[riscv] Allow apply_relocs() to use non-inline relocation records

The address of the compressed relocation records is currently
calculated implicitly relative to the program counter.  This requires
the relocation records to be copied as part of relocation to a new
physical address, so that they can be reapplied (if needed) after
copying iPXE to the new physical address.

Since the relocation destination will never overlap the original iPXE
image, and since the relocation records will not be needed further
after completing relocation, we can avoid the need to copy the records
by passing in a pointer to the relocation records present in the
original iPXE image.

Pass the compressed relocation record address as an explicit parameter
to apply_relocs(), rather than being implicit in the program counter.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

diff --git a/src/arch/riscv/prefix/libprefix.S b/src/arch/riscv/prefix/libprefix.S
index 42e301e108401401b3922362bccb82a843d6ed0c..9a706af50893a05b9e0ebb406a217f948529da45 100644 (file)
--- a/src/arch/riscv/prefix/libprefix.S
+++ b/src/arch/riscv/prefix/libprefix.S
@@ -227,7 +227,9 @@ print_hex_value_alt:
  * records are overlaid with .bss).  It does not require a valid stack
  * pointer.
  *
- * Parameters: none (address is implicit in the program counter)
+ * Parameters: none
+ *
+ *   a0 - Relocation records
  *
  * Returns: none
  *
@@ -241,27 +243,26 @@ print_hex_value_alt:
 apply_relocs:
        /* Register usage:
         *
-        * a0 - relocation addend
+        * a0 - current relocation record pointer
         * a1 - current relocation target address
-        * a2 - current relocation record pointer
+        * a2 - relocation addend
         * a3 - current relocation record value
         * a4 - number of bits remaining in current relocation record
         */
        la      a1, _prefix
-       la      a2, _edata
 
        /* Calculate relocation addend */
-       LOADN   a0, prefix_virt
-       sub     a0, a1, a0
+       LOADN   a2, prefix_virt
+       sub     a2, a1, a2
 
        /* Skip applying relocations if addend is zero */
-       beqz    a0, apply_relocs_done
+       beqz    a2, apply_relocs_done
        progress " reloc"
 
 apply_relocs_loop:
        /* Read new relocation record */
-       LOADN   a3, (a2)
-       addi    a2, a2, ( __riscv_xlen / 8 )
+       LOADN   a3, (a0)
+       addi    a0, a0, ( __riscv_xlen / 8 )
        li      a4, ( __riscv_xlen - 1 )
 
        /* Consume and apply skip, if present (i.e. if MSB=0) */
@@ -275,7 +276,7 @@ apply_relocs_loop:
 1:     andi    t0, a3, 1
        beqz    t0, 2f
        LOADN   t1, (a1)
-       add     t1, t1, a0
+       add     t1, t1, a2
        STOREN  t1, (a1)
 2:     addi    a1, a1, ( __riscv_xlen / 8 )
        srli    a3, a3, 1

diff --git a/src/arch/riscv/prefix/sbiprefix.S b/src/arch/riscv/prefix/sbiprefix.S
index 3885c77be3cdf177deca5c324daf0ee427c8db61..e831676025346d0d7f137d56d484322b2e52ac1d 100644 (file)
--- a/src/arch/riscv/prefix/sbiprefix.S
+++ b/src/arch/riscv/prefix/sbiprefix.S
@@ -66,6 +66,7 @@ _sbi_start:
        progress "\nSBI->iPXE"
 
        /* Apply dynamic relocations */
+       la      a0, _edata
        call    apply_relocs
        progress " .reloc"