[SLOF] [PATCH v3] boot: do not use catpad to concatenate strings

[Nikunj A Dadhania]

The catpad size is 1K size, which can be hit easily hit with around 20 devices
with bootindex.

Open code EVALUATE such that concatenation is not required. Replace usage of
$cat with a dynamically allocated buffer(16K) here.

Reported here: https://github.com/qemu/SLOF/issues/3

Signed-off-by: Nikunj A Dadhania <nikunj at linux.vnet.ibm.com>

---

qemu-system-ppc64 -nographic -nodefaults -serial stdio -monitor pty -m 2G \
-device virtio-scsi-pci    \
`for ((i=2;i<=50;i++)) ; \
do echo -n "  -drive file=/tmp/storage$i.qcow2,if=none,id=drive$i,format=qcow2 \
-device
scsi-hd,drive=drive$i,id=disk$i,channel=0,scsi-id=0,lun=$i,bootindex=$i"; \
done;` \
-drive file=guest.disk,if=none,id=drv1,format=qcow2,cache=none \
-device scsi-hd,drive=drv1,bootindex=1 -boot menu=on,splash-time=3000,strict=on
---
 slof/fs/boot.fs | 53 ++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 48 insertions(+), 5 deletions(-)

diff --git a/slof/fs/boot.fs b/slof/fs/boot.fs
index 1fd7439..6d16c54 100644
--- a/slof/fs/boot.fs
+++ b/slof/fs/boot.fs
@@ -15,8 +15,27 @@
 VARIABLE state-valid false state-valid !
 CREATE go-args 2 cells allot go-args 2 cells erase
 
+4000 CONSTANT bootdev-size
+0 VALUE bootdev-buf
+
 \ \\\\\\\\\\\\\\ Structure/Implementation Dependent Methods
 
+: alloc-bootdev-buf ( -- )
+   bootdev-size alloc-mem ?dup 0= ABORT" Unable to allocate bootdev buffer!"
+   dup bootdev-size erase
+   to bootdev-buf
+;
+
+: free-bootdev-buf ( -- )
+   bootdev-buf bootdev-size free-mem
+   0 to bootdev-buf
+;
+
+: bootdev-string-cat ( addr1 len1 addr2 len2 -- addr1 len1+len2 )
+   dup 3 pick + bootdev-size > ABORT" bootdev size too big!"
+   string-cat
+;
+
 : $bootargs
    bootargs 2@ ?dup IF
    ELSE s" diagnostic-mode?" evaluate and IF s" diag-file" evaluate
@@ -24,14 +43,23 @@ CREATE go-args 2 cells allot go-args 2 cells erase
 ;
 
 : $bootdev ( -- device-name len )
-   bootdevice 2@ dup IF s"  " $cat THEN
+   alloc-bootdev-buf
+   bootdevice 2@ ?dup IF
+      swap bootdev-buf 2 pick move
+      bootdev-buf swap s"  " bootdev-string-cat
+   ELSE
+      \ use bootdev-buf for concatenating diag mode/boot-device if any
+      drop bootdev-buf 0
+   THEN
    s" diagnostic-mode?" evaluate IF
       s" diag-device" evaluate
    ELSE
       s" boot-device" evaluate
    THEN
-   $cat \ prepend bootdevice setting from vpd-bootlist
+   ( bootdev len str len1 )
+   bootdev-string-cat \ concatenate both
    strdup
+   free-bootdev-buf
    ?dup 0= IF
       disable-watchdog
       drop true ABORT" No boot device!"
@@ -51,7 +79,14 @@ CREATE go-args 2 cells allot go-args 2 cells erase
 ' (set-boot-device) to set-boot-device
 
 : (add-boot-device) ( str len -- )	\ Concatenate " str" to "bootdevice"
-   bootdevice 2@ ?dup IF $cat-space ELSE drop THEN set-boot-device
+   bootdevice 2@ ?dup IF
+      alloc-bootdev-buf
+      swap bootdev-buf 2 pick move
+      bootdev-buf swap s"  " bootdev-string-cat
+      2swap bootdev-string-cat
+   ELSE drop THEN
+   set-boot-device
+   bootdev-buf 0 <> IF free-bootdev-buf THEN
 ;
 
 ' (add-boot-device) to add-boot-device
@@ -221,11 +256,19 @@ defer go ( -- )
    ELSE
       drop
    THEN
-   set-boot-args s" parse-load " $bootdev $cat strdup evaluate
+   set-boot-args
+   save-source  -1 to source-id
+   $bootdev dup #ib ! span ! to ib
+   0 >in !
+   ['] parse-load catch restore-source throw
 ;
 
 : load-next ( -- success )	\ Continue after go failed
-   load-list 2@ ?dup IF s" parse-load " 2swap $cat strdup evaluate
+   load-list 2@ ?dup IF
+      save-source  -1 to source-id
+      dup #ib ! span ! to ib
+      0 >in !
+      ['] parse-load catch restore-source throw
    ELSE drop false THEN
 ;
 
-- 
2.13.6