On 06/09/16 10:26, BALATON Zoltan wrote:
On Mon, 5 Sep 2016, Mark Cave-Ayland wrote:
load should place the file at load-base, whilst init-program should parse the memory at load-base and set up the context accordingly.
Signed-off-by: Mark Cave-Ayland mark.cave-ayland@ilande.co.uk
libopenbios/aout_load.c | 44 +++++++++++++++++++++++--------------------- libopenbios/load.c | 15 ++++++++------- 2 files changed, 31 insertions(+), 28 deletions(-)
diff --git a/libopenbios/aout_load.c b/libopenbios/aout_load.c index 2433106..4dc9ac3 100644 --- a/libopenbios/aout_load.c +++ b/libopenbios/aout_load.c @@ -10,15 +10,10 @@ #define CONFIG_SPARC64_PAGE_SIZE_8KB #endif
-/* NextStep bootloader on SPARC32 expects the a.out header directly
- below load-base (0x4000) */
-#ifdef CONFIG_SPARC32 -#define AOUT_HEADER_COPY -#endif
#include "libopenbios/sys_info.h" #include "libopenbios/bindings.h" #include "libopenbios/aout_load.h" +#include "libopenbios/initprogram.h" #include "libc/diskio.h" #define printf printk #define debug printk @@ -85,7 +80,7 @@ aout_load(struct sys_info *info, ihandle_t dev)
/* Mark the saved-program-state as invalid */ feval("0 state-valid !");
- fd = open_ih(dev); if (fd == -1) { goto out;
@@ -123,15 +118,16 @@ aout_load(struct sys_info *info, ihandle_t dev) fword("load-base"); start = POP(); // N_TXTADDR(ehdr);
memcpy((void *)start, &ehdr, sizeof(ehdr));
if (!check_mem_ranges(info, start, size)) goto out;
printf("Loading a.out %s...\n", image_name ? image_name : "image");
seek_io(fd, offset + N_TXTOFF(ehdr));
if (N_MAGIC(ehdr) == NMAGIC) {
if ((size_t)read_io(fd, (void *)start, ehdr.a_text) !=ehdr.a_text) {
if ((size_t)read_io(fd, (void *)(start + N_TXTOFF(ehdr)),ehdr.a_text) != ehdr.a_text) { printf("Can't read program text segment (size 0x" FMT_aout_ehdr ")\n", ehdr.a_text); goto out; } @@ -140,7 +136,7 @@ aout_load(struct sys_info *info, ihandle_t dev) goto out; } } else {
if ((size_t)read_io(fd, (void *)start, size) != size) {
if ((size_t)read_io(fd, (void *)(start + N_TXTOFF(ehdr)),size) != size) { printf("Can't read program (size 0x" FMT_sizet ")\n", size); goto out; } @@ -149,20 +145,11 @@ aout_load(struct sys_info *info, ihandle_t dev) debug("Loaded %lu bytes\n", size); debug("entry point is %#lx\n", start);
-#ifdef AOUT_HEADER_COPY
- // Copy the a.out header just before start
- memcpy((char *)(start - 0x20), &ehdr, 0x20);
-#endif
// Initialise saved-program-state
PUSH(addr_fixup(start));
feval("load-state >ls.entry !"); PUSH(size); feval("load-state >ls.file-size !"); feval("aout load-state >ls.file-type !");
feval("-1 state-valid !");
out: close_io(fd); return retval; @@ -171,6 +158,21 @@ out: void aout_init_program(void) {
- // Currently not implemented
- feval("0 state-valid !");
- ucell start, size;
- // Relocate a.out text down from load-base to load-base - header.
This
- // is similar to what OBP and is needed for NextStep.
- fword("load-base");
- start = POP();
- feval("load-state >ls.file-size @");
- size = POP();
- memcpy((char *)start - sizeof(struct exec), (char *)start, size);
Shouldn't this be memmove() to handle overlapping regions correctly? (I assume size is often bigger than sizeof(struct exec).) Maybe it works with the current memcpy implementation in OpenBIOS but in case it's ever replaced memmove may be better.
I'm not sure that would have an effect here, since the copy in memory is always downwards from higher memory locations to lower memory locations (and I can't see how anyone would implement memcpy() backwards as it would be extremely cache unfriendly). But feel free to point out sources that suggest otherwise :)
My guess is this is an artifact from the first Sun PROMs which executed binary code directly, so when a.out came along they simply shifted the code back down over the header to maintain compatibility.
ATB,
Mark.