Fix XLEN assumption in riscv_instr_pkg

[dpetrisko]

This assumption causes an unaligned store on 64b processor in some cases. This fix should preserve behavior on 32b processors but allow for aligned 64b store

[dpetrisko]

Hi can someone take a look at this?

[talhashahzad12345]

The tests I ran using RV64imc, ran into this issue where ecall would go to mmode handler and there unaligned store would restart mmode handler where mmode handler has no direct handling of unaligned stores. This fix has worked for me and makes sense.

[il-steffen]

Looks like there are more instances of this:

diff --git a/src/riscv_directed_instr_lib.sv b/src/riscv_directed_instr_lib.sv
index f3bc708..cd0e2b9 100644
--- a/src/riscv_directed_instr_lib.sv
+++ b/src/riscv_directed_instr_lib.sv
@@ -372,7 +372,7 @@ class riscv_pop_stack_instr extends riscv_rand_instr_stream;
   function void init();
     reserved_rd = {cfg.ra};
     num_of_reg_to_save = saved_regs.size();
-    if(num_of_reg_to_save * 4 > stack_len) begin
+    if(num_of_reg_to_save * XLEN/8 > stack_len) begin
       `uvm_fatal(get_full_name(), $sformatf("stack len [%0d] is not enough to store %d regs",
                  stack_len, num_of_reg_to_save))
     end
diff --git a/src/riscv_instr_pkg.sv b/src/riscv_instr_pkg.sv
index 9620766..c305485 100644
--- a/src/riscv_instr_pkg.sv
+++ b/src/riscv_instr_pkg.sv
@@ -1380,7 +1380,7 @@ package riscv_instr_pkg;
     string store_instr = (XLEN == 32) ? "sw" : "sd";
     if (scratch inside {implemented_csr}) begin
       // Push USP from gpr.SP onto the kernel stack
-      instr.push_back($sformatf("addi x%0d, x%0d, -4", tp, tp));
+      instr.push_back($sformatf("addi x%0d, x%0d, -%0d", tp, tp, (XLEN/8)));
       instr.push_back($sformatf("%0s  x%0d, (x%0d)", store_instr, sp, tp));
       // Move KSP to gpr.SP
       instr.push_back($sformatf("add x%0d, x%0d, zero", sp, tp));
@@ -1435,7 +1435,7 @@ package riscv_instr_pkg;
       instr.push_back($sformatf("add x%0d, x%0d, zero", tp, sp));
       // Pop USP from the kernel stack, move back to gpr.SP
       instr.push_back($sformatf("%0s  x%0d, (x%0d)", load_instr, sp, tp));
-      instr.push_back($sformatf("addi x%0d, x%0d, 4", tp, tp));
+      instr.push_back($sformatf("addi x%0d, x%0d, %0d", tp, tp, (XLEN/8)));
     end
   endfunction