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winedbg/gdbproxy: Replace memory read over a breakpoint with the real value. 

Normally, when we hit a breakpoint, we remove it before stopping and add it
after continuing. gdb, however, reads the process memory before requesting
that the breakpoint be removed, and apparently caches it until the `stepi`
instruction is executed; as a result, it thinks that the interrupt byte that
is present in the code is an actual interrupt and not a breakpoint, and so
tries to step over it as one byte instead of executing the real instruction
at that location.

Signed-off-by: Zebediah Figura <z.figura12@gmail.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>
This commit is contained in:
Zebediah Figura 2018-01-14 19:01:15 -06:00 committed by Alexandre Julliard
parent d1e9694eda
commit eb63a5f3c3
1 changed files with 23 additions and 2 deletions
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25
programs/winedbg/gdbproxy.c
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@ -1568,6 +1568,28 @@ static enum packet_return packet_thread(struct gdb_context* gdbctx)
}
}
static BOOL read_memory(struct gdb_context *gdbctx, char *addr, char *buffer, SIZE_T blk_len, SIZE_T *r)
{
/* Wrapper around process_io->read() that replaces values displaced by breakpoints. */
BOOL ret;
ret = gdbctx->process->process_io->read(gdbctx->process->handle, addr, buffer, blk_len, r);
if (ret)
{
struct gdb_ctx_Xpoint *xpt;
for (xpt = &gdbctx->Xpoints[NUM_XPOINT - 1]; xpt >= gdbctx->Xpoints; xpt--)
{
char *xpt_addr = xpt->addr;
if (xpt->type != -1 && xpt_addr >= addr && xpt_addr < addr + blk_len)
buffer[xpt_addr - addr] = xpt->val;
}
}
return ret;
}
static enum packet_return packet_read_memory(struct gdb_context* gdbctx)
{
char *addr;
@ -1584,8 +1606,7 @@ static enum packet_return packet_read_memory(struct gdb_context* gdbctx)
for (nread = 0; nread < len; nread += r, addr += r)
{
blk_len = min(sizeof(buffer), len - nread);
if (!gdbctx->process->process_io->read(gdbctx->process->handle, addr, buffer, blk_len, &r) ||
r == 0)
if (!read_memory(gdbctx, addr, buffer, blk_len, &r) || r == 0)
{
/* fail at first address, return error */
if (nread == 0) return packet_reply_error(gdbctx, EFAULT);