self-modifying code support
git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@163 c046a42c-6fe2-441c-8c8c-71466251a162
diff --git a/exec.c b/exec.c
index a917143..0ed49c6 100644
--- a/exec.c
+++ b/exec.c
@@ -1,5 +1,5 @@
/*
- * virtual page mapping
+ * virtual page mapping and translated block handling
*
* Copyright (c) 2003 Fabrice Bellard
*
@@ -24,13 +24,32 @@
#include <errno.h>
#include <unistd.h>
#include <inttypes.h>
+#include <sys/mman.h>
#include "cpu-i386.h"
+//#define DEBUG_TB_INVALIDATE
+#define DEBUG_FLUSH
+
+/* make various TB consistency checks */
+//#define DEBUG_TB_CHECK
+
+/* threshold to flush the translated code buffer */
+#define CODE_GEN_BUFFER_MAX_SIZE (CODE_GEN_BUFFER_SIZE - CODE_GEN_MAX_SIZE)
+
+#define CODE_GEN_MAX_BLOCKS (CODE_GEN_BUFFER_SIZE / 64)
+
+TranslationBlock tbs[CODE_GEN_MAX_BLOCKS];
+TranslationBlock *tb_hash[CODE_GEN_HASH_SIZE];
+int nb_tbs;
+
+uint8_t code_gen_buffer[CODE_GEN_BUFFER_SIZE];
+uint8_t *code_gen_ptr;
+
/* XXX: pack the flags in the low bits of the pointer ? */
typedef struct PageDesc {
- struct TranslationBlock *first_tb;
unsigned long flags;
+ TranslationBlock *first_tb;
} PageDesc;
#define L2_BITS 10
@@ -39,6 +58,8 @@
#define L1_SIZE (1 << L1_BITS)
#define L2_SIZE (1 << L2_BITS)
+static void tb_invalidate_page(unsigned long address);
+
unsigned long real_host_page_size;
unsigned long host_page_bits;
unsigned long host_page_size;
@@ -104,36 +125,44 @@
}
}
-
-static inline PageDesc *page_find_alloc(unsigned long address)
+static inline PageDesc *page_find_alloc(unsigned int index)
{
- unsigned int index;
PageDesc **lp, *p;
- index = address >> TARGET_PAGE_BITS;
lp = &l1_map[index >> L2_BITS];
p = *lp;
if (!p) {
/* allocate if not found */
p = malloc(sizeof(PageDesc) * L2_SIZE);
- memset(p, 0, sizeof(sizeof(PageDesc) * L2_SIZE));
+ memset(p, 0, sizeof(PageDesc) * L2_SIZE);
*lp = p;
}
return p + (index & (L2_SIZE - 1));
}
-int page_get_flags(unsigned long address)
+static inline PageDesc *page_find(unsigned int index)
{
- unsigned int index;
PageDesc *p;
- index = address >> TARGET_PAGE_BITS;
p = l1_map[index >> L2_BITS];
if (!p)
return 0;
- return p[index & (L2_SIZE - 1)].flags;
+ return p + (index & (L2_SIZE - 1));
}
+int page_get_flags(unsigned long address)
+{
+ PageDesc *p;
+
+ p = page_find(address >> TARGET_PAGE_BITS);
+ if (!p)
+ return 0;
+ return p->flags;
+}
+
+/* modify the flags of a page and invalidate the code if
+ necessary. The flag PAGE_WRITE_ORG is positionned automatically
+ depending on PAGE_WRITE */
void page_set_flags(unsigned long start, unsigned long end, int flags)
{
PageDesc *p;
@@ -141,8 +170,268 @@
start = start & TARGET_PAGE_MASK;
end = TARGET_PAGE_ALIGN(end);
+ if (flags & PAGE_WRITE)
+ flags |= PAGE_WRITE_ORG;
for(addr = start; addr < end; addr += TARGET_PAGE_SIZE) {
- p = page_find_alloc(addr);
+ p = page_find_alloc(addr >> TARGET_PAGE_BITS);
+ /* if the write protection is set, then we invalidate the code
+ inside */
+ if (!(p->flags & PAGE_WRITE) &&
+ (flags & PAGE_WRITE) &&
+ p->first_tb) {
+ tb_invalidate_page(addr);
+ }
p->flags = flags;
}
}
+
+void cpu_x86_tblocks_init(void)
+{
+ if (!code_gen_ptr) {
+ code_gen_ptr = code_gen_buffer;
+ }
+}
+
+/* set to NULL all the 'first_tb' fields in all PageDescs */
+static void page_flush_tb(void)
+{
+ int i, j;
+ PageDesc *p;
+
+ for(i = 0; i < L1_SIZE; i++) {
+ p = l1_map[i];
+ if (p) {
+ for(j = 0; j < L2_SIZE; j++)
+ p[j].first_tb = NULL;
+ }
+ }
+}
+
+/* flush all the translation blocks */
+void tb_flush(void)
+{
+ int i;
+#ifdef DEBUG_FLUSH
+ printf("qemu: flush code_size=%d nb_tbs=%d avg_tb_size=%d\n",
+ code_gen_ptr - code_gen_buffer,
+ nb_tbs,
+ (code_gen_ptr - code_gen_buffer) / nb_tbs);
+#endif
+ nb_tbs = 0;
+ for(i = 0;i < CODE_GEN_HASH_SIZE; i++)
+ tb_hash[i] = NULL;
+ page_flush_tb();
+ code_gen_ptr = code_gen_buffer;
+ /* XXX: flush processor icache at this point */
+}
+
+#ifdef DEBUG_TB_CHECK
+
+static void tb_invalidate_check(unsigned long address)
+{
+ TranslationBlock *tb;
+ int i;
+ address &= TARGET_PAGE_MASK;
+ for(i = 0;i < CODE_GEN_HASH_SIZE; i++) {
+ for(tb = tb_hash[i]; tb != NULL; tb = tb->hash_next) {
+ if (!(address + TARGET_PAGE_SIZE <= tb->pc ||
+ address >= tb->pc + tb->size)) {
+ printf("ERROR invalidate: address=%08lx PC=%08lx size=%04x\n",
+ address, tb->pc, tb->size);
+ }
+ }
+ }
+}
+
+/* verify that all the pages have correct rights for code */
+static void tb_page_check(void)
+{
+ TranslationBlock *tb;
+ int i, flags1, flags2;
+
+ for(i = 0;i < CODE_GEN_HASH_SIZE; i++) {
+ for(tb = tb_hash[i]; tb != NULL; tb = tb->hash_next) {
+ flags1 = page_get_flags(tb->pc);
+ flags2 = page_get_flags(tb->pc + tb->size - 1);
+ if ((flags1 & PAGE_WRITE) || (flags2 & PAGE_WRITE)) {
+ printf("ERROR page flags: PC=%08lx size=%04x f1=%x f2=%x\n",
+ tb->pc, tb->size, flags1, flags2);
+ }
+ }
+ }
+}
+
+#endif
+
+/* invalidate one TB */
+static inline void tb_remove(TranslationBlock **ptb, TranslationBlock *tb,
+ int next_offset)
+{
+ TranslationBlock *tb1;
+ for(;;) {
+ tb1 = *ptb;
+ if (tb1 == tb) {
+ *ptb = *(TranslationBlock **)((char *)tb1 + next_offset);
+ break;
+ }
+ ptb = (TranslationBlock **)((char *)tb1 + next_offset);
+ }
+}
+
+static inline void tb_invalidate(TranslationBlock *tb, int parity)
+{
+ PageDesc *p;
+ unsigned int page_index1, page_index2;
+ unsigned int h;
+
+ /* remove the TB from the hash list */
+ h = tb_hash_func(tb->pc);
+ tb_remove(&tb_hash[h], tb,
+ offsetof(TranslationBlock, hash_next));
+ /* remove the TB from the page list */
+ page_index1 = tb->pc >> TARGET_PAGE_BITS;
+ if ((page_index1 & 1) == parity) {
+ p = page_find(page_index1);
+ tb_remove(&p->first_tb, tb,
+ offsetof(TranslationBlock, page_next[page_index1 & 1]));
+ }
+ page_index2 = (tb->pc + tb->size - 1) >> TARGET_PAGE_BITS;
+ if ((page_index2 & 1) == parity) {
+ p = page_find(page_index2);
+ tb_remove(&p->first_tb, tb,
+ offsetof(TranslationBlock, page_next[page_index2 & 1]));
+ }
+}
+
+/* invalidate all TBs which intersect with the target page starting at addr */
+static void tb_invalidate_page(unsigned long address)
+{
+ TranslationBlock *tb_next, *tb;
+ unsigned int page_index;
+ int parity1, parity2;
+ PageDesc *p;
+#ifdef DEBUG_TB_INVALIDATE
+ printf("tb_invalidate_page: %lx\n", address);
+#endif
+
+ page_index = address >> TARGET_PAGE_BITS;
+ p = page_find(page_index);
+ if (!p)
+ return;
+ tb = p->first_tb;
+ parity1 = page_index & 1;
+ parity2 = parity1 ^ 1;
+ while (tb != NULL) {
+ tb_next = tb->page_next[parity1];
+ tb_invalidate(tb, parity2);
+ tb = tb_next;
+ }
+ p->first_tb = NULL;
+}
+
+/* add the tb in the target page and protect it if necessary */
+static inline void tb_alloc_page(TranslationBlock *tb, unsigned int page_index)
+{
+ PageDesc *p;
+ unsigned long host_start, host_end, addr, page_addr;
+ int prot;
+
+ p = page_find_alloc(page_index);
+ tb->page_next[page_index & 1] = p->first_tb;
+ p->first_tb = tb;
+ if (p->flags & PAGE_WRITE) {
+ /* force the host page as non writable (writes will have a
+ page fault + mprotect overhead) */
+ page_addr = (page_index << TARGET_PAGE_BITS);
+ host_start = page_addr & host_page_mask;
+ host_end = host_start + host_page_size;
+ prot = 0;
+ for(addr = host_start; addr < host_end; addr += TARGET_PAGE_SIZE)
+ prot |= page_get_flags(addr);
+ mprotect((void *)host_start, host_page_size,
+ (prot & PAGE_BITS) & ~PAGE_WRITE);
+#ifdef DEBUG_TB_INVALIDATE
+ printf("protecting code page: 0x%08lx\n",
+ host_start);
+#endif
+ p->flags &= ~PAGE_WRITE;
+#ifdef DEBUG_TB_CHECK
+ tb_page_check();
+#endif
+ }
+}
+
+/* Allocate a new translation block. Flush the translation buffer if
+ too many translation blocks or too much generated code. */
+TranslationBlock *tb_alloc(unsigned long pc,
+ unsigned long size)
+{
+ TranslationBlock *tb;
+ unsigned int page_index1, page_index2;
+
+ if (nb_tbs >= CODE_GEN_MAX_BLOCKS ||
+ (code_gen_ptr - code_gen_buffer) >= CODE_GEN_BUFFER_MAX_SIZE)
+ tb_flush();
+ tb = &tbs[nb_tbs++];
+ tb->pc = pc;
+ tb->size = size;
+
+ /* add in the page list */
+ page_index1 = pc >> TARGET_PAGE_BITS;
+ tb_alloc_page(tb, page_index1);
+ page_index2 = (pc + size - 1) >> TARGET_PAGE_BITS;
+ if (page_index2 != page_index1) {
+ tb_alloc_page(tb, page_index2);
+ }
+ return tb;
+}
+
+/* called from signal handler: invalidate the code and unprotect the
+ page. Return TRUE if the fault was succesfully handled. */
+int page_unprotect(unsigned long address)
+{
+ unsigned int page_index, prot;
+ PageDesc *p;
+ unsigned long host_start, host_end, addr;
+
+ page_index = address >> TARGET_PAGE_BITS;
+ p = page_find(page_index);
+ if (!p)
+ return 0;
+ if ((p->flags & (PAGE_WRITE_ORG | PAGE_WRITE)) == PAGE_WRITE_ORG) {
+ /* if the page was really writable, then we change its
+ protection back to writable */
+ host_start = address & host_page_mask;
+ host_end = host_start + host_page_size;
+ prot = 0;
+ for(addr = host_start; addr < host_end; addr += TARGET_PAGE_SIZE)
+ prot |= page_get_flags(addr);
+ mprotect((void *)host_start, host_page_size,
+ (prot & PAGE_BITS) | PAGE_WRITE);
+ p->flags |= PAGE_WRITE;
+
+ /* and since the content will be modified, we must invalidate
+ the corresponding translated code. */
+ tb_invalidate_page(address);
+#ifdef DEBUG_TB_CHECK
+ tb_invalidate_check(address);
+#endif
+ return 1;
+ } else {
+ return 0;
+ }
+}
+
+/* call this function when system calls directly modify a memory area */
+void page_unprotect_range(uint8_t *data, unsigned long data_size)
+{
+ unsigned long start, end, addr;
+
+ start = (unsigned long)data;
+ end = start + data_size;
+ start &= TARGET_PAGE_MASK;
+ end = TARGET_PAGE_ALIGN(end);
+ for(addr = start; addr < end; addr += TARGET_PAGE_SIZE) {
+ page_unprotect(addr);
+ }
+}
