From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Daniel Axtens <dja@axtens.net>
Date: Wed, 14 Apr 2021 20:10:23 +1000
Subject: [PATCH] ieee1275: drop HEAP_MAX_ADDR, HEAP_MIN_SIZE

HEAP_MAX_ADDR is confusing. Currently it is set to 32MB, except
on ieee1275 on x86, where it is 64MB.

There is a comment which purports to explain it:

/* If possible, we will avoid claiming heap above this address, because it
   seems to cause relocation problems with OSes that link at 4 MiB */

This doesn't make a lot of sense when the constants are well above 4MB
already. It was not always this way. Prior to
commit 7b5d0fe4440c ("Increase heap limit") in 2010, HEAP_MAX_SIZE and
HEAP_MAX_ADDR were indeed 4MB. However, when the constants were increased
the comment was left unchanged.

It's been over a decade. It doesn't seem like we have problems with
claims over 4MB on powerpc or x86 ieee1275. (sparc does things completely
differently and never used the constant.)

Drop the constant and the check.

The only use of HEAP_MIN_SIZE was to potentially override the
HEAP_MAX_ADDR check. It is now unused. Remove it.

Signed-off-by: Daniel Axtens <dja@axtens.net>
---
 grub-core/kern/ieee1275/init.c | 17 -----------------
 1 file changed, 17 deletions(-)

diff --git a/grub-core/kern/ieee1275/init.c b/grub-core/kern/ieee1275/init.c
index 22dc3013d86..ee97d761d1e 100644
--- a/grub-core/kern/ieee1275/init.c
+++ b/grub-core/kern/ieee1275/init.c
@@ -42,9 +42,6 @@
 #include <grub/machine/kernel.h>
 #endif
 
-/* The minimal heap size we can live with. */
-#define HEAP_MIN_SIZE		(unsigned long) (2 * 1024 * 1024)
-
 /* The maximum heap size we're going to claim */
 #ifdef __i386__
 #define HEAP_MAX_SIZE		(unsigned long) (64 * 1024 * 1024)
@@ -52,14 +49,6 @@
 #define HEAP_MAX_SIZE		(unsigned long) (32 * 1024 * 1024)
 #endif
 
-/* If possible, we will avoid claiming heap above this address, because it
-   seems to cause relocation problems with OSes that link at 4 MiB */
-#ifdef __i386__
-#define HEAP_MAX_ADDR		(unsigned long) (64 * 1024 * 1024)
-#else
-#define HEAP_MAX_ADDR		(unsigned long) (32 * 1024 * 1024)
-#endif
-
 extern char _end[];
 
 #ifdef __sparc__
@@ -181,12 +170,6 @@ heap_init (grub_uint64_t addr, grub_uint64_t len, grub_memory_type_t type,
   if (*total + len > HEAP_MAX_SIZE)
     len = HEAP_MAX_SIZE - *total;
 
-  /* Avoid claiming anything above HEAP_MAX_ADDR, if possible. */
-  if ((addr < HEAP_MAX_ADDR) &&				/* if it's too late, don't bother */
-      (addr + len > HEAP_MAX_ADDR) &&				/* if it wasn't available anyway, don't bother */
-      (*total + (HEAP_MAX_ADDR - addr) > HEAP_MIN_SIZE))	/* only limit ourselves when we can afford to */
-     len = HEAP_MAX_ADDR - addr;
-
   /* In theory, firmware should already prevent this from happening by not
      listing our own image in /memory/available.  The check below is intended
      as a safeguard in case that doesn't happen.  However, it doesn't protect
