Message ID | 1336625347-10169-3-git-send-email-benh@kernel.crashing.org |
---|---|
State | New |
Headers | show |
On 05/09/2012 11:48 PM, Benjamin Herrenschmidt wrote: > From: David Gibson<david@gibson.dropbear.id.au> > > 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<david@gibson.dropbear.id.au> > Signed-off-by: Benjamin Herrenschmidt<benh@kernel.crashing.org> > --- > cpu-common.h | 1 + > exec.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ > 2 files changed, 54 insertions(+) > > 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 0607c9b..8511496 100644 > --- a/exec.c > +++ b/exec.c > @@ -3581,6 +3581,59 @@ 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) > +{ I'd think a memset() like interface would be better but... We should definitely implement this function in terms of cpu_physical_memory_write instead of open coding the logic again. Regards, Anthony Liguori > + int l; > + 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; > + addr1 = memory_region_section_addr(section, addr); > + /* 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(section->mr, addr1, 0, 4); > + l = 4; > + } else if (l>= 2&& ((addr1& 1) == 0)) { > + /* 16 bit write access */ > + io_mem_write(section->mr, addr1, 0, 2); > + l = 2; > + } else { > + /* 8 bit write access */ > + io_mem_write(section->mr, addr1, 0, 1); > + l = 1; > + } > + } else if (!section->readonly) { > + ram_addr_t addr1; > + addr1 = memory_region_get_ram_addr(section->mr) > + + memory_region_section_addr(section, addr); > + /* 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)
On Mon, May 14, 2012 at 07:42:00PM -0500, Anthony Liguori wrote: > On 05/09/2012 11:48 PM, Benjamin Herrenschmidt wrote: > >From: David Gibson<david@gibson.dropbear.id.au> [snip] > >@@ -3581,6 +3581,59 @@ 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) > >+{ > > I'd think a memset() like interface would be better but... I can work with that. > We should definitely implement this function in terms of > cpu_physical_memory_write instead of open coding the logic again. Hrm. Having solved merge conflicts several times by recopying the cpu_physical_memory_rw() logic, I can certainly see the attraction in that. However, the point of this function is *not* to have to allocate a temporary buffer, and I don't really see how to combine the logic without that.
On 05/14/2012 08:23 PM, David Gibson wrote: > On Mon, May 14, 2012 at 07:42:00PM -0500, Anthony Liguori wrote: >> On 05/09/2012 11:48 PM, Benjamin Herrenschmidt wrote: >>> From: David Gibson<david@gibson.dropbear.id.au> > [snip] >>> @@ -3581,6 +3581,59 @@ 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) >>> +{ >> >> I'd think a memset() like interface would be better but... > > I can work with that. > >> We should definitely implement this function in terms of >> cpu_physical_memory_write instead of open coding the logic again. > > Hrm. Having solved merge conflicts several times by recopying the > cpu_physical_memory_rw() logic, I can certainly see the attraction in > that. However, the point of this function is *not* to have to > allocate a temporary buffer, and I don't really see how to combine the > logic without that. Just use a fixed buffer (uint8_t buffer[512]) and call cpu_physical_memory_rw multiple times with an offset. Regards, Anthony Liguori >
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 0607c9b..8511496 100644 --- a/exec.c +++ b/exec.c @@ -3581,6 +3581,59 @@ 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; + 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; + addr1 = memory_region_section_addr(section, addr); + /* 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(section->mr, addr1, 0, 4); + l = 4; + } else if (l >= 2 && ((addr1 & 1) == 0)) { + /* 16 bit write access */ + io_mem_write(section->mr, addr1, 0, 2); + l = 2; + } else { + /* 8 bit write access */ + io_mem_write(section->mr, addr1, 0, 1); + l = 1; + } + } else if (!section->readonly) { + ram_addr_t addr1; + addr1 = memory_region_get_ram_addr(section->mr) + + memory_region_section_addr(section, addr); + /* 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)