After the V!=R rework (commit c98d2ecae08f ("s390/mm: Uncouple physical
vs virtual address spaces")), kernel and BPF programs are allocated
within a 4G region, making it possible to use relative addressing to
directly use kernel functions from BPF code.
Add two new macros for calling kernel functions from BPF code:
EMIT6_PCREL_RILB_PTR() and EMIT6_PCREL_RILC_PTR(). Factor out parts
of the existing macros that are helpful for implementing the new ones.
Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx>
---
arch/s390/net/bpf_jit_comp.c | 60 +++++++++++++++++++++++++-----------
1 file changed, 42 insertions(+), 18 deletions(-)
diff --git a/arch/s390/net/bpf_jit_comp.c b/arch/s390/net/bpf_jit_comp.c
index 6f22b5199c20..70a93e03bfb3 100644
--- a/arch/s390/net/bpf_jit_comp.c
+++ b/arch/s390/net/bpf_jit_comp.c
@@ -127,6 +127,18 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
jit->seen_regs |= (1 << r1);
}
+static s32 off_to_pcrel(struct bpf_jit *jit, u32 off)
+{
+ return off - jit->prg;
+}
+
+static s64 ptr_to_pcrel(struct bpf_jit *jit, const void *ptr)
+{
+ if (jit->prg_buf)
+ return (const u8 *)ptr - ((const u8 *)jit->prg_buf + jit->prg);
+ return 0;
+}
+
#define REG_SET_SEEN(b1) \
({ \
reg_set_seen(jit, b1); \
@@ -201,7 +213,7 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
#define EMIT4_PCREL_RIC(op, mask, target) \
({ \
- int __rel = ((target) - jit->prg) / 2; \
+ int __rel = off_to_pcrel(jit, target) / 2; \
_EMIT4((op) | (mask) << 20 | (__rel & 0xffff)); \
})
@@ -239,7 +251,7 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
#define EMIT6_PCREL_RIEB(op1, op2, b1, b2, mask, target) \
({ \
- unsigned int rel = (int)((target) - jit->prg) / 2; \
+ unsigned int rel = off_to_pcrel(jit, target) / 2; \
_EMIT6((op1) | reg(b1, b2) << 16 | (rel & 0xffff), \
(op2) | (mask) << 12); \
REG_SET_SEEN(b1); \
@@ -248,7 +260,7 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
#define EMIT6_PCREL_RIEC(op1, op2, b1, imm, mask, target) \
({ \
- unsigned int rel = (int)((target) - jit->prg) / 2; \
+ unsigned int rel = off_to_pcrel(jit, target) / 2; \
_EMIT6((op1) | (reg_high(b1) | (mask)) << 16 | \
(rel & 0xffff), (op2) | ((imm) & 0xff) << 8); \
REG_SET_SEEN(b1); \
@@ -257,29 +269,41 @@ static inline void reg_set_seen(struct bpf_jit *jit, u32 b1)
#define EMIT6_PCREL(op1, op2, b1, b2, i, off, mask) \
({ \
- int rel = (addrs[(i) + (off) + 1] - jit->prg) / 2; \
+ int rel = off_to_pcrel(jit, addrs[(i) + (off) + 1]) / 2;\
_EMIT6((op1) | reg(b1, b2) << 16 | (rel & 0xffff), (op2) | (mask));\
REG_SET_SEEN(b1); \
REG_SET_SEEN(b2); \
})
+static void emit6_pcrel_ril(struct bpf_jit *jit, u32 op, s64 pcrel)
+{
+ u32 pc32dbl = (s32)(pcrel / 2);
+
+ _EMIT6(op | pc32dbl >> 16, pc32dbl & 0xffff);
+}
+
+static void emit6_pcrel_rilb(struct bpf_jit *jit, u32 op, u8 b, s64 pcrel)
+{
+ emit6_pcrel_ril(jit, op | reg_high(b) << 16, pcrel);
+ REG_SET_SEEN(b);
+}
+
#define EMIT6_PCREL_RILB(op, b, target) \
-({ \
- unsigned int rel = (int)((target) - jit->prg) / 2; \
- _EMIT6((op) | reg_high(b) << 16 | rel >> 16, rel & 0xffff);\
- REG_SET_SEEN(b); \
-})
+ emit6_pcrel_rilb(jit, op, b, off_to_pcrel(jit, target))
-#define EMIT6_PCREL_RIL(op, target) \
-({ \
- unsigned int rel = (int)((target) - jit->prg) / 2; \
- _EMIT6((op) | rel >> 16, rel & 0xffff); \
-})
+#define EMIT6_PCREL_RILB_PTR(op, b, target_ptr) \
+ emit6_pcrel_rilb(jit, op, b, ptr_to_pcrel(jit, target_ptr))
+
+static void emit6_pcrel_rilc(struct bpf_jit *jit, u32 op, u8 mask, s64 pcrel)
+{
+ emit6_pcrel_ril(jit, op | mask << 20, pcrel);
+}
#define EMIT6_PCREL_RILC(op, mask, target) \
-({ \
- EMIT6_PCREL_RIL((op) | (mask) << 20, (target)); \
-})
+ emit6_pcrel_rilc(jit, op, mask, off_to_pcrel(jit, target))
+
+#define EMIT6_PCREL_RILC_PTR(op, mask, target_ptr) \
+ emit6_pcrel_rilc(jit, op, mask, ptr_to_pcrel(jit, target_ptr))
#define _EMIT6_IMM(op, imm) \
({ \
@@ -503,7 +527,7 @@ static void bpf_skip(struct bpf_jit *jit, int size)
{
if (size >= 6 && !is_valid_rel(size)) {
/* brcl 0xf,size */
- EMIT6_PCREL_RIL(0xc0f4000000, size);
+ EMIT6_PCREL_RILC(0xc0040000, 0xf, size);
size -= 6;
} else if (size >= 4 && is_valid_rel(size)) {
/* brc 0xf,size */
--
2.49.0
