2018-01-13 18:48:47

by Karim Eshapa

Subject: [PATCH] Remove structure passing and assignment to save stack and no coping structures.

Signed-off-by: Karim Eshapa <[email protected]>

Thanks,
Karim
---
include/linux/tnum.h | 2 +-
kernel/bpf/tnum.c | 13 +++++++------
kernel/bpf/verifier.c | 12 ++++++++----
3 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/include/linux/tnum.h b/include/linux/tnum.h
index 0d2d3da..ddb1250 100644
--- a/include/linux/tnum.h
+++ b/include/linux/tnum.h
@@ -26,7 +26,7 @@ struct tnum tnum_lshift(struct tnum a, u8 shift);
/* Shift a tnum right (by a fixed shift) */
struct tnum tnum_rshift(struct tnum a, u8 shift);
/* Add two tnums, return @a + @b */
-struct tnum tnum_add(struct tnum a, struct tnum b);
+void tnum_add(struct tnum *res, struct tnum *a, struct tnum *b);
/* Subtract two tnums, return @a - @b */
struct tnum tnum_sub(struct tnum a, struct tnum b);
/* Bitwise-AND, return @a & @b */
diff --git a/kernel/bpf/tnum.c b/kernel/bpf/tnum.c
index 1f4bf68..f7f8b10 100644
--- a/kernel/bpf/tnum.c
+++ b/kernel/bpf/tnum.c
@@ -43,16 +43,17 @@ struct tnum tnum_rshift(struct tnum a, u8 shift)
return TNUM(a.value >> shift, a.mask >> shift);
}

-struct tnum tnum_add(struct tnum a, struct tnum b)
+void tnum tnum_add(struct tnum *res, struct tnum *a, struct tnum *b)
{
u64 sm, sv, sigma, chi, mu;

- sm = a.mask + b.mask;
- sv = a.value + b.value;
+ sm = a->mask + b->mask;
+ sv = a->value + b->value;
sigma = sm + sv;
chi = sigma ^ sv;
- mu = chi | a.mask | b.mask;
- return TNUM(sv & ~mu, mu);
+ mu = chi | a->mask | b->mask;
+ res->value = (sv & ~mu);
+ res->mask = mu;
}

struct tnum tnum_sub(struct tnum a, struct tnum b)
@@ -102,7 +103,7 @@ static struct tnum hma(struct tnum acc, u64 value, u64 mask)
{
while (mask) {
if (mask & 1)
- acc = tnum_add(acc, TNUM(0, value));
+ tnum_add(&acc, &acc, &TNUM(0, value));
mask >>= 1;
value <<= 1;
}
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index b414d6b..4acc16c 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -999,7 +999,8 @@ static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
*/
ip_align = 2;

- reg_off = tnum_add(reg->var_off, tnum_const(ip_align + reg->off + off));
+ tnum_add(&reg_off, &reg->var_off,
+ &tnum_const(ip_align + reg->off + off));
if (!tnum_is_aligned(reg_off, size)) {
char tn_buf[48];

@@ -1024,7 +1025,8 @@ static int check_generic_ptr_alignment(struct bpf_verifier_env *env,
if (!strict || size == 1)
return 0;

- reg_off = tnum_add(reg->var_off, tnum_const(reg->off + off));
+ tnum_add(&reg_off, &reg->var_off,
+ &tnum_const(reg->off + off));
if (!tnum_is_aligned(reg_off, size)) {
char tn_buf[48];

@@ -1971,7 +1973,8 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env,
dst_reg->umin_value = umin_ptr + umin_val;
dst_reg->umax_value = umax_ptr + umax_val;
}
- dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off);
+ tnum_add(&dst_reg->var_off, &ptr_reg->var_off,
+ &off_reg->var_off);
dst_reg->off = ptr_reg->off;
if (reg_is_pkt_pointer(ptr_reg)) {
dst_reg->id = ++env->id_gen;
@@ -2108,7 +2111,8 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env,
dst_reg->umin_value += umin_val;
dst_reg->umax_value += umax_val;
}
- dst_reg->var_off = tnum_add(dst_reg->var_off, src_reg.var_off);
+ tnum_add(&dst_reg->var_off, &dst_reg->var_off,
+ &src_reg.var_off);
break;
case BPF_SUB:
if (signed_sub_overflows(dst_reg->smin_value, smax_val) ||
--
2.7.4