This patch adds cpu_physical_memory_zero() function. This is equivalent to
calling cpu_physical_memory_write() with a buffer full of zeroes, but
avoids actually allocating such a buffer along the way.
Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
---
cpu-common.h | 1 +
exec.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 58 insertions(+), 0 deletions(-)
diff --git a/cpu-common.h b/cpu-common.h
index dca5175..146429c 100644
--- a/cpu-common.h
+++ b/cpu-common.h
@@ -53,6 +53,7 @@ void qemu_ram_set_idstr(ram_addr_t addr, const char *name,
DeviceState *dev);
void cpu_physical_memory_rw(target_phys_addr_t addr, uint8_t *buf,
int len, int is_write);
+void cpu_physical_memory_zero(target_phys_addr_t addr, int len);
static inline void cpu_physical_memory_read(target_phys_addr_t addr,
void *buf, int len)
{
diff --git a/exec.c b/exec.c
index a37d748..61d29bd 100644
--- a/exec.c
+++ b/exec.c
@@ -3914,6 +3914,63 @@ void cpu_physical_memory_rw(target_phys_addr_t addr,
uint8_t *buf,
}
}
+void cpu_physical_memory_zero(target_phys_addr_t addr, int len)
+{
+ int l, io_index;
+ uint8_t *ptr;
+ target_phys_addr_t page;
+ MemoryRegionSection section;
+
+ while (len > 0) {
+ page = addr & TARGET_PAGE_MASK;
+ l = (page + TARGET_PAGE_SIZE) - addr;
+ if (l > len)
+ l = len;
+ section = phys_page_find(page >> TARGET_PAGE_BITS);
+
+ if (!memory_region_is_ram(section.mr)) {
+ target_phys_addr_t addr1;
+ io_index = memory_region_get_ram_addr(section.mr)
+ & (IO_MEM_NB_ENTRIES - 1);
+ addr1 = (addr & ~TARGET_PAGE_MASK)
+ + section.offset_within_region;
+ /* XXX: could force cpu_single_env to NULL to avoid
+ potential bugs */
+ if (l >= 4 && ((addr1 & 3) == 0)) {
+ /* 32 bit write access */
+ io_mem_write(io_index, addr1, 0, 4);
+ l = 4;
+ } else if (l >= 2 && ((addr1 & 1) == 0)) {
+ /* 16 bit write access */
+ io_mem_write(io_index, addr1, 0, 2);
+ l = 2;
+ } else {
+ /* 8 bit write access */
+ io_mem_write(io_index, addr1, 0, 1);
+ l = 1;
+ }
+ } else if (!section.readonly) {
+ ram_addr_t addr1;
+ addr1 = (memory_region_get_ram_addr(section.mr)
+ + section.offset_within_region)
+ | (addr & ~TARGET_PAGE_MASK);
+ /* RAM case */
+ ptr = qemu_get_ram_ptr(addr1);
+ memset(ptr, 0, l);
+ if (!cpu_physical_memory_is_dirty(addr1)) {
+ /* invalidate code */
+ tb_invalidate_phys_page_range(addr1, addr1 + l, 0);
+ /* set dirty bit */
+ cpu_physical_memory_set_dirty_flags(
+ addr1, (0xff & ~CODE_DIRTY_FLAG));
+ }
+ qemu_put_ram_ptr(ptr);
+ }
+ len -= l;
+ addr += l;
+ }
+}
+
/* used for ROM loading : can write in RAM and ROM */
void cpu_physical_memory_write_rom(target_phys_addr_t addr,
const uint8_t *buf, int len)
--
1.7.9.1
