sys64738
/
blackmagic
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Basic semihosting support 

Implement bare minimum necessary to support console IO.

This works with standard newlib builds and is based on the reference
documentation:
http://infocenter.arm.com/help/topic/com.arm.doc.dui0471c/CHDJHHDI.html

Tested using gcc-arm-none-eabi-4_7-2013q1-20130313 for both
stm32f1-based BMP and stm32f0 target.

Signed-off-by: Paul Fertser <fercerpav@gmail.com>
This commit is contained in:
Paul Fertser 2013-04-14 21:58:49 +04:00 committed by Gareth McMullin
parent feaf626673
commit aca421d0bb
2 changed files with 82 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
README
View File

@ -45,6 +45,18 @@ your '.gdbinit'. That will allow you to access addresses outside of
the memory map. It will treat anything outside of the memory map as
RAM.
Semihosting support
===================
Basic armv6m/armv7m semihosting is supported, i.e. you can build your
application in a special way to use host's stdin and stdout right
inside gdb simply by calling printf(), scanf() and other input-output
functions. To make use of it, add --specs=rdimon.specs and -lrdimon to
the linker flags for your firmware.
All writes are treated as writes to the stdout, all reads are done
from stdin; SYS_ISTTY always returns true, SYS_ERRNO -- EINTR;
SYS_OPEN and SYS_FLEN return dummy non-zero values.
Project layout
==============
driver/ - Windows drivers for the Black Magic probe hardware.

70
src/gdb_main.c
View File

@ -75,6 +75,8 @@ gdb_main(void)
{
int size;
bool single_step = false;
char last_activity = 0;
uint32_t semihost_read_bytes = 0;
DEBUG("Entring GDB protocol main loop\n");
/* GDB protocol main loop */
@ -82,6 +84,7 @@ gdb_main(void)
SET_IDLE_STATE(1);
size = gdb_getpacket(pbuf, BUF_SIZE);
SET_IDLE_STATE(0);
continue_activity:
switch(pbuf[0]) {
/* Implementation of these is mandatory! */
case 'g': { /* 'g': Read general registers */
@ -163,9 +166,48 @@ gdb_main(void)
unsigned char c = gdb_if_getchar_to(0);
if((c == '\x03') || (c == '\x04')) {
target_halt_request(cur_target);
last_activity = 's';
}
}
SET_RUN_STATE(0);
uint32_t arm_regs[cur_target->regs_size];
uint32_t semihost_buf[4];
target_regs_read(cur_target, arm_regs);
target_mem_read_bytes(cur_target, (uint8_t *)semihost_buf, arm_regs[15], 2);
/* Is this a semihosting breakpoint? */
if ((semihost_buf[0] & 0xFFFF) == 0xBEAB) {
last_activity = pbuf[0];
semihost_read_bytes = 0;
target_mem_read_words(cur_target, semihost_buf, arm_regs[1], sizeof(semihost_buf));
switch (arm_regs[0]) {
case 0x09: /* SYS_ISTTY */
arm_regs[0] = 1; /* it's a tty */
target_regs_write(cur_target, arm_regs);
/* fall-through */
case 0x01: /* SYS_OPEN */
case 0x0C: /* SYS_FLEN */
/* pretend it's successful, r0 is non-zero already */
goto continue_activity;
case 0x13: /* SYS_ERRNO */
arm_regs[0] = 4; /* EINTR */
target_regs_write(cur_target, arm_regs);
goto continue_activity;
case 0x05: /* SYS_WRITE */
gdb_putpacket_f("Fwrite,1,%08X,%08X",
semihost_buf[1], semihost_buf[2]);
arm_regs[0] = 0; /* pretend it's always successful */
target_regs_write(cur_target, arm_regs);
continue;
case 0x06: /* SYS_READ */
gdb_putpacket_f("Fread,0,%08X,%08X",
semihost_buf[1], semihost_buf[2]);
semihost_read_bytes = semihost_buf[2];
continue;
}
}
/* Report reason for halt */
if(target_check_hw_wp(cur_target, &watch_addr)) {
/* Watchpoint hit */
@ -175,6 +217,34 @@ gdb_main(void)
}
break;
}
case 'F': { /* Semihosting call finished */
int bytes, errcode, items;
char c, *p;
if (pbuf[1] == '-')
p = &pbuf[2];
else
p = &pbuf[1];
items = sscanf(p, "%x,%x,%c", &bytes, &errcode, &c);
if (semihost_read_bytes) {
uint32_t arm_regs[cur_target->regs_size];
target_regs_read(cur_target, arm_regs);
if (items == 3 && c == 'C')
arm_regs[0] = -1;
else
arm_regs[0] = semihost_read_bytes - bytes;
target_regs_write(cur_target, arm_regs);
}
/* if break is requested */
if (items == 3 && c == 'C') {
gdb_putpacketz("T02");
break;
}
pbuf[0] = last_activity;
goto continue_activity;
}
/* Optional GDB packet support */
case '!': /* Enable Extended GDB Protocol. */