MIPS: DEC/SNI: O32 wrapper stack switching fixes

Commit 231a35d37293ab88d325a9cb94e5474c156282c0 [[MIPS] RM: Collected
changes] broke DECstation support by introducing an incompatible copy of
arch/mips/dec/prom/call_o32.S in arch/mips/fw/lib/, built unconditionally.
The copy happens to land earlier of the two among the modules used in the
link and is therefore chosen for the DECstation rather than the intended
original.  As a result random kernel data is corrupted because a pointer
to the "%s" formatted output template is used as a temporary stack pointer
rather than being passed down to prom_printf.  This also explains why
prom_printf still works, up to a point -- the next argument is the actual
string to output so it works just fine as the output template until enough
kernel data has been corrupted to cause a crash.

This change adjusts the modified wrapper in arch/mips/fw/lib/call_o32.S to
let callers request no stack switching by passing a null temporary stack
pointer in $a1, reworks the DECstation callers to work with the updated
interface and removes the old copy from arch/mips/dec/prom/call_o32.S.  A
few minor readability adjustments are included as well, most importantly
O32_SZREG is now used throughout where applicable rather than hardcoded
multiplies of 4 and $fp is used to access the argument save area as a more
usual register to operate the stack with rather than $s0.

Finally an update is made to the temporary stack space used by the SNI
platform to guarantee 8-byte alignment as per o32 requirements.

Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6668/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 24 insertions, 24 deletions

diff --git a/arch/mips/include/asm/dec/prom.h b/arch/mips/include/asm/dec/prom.h
index c0ead6313845..b59a2103b61a 100644
--- a/arch/mips/include/asm/dec/prom.h
+++ b/arch/mips/include/asm/dec/prom.h
@@ -113,31 +113,31 @@ extern int (*__pmax_close)(int);
 #define __DEC_PROM_O32(fun, arg) fun arg __asm__(#fun); \
 				 __asm__(#fun " = call_o32")
 
-int __DEC_PROM_O32(_rex_bootinit, (int (*)(void)));
-int __DEC_PROM_O32(_rex_bootread, (int (*)(void)));
-int __DEC_PROM_O32(_rex_getbitmap, (int (*)(memmap *), memmap *));
+int __DEC_PROM_O32(_rex_bootinit, (int (*)(void), void *));
+int __DEC_PROM_O32(_rex_bootread, (int (*)(void), void *));
+int __DEC_PROM_O32(_rex_getbitmap, (int (*)(memmap *), void *, memmap *));
 unsigned long *__DEC_PROM_O32(_rex_slot_address,
-			     (unsigned long *(*)(int), int));
-void *__DEC_PROM_O32(_rex_gettcinfo, (void *(*)(void)));
-int __DEC_PROM_O32(_rex_getsysid, (int (*)(void)));
-void __DEC_PROM_O32(_rex_clear_cache, (void (*)(void)));
-
-int __DEC_PROM_O32(_prom_getchar, (int (*)(void)));
-char *__DEC_PROM_O32(_prom_getenv, (char *(*)(char *), char *));
-int __DEC_PROM_O32(_prom_printf, (int (*)(char *, ...), char *, ...));
-
-
-#define rex_bootinit()		_rex_bootinit(__rex_bootinit)
-#define rex_bootread()		_rex_bootread(__rex_bootread)
-#define rex_getbitmap(x)	_rex_getbitmap(__rex_getbitmap, x)
-#define rex_slot_address(x)	_rex_slot_address(__rex_slot_address, x)
-#define rex_gettcinfo()		_rex_gettcinfo(__rex_gettcinfo)
-#define rex_getsysid()		_rex_getsysid(__rex_getsysid)
-#define rex_clear_cache()	_rex_clear_cache(__rex_clear_cache)
-
-#define prom_getchar()		_prom_getchar(__prom_getchar)
-#define prom_getenv(x)		_prom_getenv(__prom_getenv, x)
-#define prom_printf(x...)	_prom_printf(__prom_printf, x)
+			     (unsigned long *(*)(int), void *, int));
+void *__DEC_PROM_O32(_rex_gettcinfo, (void *(*)(void), void *));
+int __DEC_PROM_O32(_rex_getsysid, (int (*)(void), void *));
+void __DEC_PROM_O32(_rex_clear_cache, (void (*)(void), void *));
+
+int __DEC_PROM_O32(_prom_getchar, (int (*)(void), void *));
+char *__DEC_PROM_O32(_prom_getenv, (char *(*)(char *), void *, char *));
+int __DEC_PROM_O32(_prom_printf, (int (*)(char *, ...), void *, char *, ...));
+
+
+#define rex_bootinit()		_rex_bootinit(__rex_bootinit, NULL)
+#define rex_bootread()		_rex_bootread(__rex_bootread, NULL)
+#define rex_getbitmap(x)	_rex_getbitmap(__rex_getbitmap, NULL, x)
+#define rex_slot_address(x)	_rex_slot_address(__rex_slot_address, NULL, x)
+#define rex_gettcinfo()		_rex_gettcinfo(__rex_gettcinfo, NULL)
+#define rex_getsysid()		_rex_getsysid(__rex_getsysid, NULL)
+#define rex_clear_cache()	_rex_clear_cache(__rex_clear_cache, NULL)
+
+#define prom_getchar()		_prom_getchar(__prom_getchar, NULL)
+#define prom_getenv(x)		_prom_getenv(__prom_getenv, NULL, x)
+#define prom_printf(x...)	_prom_printf(__prom_printf, NULL, x)
 
 #else /* !CONFIG_64BIT */