 
 	atomic_set(&prog->aux->refcnt, 1);
-	prog->gpl_compatible = is_gpl;
+	prog->gpl_compatible = is_gpl ? 1 : 0;
 
 	/* find program type: socket_filter vs tracing_filter */
 	err = find_prog_type(type, prog);

net/core/filter.c

@@ -1001,7 +1001,7 @@ static struct bpf_prog *bpf_prepare_filter(struct bpf_prog *fp,
 	int err;
 
 	fp->bpf_func = NULL;
-	fp->jited = false;
+	fp->jited = 0;
 
 	err = bpf_check_classic(fp->insns, fp->len);
 	if (err) {