nfp: bpf: add helpers for updating immediate instructions

Immediate loads are used to load the return address of a helper.
We need to be able to update those loads for relocations.
Immediate loads can be slightly more complex and spread over
two instructions in general, but here we only care about simple
loads of small (< 65k) constants, so complex cases are not handled.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_asm.c b/drivers/net/ethernet/netronome/nfp/nfp_asm.c
index 9ee3a3f60cc7ae65041157dca64f1ecb004f10f1..3f6952b66a4979cc9bcc9d1333367a61c315f1b3 100644 (file)
--- a/drivers/net/ethernet/netronome/nfp/nfp_asm.c
+++ b/drivers/net/ethernet/netronome/nfp/nfp_asm.c
@@ -50,6 +50,11 @@ const struct cmd_tgt_act cmd_tgt_act[__CMD_TGT_MAP_SIZE] = {
        [CMD_TGT_READ_SWAP_LE] =        { 0x03, 0x40 },
 };
 
+static bool unreg_is_imm(u16 reg)
+{
+       return (reg & UR_REG_IMM) == UR_REG_IMM;
+}
+
 u16 br_get_offset(u64 instr)
 {
        u16 addr_lo, addr_hi;
@@ -80,6 +85,59 @@ void br_add_offset(u64 *instr, u16 offset)
        br_set_offset(instr, addr + offset);
 }
 
+static bool immed_can_modify(u64 instr)
+{
+       if (FIELD_GET(OP_IMMED_INV, instr) ||
+           FIELD_GET(OP_IMMED_SHIFT, instr) ||
+           FIELD_GET(OP_IMMED_WIDTH, instr) != IMMED_WIDTH_ALL) {
+               pr_err("Can't decode/encode immed!\n");
+               return false;
+       }
+       return true;
+}
+
+u16 immed_get_value(u64 instr)
+{
+       u16 reg;
+
+       if (!immed_can_modify(instr))
+               return 0;
+
+       reg = FIELD_GET(OP_IMMED_A_SRC, instr);
+       if (!unreg_is_imm(reg))
+               reg = FIELD_GET(OP_IMMED_B_SRC, instr);
+
+       return (reg & 0xff) | FIELD_GET(OP_IMMED_IMM, instr);
+}
+
+void immed_set_value(u64 *instr, u16 immed)
+{
+       if (!immed_can_modify(*instr))
+               return;
+
+       if (unreg_is_imm(FIELD_GET(OP_IMMED_A_SRC, *instr))) {
+               *instr &= ~FIELD_PREP(OP_IMMED_A_SRC, 0xff);
+               *instr |= FIELD_PREP(OP_IMMED_A_SRC, immed & 0xff);
+       } else {
+               *instr &= ~FIELD_PREP(OP_IMMED_B_SRC, 0xff);
+               *instr |= FIELD_PREP(OP_IMMED_B_SRC, immed & 0xff);
+       }
+
+       *instr &= ~OP_IMMED_IMM;
+       *instr |= FIELD_PREP(OP_IMMED_IMM, immed >> 8);
+}
+
+void immed_add_value(u64 *instr, u16 offset)
+{
+       u16 val;
+
+       if (!immed_can_modify(*instr))
+               return;
+
+       val = immed_get_value(*instr);
+       immed_set_value(instr, val + offset);
+}
+
 static u16 nfp_swreg_to_unreg(swreg reg, bool is_dst)
 {
        bool lm_id, lm_dec = false;

diff --git a/drivers/net/ethernet/netronome/nfp/nfp_asm.h b/drivers/net/ethernet/netronome/nfp/nfp_asm.h
index 20e51cb60e69b69e4514414c9d7065207ec98786..5f9291db98e065e3de119036f73bcb284f72e12c 100644 (file)
--- a/drivers/net/ethernet/netronome/nfp/nfp_asm.h
+++ b/drivers/net/ethernet/netronome/nfp/nfp_asm.h
@@ -138,6 +138,10 @@ enum immed_shift {
        IMMED_SHIFT_2B = 2,
 };
 
+u16 immed_get_value(u64 instr);
+void immed_set_value(u64 *instr, u16 immed);
+void immed_add_value(u64 *instr, u16 offset);
+
 #define OP_SHF_BASE            0x08000000000ULL
 #define OP_SHF_A_SRC           0x000000000ffULL
 #define OP_SHF_SC              0x00000000300ULL