motorhead/qemu
1
0
Fork 0
mirror of https://github.com/Motorhead1991/qemu.git synced 2025-08-03 07:43:54 -06:00
Code Issues Projects Releases Packages Wiki Activity Actions

tcg: Add extended GETPC mechanism for MMU helpers with ldst optimization

Browse source 
Add GETPC_EXT which is used by MMU helpers to selectively calculate the code
address of accessing guest memory when called from a qemu_ld/st optimized code
or a C function. Currently, it supports only i386 and x86-64 hosts.

Signed-off-by: Yeongkyoon Lee <yeongkyoon.lee@samsung.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This commit is contained in:
Yeongkyoon Lee 2012-10-31 16:04:24 +09:00 • committed by Blue Swirl
parent 32761257c0
commit fdbb84d133
3 changed files with 55 additions and 8 deletions
Download patch file Download diff file Expand all files Collapse all files

36
exec-all.h
View file

@ -310,6 +310,42 @@ extern uintptr_t tci_tb_ptr;
# define GETPC() ((uintptr_t)__builtin_return_address(0) - 1)
#endif
#if defined(CONFIG_QEMU_LDST_OPTIMIZATION) && defined(CONFIG_SOFTMMU)
/* qemu_ld/st optimization split code generation to fast and slow path, thus,
it needs special handling for an MMU helper which is called from the slow
path, to get the fast path's pc without any additional argument.
It uses a tricky solution which embeds the fast path pc into the slow path.
Code flow in slow path:
(1) pre-process
(2) call MMU helper
(3) jump to (5)
(4) fast path information (implementation specific)
(5) post-process (e.g. stack adjust)
(6) jump to corresponding code of the next of fast path
*/
# if defined(__i386__) || defined(__x86_64__)
/* To avoid broken disassembling, long jmp is used for embedding fast path pc,
so that the destination is the next code of fast path, though this jmp is
never executed.
call MMU helper
jmp POST_PROC (2byte) <- GETRA()
jmp NEXT_CODE (5byte)
POST_PROCESS ... <- GETRA() + 7
*/
# define GETRA() ((uintptr_t)__builtin_return_address(0))
# define GETPC_LDST() ((uintptr_t)(GETRA() + 7 + \
*(int32_t *)((void *)GETRA() + 3) - 1))
# else
# error "CONFIG_QEMU_LDST_OPTIMIZATION needs GETPC_LDST() implementation!"
# endif
bool is_tcg_gen_code(uintptr_t pc_ptr);
# define GETPC_EXT() (is_tcg_gen_code(GETRA()) ? GETPC_LDST() : GETPC())
#else
# define GETPC_EXT() GETPC()
#endif
#if !defined(CONFIG_USER_ONLY)
struct MemoryRegion *iotlb_to_region(hwaddr index);