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-rw-r--r--libgloss/arm/crt0.S359
1 files changed, 359 insertions, 0 deletions
diff --git a/libgloss/arm/crt0.S b/libgloss/arm/crt0.S
new file mode 100644
index 0000000..7f36b12
--- /dev/null
+++ b/libgloss/arm/crt0.S
@@ -0,0 +1,359 @@
+#include "swi.h"
+
+/* ANSI concatenation macros. */
+#define CONCAT(a, b) CONCAT2(a, b)
+#define CONCAT2(a, b) a ## b
+
+#ifdef __USER_LABEL_PREFIX__
+#define FUNCTION( name ) CONCAT (__USER_LABEL_PREFIX__, name)
+#else
+#error __USER_LABEL_PREFIX is not defined
+#endif
+
+/* .text is used instead of .section .text so it works with arm-aout too. */
+ .text
+ .code 32
+ .align 0
+
+ .global _mainCRTStartup
+ .global _start
+ .global start
+start:
+_start:
+_mainCRTStartup:
+
+/* Start by setting up a stack */
+#ifdef ARM_RDP_MONITOR
+ /* Issue Demon SWI to read stack info */
+ swi SWI_GetEnv /* Returns command line in r0 */
+ mov sp,r1 /* and the highest memory address in r1 */
+ ldr sl, .LC2 /* stack limit is at end of data */
+ add sl, sl, #256 /* allow slop for stack overflow handling */
+ /* and small frames */
+#else
+#ifdef ARM_RDI_MONITOR
+ /* Issue Angel SWI to read stack info */
+ mov r0, #AngelSWI_Reason_HeapInfo
+ adr r1, .LC0 /* point at ptr to 4 words to receive data */
+ swi AngelSWI_ARM /* We are always in ARM mode for startup */
+ ldr r0, .LC0 /* point at values read */
+ ldr sp, [r0, #8]
+ ldr sl, [r0, #12]
+ add sl, sl, #256 /* allow slop for stack overflow handling */
+ /* and small frames */
+#else
+ /* Set up the stack pointer to a fixed value */
+ /* Changes by toralf:
+ - Allow linker script to provide stack via __stack symbol - see
+ defintion of .Lstack
+ - Provide "hooks" that may be used by the application to add
+ custom init code - see .Lhwinit and .Lswinit
+ - Go through all execution modes and set up stack for each of them.
+ Loosely based on init.s from ARM/Motorola example code.
+ Note: Mode switch via CPSR is not allowed once in non-privileged
+ mode, so we take care not to enter "User" to set up its sp,
+ and also skip most operations if already in that mode. */
+
+ ldr r3, .Lstack
+ cmp r3, #0
+ ldreq r3, .LC0
+ /* Note: This 'mov' is essential when starting in User, and ensures we
+ always get *some* sp value for the initial mode, even if we
+ have somehow missed it below (in which case it gets the same
+ value as FIQ - not ideal, but better than nothing.) */
+ mov sp, r3
+ mrs r2, CPSR
+ tst r2, #0x0F /* Test mode bits - in User of all are 0 */
+ beq .LC23 /* "eq" means r2 AND #0x0F is 0 */
+ msr CPSR_c, #0xD1 /* FIRQ mode, interrupts disabled */
+ mov sp, r3
+ sub sl, sp, #0x1000 /* This mode also has its own sl (see below) */
+
+ mov r3, sl
+ msr CPSR_c, #0xD7 /* Abort mode, interrupts disabled */
+ mov sp, r3
+ sub r3, r3, #0x1000
+
+ msr CPSR_c, #0xDB /* Undefined mode, interrupts disabled */
+ mov sp, r3
+ sub r3, r3, #0x1000
+
+ msr CPSR_c, #0xD2 /* IRQ mode, interrupts disabled */
+ mov sp, r3
+ sub r3, r3, #0x2000
+
+ msr CPSR_c, #0xD3 /* Supervisory mode, interrupts disabled */
+ mov sp, r3
+ sub r3, r3, #0x8000 /* Min size 32k */
+ bic r3, r3, #0x00FF /* Align with current 64k block */
+ bic r3, r3, #0xFF00
+
+ str r3, [r3, #-4] /* Move value into user mode sp without */
+ ldmdb r3, {sp}^ /* changing modes, via '^' form of ldm */
+
+ orr r2, r2, #0xC0 /* Back to original mode, presumably SVC, */
+ msr CPSR_c, r2 /* with FIQ/IRQ disable bits forced to 1 */
+.LC23:
+ /* Setup a default stack-limit in-case the code has been
+ compiled with "-mapcs-stack-check". Hard-wiring this value
+ is not ideal, since there is currently no support for
+ checking that the heap and stack have not collided, or that
+ this default 64k is enough for the program being executed.
+ However, it ensures that this simple crt0 world will not
+ immediately cause an overflow event: */
+ sub sl, r3, #64 << 10 /* Still assumes 256bytes below sl */
+#endif
+#endif
+ /* Zero the memory in the .bss section. */
+ mov a2, #0 /* Second arg: fill value */
+ mov fp, a2 /* Null frame pointer */
+ mov r7, a2 /* Null frame pointer for Thumb */
+
+ ldr a1, .LC1 /* First arg: start of memory block */
+ ldr a3, .LC2
+ sub a3, a3, a1 /* Third arg: length of block */
+
+
+#ifdef __thumb__ /* Enter Thumb mode.... */
+
+ add a4, pc, #1 /* Get the address of the Thumb block */
+ bx a4 /* Go there and start Thumb decoding */
+
+ .code 16
+ .global __change_mode
+ .thumb_func
+__change_mode:
+#endif
+
+ bl FUNCTION (memset)
+#if !defined (ARM_RDP_MONITOR) && !defined (ARM_RDI_MONITOR)
+/* Changes by toralf: Taken from libgloss/m68k/crt0.S
+ * initialize target specific stuff. Only execute these
+ * functions it they exist.
+ */
+ ldr r3, .Lhwinit
+ cmp r3, #0
+ beq .LC24
+ mov lr, pc
+ mov pc, r3
+.LC24:
+ ldr r3, .Lswinit
+ cmp r3, #0
+ beq .LC25
+ mov lr, pc
+ mov pc, r3
+.LC25:
+ mov r0, #0 /* no arguments */
+ mov r1, #0 /* no argv either */
+#else
+ /* Need to set up standard file handles */
+ bl FUNCTION (initialise_monitor_handles)
+
+#ifdef ARM_RDP_MONITOR
+ swi SWI_GetEnv /* sets r0 to point to the command line */
+ mov r1, r0
+#else
+ mov r0, #AngelSWI_Reason_GetCmdLine
+ adr r1, .LC30 /* Space for command line */
+ swi AngelSWI
+ ldr r1, .LC30
+#endif
+ /* Parse string at r1 */
+ mov r0, #0 /* count of arguments so far */
+ /* Push a NULL argument onto the end of the list. */
+#ifdef __thumb__
+ push {r0}
+#else
+ stmfd sp!, {r0}
+#endif
+.LC10:
+/* Skip leading blanks */
+#ifdef __thumb__
+ ldrb r3, [r1]
+ add r1, #1
+#else
+ ldrb r3, [r1], #1
+#endif
+ cmp r3, #0
+ beq .LC12
+ cmp r3, #' '
+ beq .LC10
+
+/* See whether we are scanning a string */
+ cmp r3, #'"'
+#ifdef __thumb__
+ beq .LC20
+ cmp r3, #'\''
+ bne .LC21
+.LC20:
+ mov r2, r3
+ b .LC22
+
+.LC21:
+ mov r2, #' ' /* terminator type */
+ sub r1, r1, #1 /* adjust back to point at start char */
+.LC22:
+#else
+ cmpne r3, #'\''
+ moveq r2, r3
+ movne r2, #' ' /* terminator type */
+ subne r1, r1, #1 /* adjust back to point at start char */
+#endif
+
+/* Stack a pointer to the current argument */
+#ifdef __thumb__
+ push {r1}
+#else
+ stmfd sp!, {r1}
+#endif
+ add r0, r0, #1
+.LC11:
+#ifdef __thumb__
+ ldrb r3, [r1]
+ add r1, #1
+#else
+ ldrb r3, [r1], #1
+#endif
+ cmp r3, #0
+ beq .LC12
+ cmp r2, r3 /* reached terminator? */
+ bne .LC11
+ mov r2, #0
+ sub r3, r1, #1
+ strb r2, [r3] /* terminate the arg string */
+ b .LC10
+
+.LC12:
+ mov r1, sp /* point at stacked arg pointers */
+ /* We've now got the stacked args in order reverse the */
+#ifdef __thumb__
+ mov r2, r0
+ lsl r2, #2
+ add r2, sp
+ mov r3, sp
+.LC15: cmp r2, r3
+ bls .LC14
+ sub r2, #4
+ ldr r4, [r2]
+ ldr r5, [r3]
+ str r5, [r2]
+ str r4, [r3]
+ add r3, #4
+ b .LC15
+.LC14:
+#else
+ add r2, sp, r0, LSL #2 /* End of args */
+ mov r3, sp /* Start of args */
+.LC13: cmp r2, r3
+ ldrhi r4,[r2, #-4] /* Reverse ends of list */
+ ldrhi r5, [r3]
+ strhi r5, [r2, #-4]!
+ strhi r4, [r3], #4
+ bhi .LC13
+#endif
+#endif
+
+#ifdef __USES_INITFINI__
+ /* Some arm/elf targets use the .init and .fini sections
+ to create constructors and destructors, and for these
+ targets we need to call the _init function and arrange
+ for _fini to be called at program exit. */
+ mov r4, r0
+ mov r5, r1
+ ldr r0, .Lfini
+ bl FUNCTION (atexit)
+ bl FUNCTION (_init)
+ mov r0, r4
+ mov r1, r5
+#endif
+ bl FUNCTION (main)
+
+ bl FUNCTION (exit) /* Should not return. */
+
+#ifdef __thumb__
+ /* Come out of Thumb mode. This code should be redundant. */
+
+ mov a4, pc
+ bx a4
+
+ .code 32
+ .global change_back
+change_back:
+ /* Halt the execution. This code should never be executed. */
+ /* With no debug monitor, this probably aborts (eventually).
+ With a Demon debug monitor, this halts cleanly.
+ With an Angel debug monitor, this will report 'Unknown SWI'. */
+ swi SWI_Exit
+#endif
+
+ /* For Thumb, constants must be after the code since only
+ positive offsets are supported for PC relative addresses. */
+
+ .align 0
+.LC0:
+#ifdef ARM_RDI_MONITOR
+ .word HeapBase
+#else
+#ifndef ARM_RDP_MONITOR
+ /* Changes by toralf: Provide alternative "stack" variable whose value
+ may be defined externally; .Lstack will be used instead of .LC0 if
+ it points to a non-0 value. Also set up references to "hooks" that
+ may be used by the application to provide additional init code. */
+
+#ifdef __pe__
+ .word 0x800000
+#else
+ .word 0x80000 /* Top of RAM on the PIE board. */
+#endif
+.Lstack:
+ .word __stack
+.Lhwinit:
+ .word FUNCTION (hardware_init_hook)
+.Lswinit:
+ .word FUNCTION (software_init_hook)
+
+ /* Set up defaults for the above variables in the form of weak symbols
+ - so that application will link correctly, and get value 0 in
+ runtime (meaning "ignore setting") for the variables, when the user
+ does not provide the symbols. (The linker uses a weak symbol if,
+ and only if, a normal version of the same symbol isn't provided
+ e.g. by a linker script or another object file.) */
+
+ .set __stack, 0
+ .set FUNCTION (hardware_init_hook), 0
+ .set FUNCTION (software_init_hook), 0
+
+ .weak __stack
+ .weak FUNCTION (hardware_init_hook)
+ .weak FUNCTION (software_init_hook)
+#endif
+
+#endif
+.LC1:
+ .word __bss_start__
+.LC2:
+ .word __bss_end__
+#ifdef __USES_INITFINI__
+.Lfini:
+ .word FUNCTION(_fini)
+#endif
+#ifdef ARM_RDI_MONITOR
+.LC30:
+ .word CommandLine
+ .word 255
+
+/* Workspace for Angel calls. */
+ .data
+/* Data returned by monitor SWI. */
+.global __stack_base__
+HeapBase: .word 0
+HeapLimit: .word 0
+__stack_base__: .word 0
+StackLimit: .word 0
+CommandLine: .space 256,0 /* Maximum length of 255 chars handled. */
+#endif
+
+#ifdef __pe__
+ .section .idata$3
+ .long 0,0,0,0,0,0,0,0
+#endif