From b8464f22ff3c7768c6cc47d2b7d80c2efff4dd4a Mon Sep 17 00:00:00 2001
From: Jacob Lifshay <programmerjake@gmail.com>
Date: Thu, 7 Dec 2023 00:53:20 -0800
Subject: [PATCH] MemMMap: fix brk_syscall -- use unrounded input address as
 heap end

it should use the input address as given when tracking the end of
the heap and returning addresses. it still needs to align addresses
when mapping/unmapping pages.
---
 src/openpower/decoder/isa/mem.py | 21 ++++++++++++---------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/src/openpower/decoder/isa/mem.py b/src/openpower/decoder/isa/mem.py
index 64e5125a..3830ccae 100644
--- a/src/openpower/decoder/isa/mem.py
+++ b/src/openpower/decoder/isa/mem.py
@@ -583,8 +583,6 @@ class MemMMap(MemCommon):
             raise ValueError("heap_range is not a suitable range")
         if value.start % MMAP_PAGE_SIZE != 0:
             raise ValueError("heap_range.start must be aligned")
-        if value.stop % MMAP_PAGE_SIZE != 0:
-            raise ValueError("heap_range.stop must be aligned")
         self.__heap_range = value
 
     @staticmethod
@@ -766,9 +764,14 @@ class MemMMap(MemCommon):
             # can't shrink heap to negative size
             return self.heap_range.stop  # don't change heap
 
+        unaligned_addr = addr
+
         # round addr up to the nearest page
-        addr_div_page_size = -(-addr // MMAP_PAGE_SIZE)  # ceil(addr / size)
-        addr = addr_div_page_size * MMAP_PAGE_SIZE
+        addr = (addr + MMAP_PAGE_SIZE - 1) & ~(MMAP_PAGE_SIZE - 1)
+
+        heap_stop = self.heap_range.stop
+        # round heap_stop up to the nearest page
+        heap_stop = (heap_stop + MMAP_PAGE_SIZE - 1) & ~(MMAP_PAGE_SIZE - 1)
 
         # something else could be mmap-ped in the middle of the heap,
         # be careful...
@@ -780,7 +783,7 @@ class MemMMap(MemCommon):
                 # if the heap was split.
                 # the heap must not be a file mapping.
                 # the heap must not be shared, and must be RW
-                if b.addrs.stop == self.heap_range.stop and b.file is None \
+                if b.addrs.stop == heap_stop and b.file is None \
                         and b.flags == MMapPageFlags.RW:
                     block = b
                     break
@@ -794,10 +797,10 @@ class MemMMap(MemCommon):
             # unmap heap block
             if self.__mmap_emu_unmap(block) < 0:
                 block = None  # can't unmap heap block
-        elif addr > self.heap_range.stop and block is None:
+        elif addr > heap_stop and block is None:
             # map new heap block
             try:
-                addrs = range(self.heap_range.stop, addr)
+                addrs = range(heap_stop, addr)
                 block = MMapEmuBlock(addrs, flags=MMapPageFlags.RW)
                 if not self.__mmap_emu_map_fixed(block,
                                                  replace=False, dry_run=True):
@@ -823,8 +826,8 @@ class MemMMap(MemCommon):
             return self.heap_range.stop  # don't change heap
 
         # success! assign new heap_range
-        self.heap_range = range(self.heap_range.start, addr)
-        return self.heap_range.stop  # return new brk address
+        self.heap_range = range(self.heap_range.start, unaligned_addr)
+        return unaligned_addr  # return new brk address
 
     def mmap_syscall(self, addr, length, prot, flags, fd, offset, is_mmap2):
         assert self.emulating_mmap, "mmap syscall requires emulating_mmap=True"
-- 
2.30.2