Possibly insecure! /* Terminal I/O operations */ SYS_WRITEC EQU 0x03 //Write one character to the debug terminal. Possibly insecure! SYS_RENAME EQU 0x0F //Rename a file on the host system. SYS_REMOVE EQU 0x0E //Remove a file on the host system.
SYS_TMPNAM EQU 0x0D //Get a temporary absolute file path to create a temporary file. SYS_SEEK EQU 0x0A //Set the file cursor to a given position in a file. SYS_FLEN EQU 0x0C //Get the length of a file. SYS_CLOSE EQU 0x02 //Closes a file on the host which has been opened by SYS_OPEN. SYS_READ EQU 0x06 //Read from a file at the current cursor position. SYS_WRITE EQU 0x05 //Write to a file or stream. SYS_ISTTY EQU 0x09 //Check whether a file handle is associated with a file or a stream/terminal such as stdout. * File operations */ SYS_OPEN EQU 0x01 //Open a file or stream on the host system. The following is a list of the semihosting operations defined by ARM 2: Return the result in r0 before allowing the processor to continue running its While the CPU is still halted, the host will execute the requested operation and Reading the content of r0, and, if necessary, accesses all other function The debugger agent then figures out the operation requested by the target by This indicates to the host that the target is requesting a semihosting Sending a supervisor call instruction ( SVC 0xAB or SVC 0x123456) depending Into a breakpoint instruction ( BKPT 0xAB for ARMv6-M or ARMv7-M) or by This is done by halting the CPU target by the debugger agent, either by running Screen, the keyboard, or the disk of the host. Printf(), scanf, or even fopen, and have these interact directly with the In other words, an ARM based MCU can run C library functions, such as On a host computer that is running a debugger. According to ARM documentation 1, semihosting is a mechanism that enablesĬode running on an ARM target to communicate and use the Input/Output facilities
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