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ARM: semihosting entry cleanup 

Clean up arm_semihosting() entry a bit, comment some issues and just
which SVC opcodes are getting intercepted.  Microcontroller profile
cores will need a new entry, since they use BKPT instead (and don't
have either SVC mode or an SPSR register).

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
This commit is contained in:
David Brownell 2009-12-04 16:51:48 -08:00
parent bdde9460b9
commit 32f961daba
1 changed files with 39 additions and 8 deletions
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47
src/target/arm_semihosting.c
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@ -56,6 +56,9 @@ static int do_semihosting(struct target *target)
* - no validation on target provided file descriptors
* - no safety checks on opened/deleted/renamed file paths
* Beware the target app you use this support with.
*
* TODO: explore mapping requests to GDB's "File-I/O Remote
* Protocol Extension" ... when GDB is active.
*/
switch (r0) {
case 0x01: /* SYS_OPEN */
@ -396,42 +399,70 @@ static int do_semihosting(struct target *target)
* or an error was encountered, in which case the caller must return
* immediately.
*
* @param target Pointer to the ARM target to process
* @param target Pointer to the ARM target to process. This target must
* not represent an ARMv6-M or ARMv7-M processor.
* @param retval Pointer to a location where the return code will be stored
* @return non-zero value if a request was processed or an error encountered
*/
int arm_semihosting(struct target *target, int *retval)
{
struct arm *armv4_5 = target_to_armv4_5(target);
struct arm *arm = target_to_armv4_5(target);
uint32_t lr, spsr;
struct reg *r;
if (!armv4_5->is_semihosting ||
armv4_5->core_mode != ARMV4_5_MODE_SVC ||
buf_get_u32(armv4_5->core_cache->reg_list[15].value, 0, 32) != 0x08)
if (!arm->is_semihosting || arm->core_mode != ARMV4_5_MODE_SVC)
return 0;
lr = buf_get_u32(ARMV4_5_CORE_REG_MODE(armv4_5->core_cache, ARMV4_5_MODE_SVC, 14).value, 0, 32);
spsr = buf_get_u32(armv4_5->spsr->value, 0, 32);
/* Check for PC == 8: Supervisor Call vector
* REVISIT: assumes low exception vectors, not hivecs...
* safer to test "was this entry from a vector catch".
*/
r = arm->core_cache->reg_list + 15;
if (buf_get_u32(r->value, 0, 32) != 0x08)
return 0;
r = arm_reg_current(arm, 14);
lr = buf_get_u32(r->value, 0, 32);
/* Core-specific code should make sure SPSR is retrieved
* when the above checks pass...
*/
if (!arm->spsr->valid) {
LOG_ERROR("SPSR not valid!");
*retval = ERROR_FAIL;
return 1;
}
spsr = buf_get_u32(arm->spsr->value, 0, 32);
/* check instruction that triggered this trap */
if (spsr & (1 << 5)) {
/* was in Thumb mode */
/* was in Thumb (or ThumbEE) mode */
uint8_t insn_buf[2];
uint16_t insn;
*retval = target_read_memory(target, lr-2, 2, 1, insn_buf);
if (*retval != ERROR_OK)
return 1;
insn = target_buffer_get_u16(target, insn_buf);
/* SVC 0xab */
if (insn != 0xDFAB)
return 0;
} else if (spsr & (1 << 24)) {
/* was in Jazelle mode */
return 0;
} else {
/* was in ARM mode */
uint8_t insn_buf[4];
uint32_t insn;
*retval = target_read_memory(target, lr-4, 4, 1, insn_buf);
if (*retval != ERROR_OK)
return 1;
insn = target_buffer_get_u32(target, insn_buf);
/* SVC 0x123456 */
if (insn != 0xEF123456)
return 0;
}