[OpenBIOS] [PATCH, RFC 4/6] ppc: Move malloc zone

[Andreas Färber]

ofmem was fixed at 0x05400000, followed by the malloc zone.
The latter was bounded by the stack, relative to the top of RAM.
An increase of RAM would therefore only enlarge the malloc zone.

Move the malloc zone below the stack, with a fixed size of 2 MiB.
The size is derived from the memory map depicted in ofmem.c;
having a fixed size leaves room for memory claim'ed by clients
and by OpenBIOS.

Cc: Alexander Graf <agraf at suse.de>
Signed-off-by: Andreas Färber <andreas.faerber at web.de>
---
 arch/ppc/qemu/ofmem.c |   19 +++++++++----------
 arch/ppc/qemu/start.S |    4 ++++
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/arch/ppc/qemu/ofmem.c b/arch/ppc/qemu/ofmem.c
index 500752b..711ed01 100644
--- a/arch/ppc/qemu/ofmem.c
+++ b/arch/ppc/qemu/ofmem.c
@@ -47,11 +47,9 @@ extern void setup_mmu( unsigned long code_base );
 #define FREE_BASE		0x00004000
 #define OF_CODE_START	0xfff00000UL
 #define IO_BASE			0x80000000
-#define OFMEM			((ofmem_t*)0x05400000)
-
-#define OF_MALLOC_BASE		((char*)OFMEM + ((sizeof(ofmem_t) + 3) & ~3))
 
 #define HASH_SIZE		(2 << 15)
+#define OFMEM_SIZE		(2 * 1024 * 1024)
 
 #define	SEGR_USER		BIT(2)
 #define SEGR_BASE		0x0400
@@ -86,7 +84,7 @@ get_rom_base( void )
 unsigned long
 get_ram_top( void )
 {
-	return get_hash_base() - (32 + 64 + 64) * 1024;
+	return get_hash_base() - (32 + 64 + 64) * 1024 - OFMEM_SIZE;
 }
 
 unsigned long
@@ -107,12 +105,12 @@ static inline size_t ALIGN_SIZE(size_t x, size_t a)
 
 ofmem_t* ofmem_arch_get_private(void)
 {
-	return OFMEM;
+	return (ofmem_t*)(get_heap_top() - OFMEM_SIZE);
 }
 
 void* ofmem_arch_get_malloc_base(void)
 {
-	return OF_MALLOC_BASE;
+	return (char*)ofmem_arch_get_private() + ALIGN_SIZE(sizeof(ofmem_t), 4);
 }
 
 ucell ofmem_arch_get_heap_top(void)
@@ -388,15 +386,12 @@ isi_exception( void )
 void
 setup_mmu( unsigned long ramsize )
 {
-	ofmem_t *ofmem = OFMEM;
+	ofmem_t *ofmem;
 	unsigned long sdr1, sr_base, msr;
 	unsigned long hash_base;
 	unsigned long hash_mask = 0xffff0000;
 	int i;
 
-	memset(ofmem, 0, sizeof(ofmem_t));
-	ofmem->ramsize = ramsize;
-
 	/* SDR1: Storage Description Register 1 */
 
 	if(is_ppc64())
@@ -415,6 +410,10 @@ setup_mmu( unsigned long ramsize )
 		asm volatile("mtsrin %0,%1" :: "r" (sr_base + i), "r" (j) );
 	}
 
+	ofmem = ofmem_arch_get_private();
+	memset(ofmem, 0, sizeof(ofmem_t));
+	ofmem->ramsize = ramsize;
+
 	memcpy((void *)get_rom_base(), (void *)OF_CODE_START, 0x00100000);
 
 	/* Enable MMU */
diff --git a/arch/ppc/qemu/start.S b/arch/ppc/qemu/start.S
index d74fb9c..9417098 100644
--- a/arch/ppc/qemu/start.S
+++ b/arch/ppc/qemu/start.S
@@ -321,6 +321,10 @@ GLOBL(_entry):
 	 *     |                         |
 	 *     +-------------------------+
 	 *     |                         |
+	 *     | Malloc Zone (2 MiB)     |
+	 *     |                         |
+	 *     +-------------------------+
+	 *     |                         |
 	 *     | Client Stack (64 kB)    |
 	 *     |                         |
 	 *     +-------------------------+
-- 
1.7.3