From aca421d0bbd021c4b0e320195692d9760d9ecdcd Mon Sep 17 00:00:00 2001 From: Paul Fertser Date: Sun, 14 Apr 2013 21:58:49 +0400 Subject: 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 --- src/gdb_main.c | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 70 insertions(+) (limited to 'src/gdb_main.c') diff --git a/src/gdb_main.c b/src/gdb_main.c index 6be6d0f..887b9ac 100644 --- a/src/gdb_main.c +++ b/src/gdb_main.c @@ -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. */ -- cgit v1.2.3