Re: [PATCH 2/2] [Arm] Stack Pointer and Stack Limit initialization refactored.
Alexander Fedotov <[email protected]>
| Newsgroups | gmane.comp.lib.newlib |
|---|---|
| Message-ID | <CAN8C2Cq-zbKTZ5EXz-6JwnPE6goXqV1-k6a09LKWPJJ4zwF1DQ@mail.gmail.com> |
Ping^4 On Mon, 13 May 2019 at 16:25, Alexander Fedotov <[email protected]> wrote: > Ping^3 > > On Thu, Apr 25, 2019 at 1:21 PM Alexander Fedotov <[email protected]> > wrote: > > > > Ping^2 > > > > On Wed, Apr 17, 2019 at 12:17 PM Alexander Fedotov <[email protected]> > wrote: > > > > > > Ping > > > > > > On Fri, 12 Apr 2019 at 16:31, <[email protected]> wrote: > > >> > > >> From: Alexander Fedotov <[email protected]> > > >> > > >> SP initialization changes: > > >> 1. set default value in semihosting case as well > > >> 2. moved existing SP & SL init code for processor modes in separate > routine and made it as "hook" > > >> 3. init SP for processor modes in Thumb mode as well > > >> > > >> Add new macro FN_RETURN, FN_EH_START and FN_EH_END. > > >> --- > > >> libgloss/arm/arm.h | 26 ++++ > > >> libgloss/arm/crt0.S | 277 > ++++++++++++++++++++++++++----------- > > >> newlib/libc/sys/arm/arm.h | 26 ++++ > > >> newlib/libc/sys/arm/crt0.S | 277 > ++++++++++++++++++++++++++----------- > > >> 4 files changed, 440 insertions(+), 166 deletions(-) > > >> > > >> diff --git a/libgloss/arm/arm.h b/libgloss/arm/arm.h > > >> index 0489f2d92..04b3a5ac7 100644 > > >> --- a/libgloss/arm/arm.h > > >> +++ b/libgloss/arm/arm.h > > >> @@ -61,4 +61,30 @@ > > >> # define HAVE_CALL_INDIRECT > > >> #endif > > >> > > >> +/* A and R profiles (and legacy Arm). > > >> + Current Program Status Register (CPSR) > > >> + M[4:0] Mode bits. M[4] is always 1 for 32-bit modes. > > >> + T[5] 1: Thumb, 0: ARM instruction set > > >> + F[6] 1: disables FIQ > > >> + I[7] 1: disables IRQ > > >> + A[8] 1: disables imprecise aborts > > >> + E[9] 0: Little-endian, 1: Big-endian > > >> + J[24] 1: Jazelle instruction set > > >> + */ > > >> +#define CPSR_M_USR 0x00 /* User mode */ > > >> +#define CPSR_M_FIQ 0x01 /* Fast Interrupt > mode */ > > >> +#define CPSR_M_IRQ 0x02 /* Interrupt mode */ > > >> +#define CPSR_M_SVR 0x03 /* Supervisor mode */ > > >> +#define CPSR_M_MON 0x06 /* Monitor mode */ > > >> +#define CPSR_M_ABT 0x07 /* Abort mode */ > > >> +#define CPSR_M_HYP 0x0A /* Hypervisor mode */ > > >> +#define CPSR_M_UND 0x0B /* Undefined mode */ > > >> +#define CPSR_M_SYS 0x0F /* System mode */ > > >> +#define CPSR_M_32BIT 0x10 /* 32-bit mode */ > > >> +#define CPSR_T_BIT 0x20 /* Thumb bit */ > > >> +#define CPSR_F_MASK 0x40 /* FIQ bit */ > > >> +#define CPSR_I_MASK 0x80 /* IRQ bit */ > > >> + > > >> +#define CPSR_M_MASK 0x0F /* Mode mask except > M[4] */ > > >> + > > >> #endif /* _LIBGLOSS_ARM_H */ > > >> diff --git a/libgloss/arm/crt0.S b/libgloss/arm/crt0.S > > >> index 1deb73aa5..95aa3b578 100644 > > >> --- a/libgloss/arm/crt0.S > > >> +++ b/libgloss/arm/crt0.S > > >> @@ -59,6 +59,21 @@ > > >> .endm > > >> #endif > > >> > > >> +/* Annotation for EABI unwinding tables. */ > > >> +.macro FN_EH_START > > >> +#if defined(__ELF__) && !defined(__USING_SJLJ_EXCEPTIONS__) > > >> + .fnstart > > >> +#endif > > >> +.endm > > >> + > > >> +.macro FN_EH_END > > >> +#if defined(__ELF__) && !defined(__USING_SJLJ_EXCEPTIONS__) > > >> + /* Protect against unhandled exceptions. */ > > >> + .cantunwind > > >> + .fnend > > >> +#endif > > >> +.endm > > >> + > > >> .macro indirect_call reg > > >> #ifdef HAVE_CALL_INDIRECT > > >> blx \reg > > >> @@ -68,16 +83,170 @@ > > >> #endif > > >> .endm > > >> > > >> +/* For armv4t and newer, toolchains will transparently convert > > >> + 'bx lr' to 'mov pc, lr' if needed. GCC has deprecated support > > >> + for anything older than armv4t, but this should handle that > > >> + corner case in case anyone needs it anyway */ > > >> +.macro FN_RETURN > > >> +#if __ARM_ARCH <= 4 && __ARM_ARCH_ISA_THUMB == 0 > > >> + mov pc, lr > > >> +#else > > >> + bx lr > > >> +#endif > > >> +.endm > > >> + > > >> + > > >> + > > >> > +/****************************************************************************** > > >> +* User mode only: This routine makes default target > specific Stack > > >> +* +-----+ <- SL_sys, Pointer initialization for different > processor modes: > > >> +* | | SL_usr FIQ, Abort, IRQ, Undefined, Supervisor, > System (User) > > >> +* | SYS | and setups a default Stack Limit in-case > the code has > > >> +* | USR | -=0x10000 been compiled with "-mapcs-stack-check" > for FIQ and > > >> +* | | System (User) modes. > > >> +* | | > > >> +* +-----+ <- initial SP, > > >> +* becomes SP_sys Hard-wiring SL value is not ideal, > since there is > > >> +* and SL_usr currently no support for checking that > the heap and > > >> +* stack have not collided, or that this > default 64k is > > >> +* All modes: is enough for the program being executed. > However, > > >> +* +-----+ <- SL_sys, it ensures that this simple crt0 world > will not > > >> +* | | SL_usr immediately cause an overflow event. > > >> +* | SYS | > > >> +* | USR | -=0x10000 We go through all execution modes and > set up SP > > >> +* | | for each of them. > > >> +* +-----+ <- SP_sys, > > >> +* | | SP_usr Note: > > >> +* | SVC | -= 0x8000 Mode switch via CPSR is not allowed > once in > > >> +* | | non-privileged mode, so we take care > not to enter > > >> +* +-----+ <- SP_svc "User" to set up its sp, and also skip > most > > >> +* | | operations if already in that mode. > > >> +* | IRQ | -= 0x2000 > > >> +* | | Input parameters: > > >> +* ^ +-----+ <- SP_und - sp - Initialized SP > > >> +* s | | - r2 - May contain SL value from > semihosting > > >> +* t | UND | -= 0x1000 SYS_HEAPINFO call > > >> +* a | | Scratch registers: > > >> +* c +-----+ <- SP_und - r1 - new value of CPSR > > >> +* k | | - r2 - intermediate value (in standalone > mode) > > >> +* | ABT | -= 0x1000 - r3 - new SP value > > >> +* g | | - r4 - save/restore CPSR on entry/exit > > >> +* r +-----+ <- SP_abt, > > >> +* o | | SL_fiq Declared as "weak" so that user can > write and use > > >> +* w | FIQ | -= 0x1000 his own implementation if current doesn't > fit. > > >> +* t | | > > >> +* h +-----+ <- initial SP, > > >> +* becomes SP_fiq > > >> +* > > >> > +******************************************************************************/ > > >> + .align 0 > > >> + FUNC_START _stack_init > > >> + .weak FUNCTION (_stack_init) > > >> + FN_EH_START > > >> + > > >> + /* M profile doesn't have CPSR register. */ > > >> +#if (__ARM_ARCH_PROFILE != 'M') > > >> + /* Following code is compatible for both ARM and Thumb ISA */ > > >> + mrs r4, CPSR > > >> + /* Test mode bits - in User of all are 0 */ > > >> + tst r4, #(CPSR_M_MASK) > > >> + /* "eq" means r4 AND #0x0F is 0 */ > > >> + beq .Lskip_cpu_modes > > >> + > > >> + mov r3, sp /* save input SP value */ > > >> + > > >> + /* FIQ mode, interrupts disabled */ > > >> + mov r1, #(CPSR_M_FIQ|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> + sub sl, sp, #0x1000 /* FIQ mode has its own SL */ > > >> + > > >> + /* Abort mode, interrupts disabled */ > > >> + mov r3, sl > > >> + mov r1, #(CPSR_M_ABT|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> + sub r3, r3, #0x1000 > > >> + > > >> + /* Undefined mode, interrupts disabled */ > > >> + mov r1, #(CPSR_M_UND|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> + sub r3, r3, #0x1000 > > >> + > > >> + /* IRQ mode, interrupts disabled */ > > >> + mov r1, #(CPSR_M_IRQ|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> + sub r3, r3, #0x2000 > > >> + > > >> + /* Supervisory mode, interrupts disabled */ > > >> + mov r1, #(CPSR_M_SVR|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> + > > >> + sub r3, r3, #0x8000 /* Min size 32k */ > > >> + bic r3, r3, #0x00FF /* Align with current 64k block */ > > >> + bic r3, r3, #0xFF00 > > >> + > > >> +# if __ARM_ARCH >= 4 > > >> + /* System (shares regs with User) mode, interrupts disabled */ > > >> + mov r1, #(CPSR_M_SYS|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> +# else > > >> + /* Keep this for ARMv3, but GCC actually dropped it. */ > > >> + /* Move value into user mode sp without changing modes, */ > > >> + /* via '^' form of ldm */ > > >> + str r3, [r3, #-4] > > >> + ldmdb r3, {sp}^ > > >> +# endif > > >> + > > >> + /* Back to original mode, presumably SVC, with diabled > FIQ/IRQ */ > > >> + orr r4, r4, #(CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r4 > > >> + > > >> +.Lskip_cpu_modes: > > >> +#endif > > >> + > > >> + /* Set SL register */ > > >> +#if defined (ARM_RDI_MONITOR) /* semihosting */ > > >> + cmp r2, #0 > > >> + beq .Lsl_forced_zero > > >> + /* allow slop for stack overflow handling and small frames */ > > >> +# ifdef THUMB1_ONLY > > >> + adds r2, #128 > > >> + adds r2, #128 > > >> + mov sl, r2 > > >> +# else > > >> + add sl, r2, #256 > > >> +# endif > > >> +.Lsl_forced_zero: > > >> + > > >> +#else /* standalone */ > > >> + /* r3 contains SP for System/User mode. Set SL = SP - 0x10000 > */ > > >> + #ifdef THUMB1_ONLY > > >> + movs r2, #64 > > >> + lsls r2, r2, #10 > > >> + subs r2, r3, r2 > > >> + mov sl, r2 > > >> + #else > > >> + /* Still assumes 256bytes below sl */ > > >> + sub sl, r3, #64 << 10 > > >> + #endif > > >> +#endif > > >> + > > >> + FN_RETURN > > >> + FN_EH_END > > >> + > > >> + > > >> > /******************************************************************************* > > >> * Main library startup code. > > >> > *******************************************************************************/ > > >> .align 0 > > >> FUNC_START _mainCRTStartup > > >> FUNC_START _start > > >> -#if defined(__ELF__) && !defined(__USING_SJLJ_EXCEPTIONS__) > > >> - /* Annotation for EABI unwinding tables. */ > > >> - .fnstart > > >> -#endif > > >> + FN_EH_START > > >> > > >> /* __ARM_ARCH_PROFILE is defined from GCC 4.8 onwards, > however __ARM_ARCH_7A > > >> has been defined since 4.2 onwards, which is when v7-a > support was added > > >> @@ -150,36 +319,27 @@ > > >> to skip setting sp/sl to 0 here. > > >> - Considering M-profile processors, We might want to > initialize > > >> sp by the first entry of vector table and return 0 to > SYS_HEAPINFO > > >> - semihosting call, which will be skipped here. */ > > >> + semihosting call, which will be skipped here. > > >> + - Considering R-profile processors there is no automatic > SP init by hardware > > >> + so we need to initialize it by default value. */ > > >> + ldr r3, .Lstack > > >> cmp r1, #0 > > >> beq .LC26 > > >> - mov sp, r1 > > >> + mov r3, r1 > > >> .LC26: > > >> - cmp r2, #0 > > >> - beq .LC27 > > >> + mov sp, r3 > > >> > > >> - /* Allow slop for stack overflow handling and small frames. > */ > > >> -#ifdef THUMB1_ONLY > > >> - adds r2, #128 > > >> - adds r2, #128 > > >> - mov sl, r2 > > >> -#else > > >> - add sl, r2, #256 > > >> -#endif > > >> + /* r2 (SL value) will be used in _stack_init */ > > >> + bl FUNCTION (_stack_init) > > >> > > >> -.LC27: > > >> -#else > > >> - /* Set up the stack pointer to a fixed value. */ > > >> + > > >> +#else /* standalone */ > > >> + /* 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. */ > > >> + custom init code - see .Lhwinit and .Lswinit */ > > >> > > >> ldr r3, .Lstack > > >> cmp r3, #0 > > >> @@ -198,57 +358,10 @@ > > >> have somehow missed it below (in which case it gets > the same > > >> value as FIQ - not ideal, but better than nothing). > */ > > >> mov sp, r3 > > >> -#ifdef PREFER_THUMB > > >> - /* XXX Fill in stack assignments for interrupt modes. */ > > >> -#else > > >> - 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. */ > > >> + /* we don't care of r2 value in standalone */ > > >> + bl FUNCTION (_stack_init) > > >> > > >> - 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. */ > > >> -#endif > > >> -.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: */ > > >> -#ifdef THUMB1_ONLY > > >> - movs r2, #64 > > >> - lsls r2, r2, #10 > > >> - subs r2, r3, r2 > > >> - mov sl, r2 > > >> -#else > > >> - sub sl, r3, #64 << 10 /* Still assumes 256bytes > below sl. */ > > >> -#endif > > >> #endif > > >> #endif > > >> /* Zero the memory in the .bss section. */ > > >> @@ -447,6 +560,8 @@ change_back: > > >> swi SWI_Exit > > >> #endif > > >> > > >> + FN_EH_END > > >> + > > >> /* For Thumb, constants must be after the code since only > > >> positive offsets are supported for PC relative addresses. > */ > > >> .align 0 > > >> @@ -464,9 +579,6 @@ change_back: > > >> #else > > >> .word 0x80000 /* Top of RAM on the PIE > board. */ > > >> #endif > > >> - > > >> -.Lstack: > > >> - .word __stack > > >> .Lhwinit: > > >> .word FUNCTION (hardware_init_hook) > > >> .Lswinit: > > >> @@ -479,17 +591,16 @@ change_back: > > >> and only if, a normal version of the same symbol isn't > provided > > >> e.g. by a linker script or another object file.) */ > > >> > > >> - .weak __stack > > >> .weak FUNCTION (hardware_init_hook) > > >> .weak FUNCTION (software_init_hook) > > >> #endif > > >> > > >> #endif > > >> -#if defined(__ELF__) && !defined(__USING_SJLJ_EXCEPTIONS__) > > >> - /* Protect against unhandled exceptions. */ > > >> - .cantunwind > > >> - .fnend > > >> -#endif > > >> + > > >> +.Lstack: > > >> + .word __stack > > >> + .weak __stack > > >> + > > >> .LC1: > > >> .word __bss_start__ > > >> .LC2: > > >> diff --git a/newlib/libc/sys/arm/arm.h b/newlib/libc/sys/arm/arm.h > > >> index 0489f2d92..04b3a5ac7 100644 > > >> --- a/newlib/libc/sys/arm/arm.h > > >> +++ b/newlib/libc/sys/arm/arm.h > > >> @@ -61,4 +61,30 @@ > > >> # define HAVE_CALL_INDIRECT > > >> #endif > > >> > > >> +/* A and R profiles (and legacy Arm). > > >> + Current Program Status Register (CPSR) > > >> + M[4:0] Mode bits. M[4] is always 1 for 32-bit modes. > > >> + T[5] 1: Thumb, 0: ARM instruction set > > >> + F[6] 1: disables FIQ > > >> + I[7] 1: disables IRQ > > >> + A[8] 1: disables imprecise aborts > > >> + E[9] 0: Little-endian, 1: Big-endian > > >> + J[24] 1: Jazelle instruction set > > >> + */ > > >> +#define CPSR_M_USR 0x00 /* User mode */ > > >> +#define CPSR_M_FIQ 0x01 /* Fast Interrupt > mode */ > > >> +#define CPSR_M_IRQ 0x02 /* Interrupt mode */ > > >> +#define CPSR_M_SVR 0x03 /* Supervisor mode */ > > >> +#define CPSR_M_MON 0x06 /* Monitor mode */ > > >> +#define CPSR_M_ABT 0x07 /* Abort mode */ > > >> +#define CPSR_M_HYP 0x0A /* Hypervisor mode */ > > >> +#define CPSR_M_UND 0x0B /* Undefined mode */ > > >> +#define CPSR_M_SYS 0x0F /* System mode */ > > >> +#define CPSR_M_32BIT 0x10 /* 32-bit mode */ > > >> +#define CPSR_T_BIT 0x20 /* Thumb bit */ > > >> +#define CPSR_F_MASK 0x40 /* FIQ bit */ > > >> +#define CPSR_I_MASK 0x80 /* IRQ bit */ > > >> + > > >> +#define CPSR_M_MASK 0x0F /* Mode mask except > M[4] */ > > >> + > > >> #endif /* _LIBGLOSS_ARM_H */ > > >> diff --git a/newlib/libc/sys/arm/crt0.S b/newlib/libc/sys/arm/crt0.S > > >> index 7a6b40d9a..0929a435e 100644 > > >> --- a/newlib/libc/sys/arm/crt0.S > > >> +++ b/newlib/libc/sys/arm/crt0.S > > >> @@ -59,6 +59,21 @@ > > >> .endm > > >> #endif > > >> > > >> +/* Annotation for EABI unwinding tables. */ > > >> +.macro FN_EH_START > > >> +#if defined(__ELF__) && !defined(__USING_SJLJ_EXCEPTIONS__) > > >> + .fnstart > > >> +#endif > > >> +.endm > > >> + > > >> +.macro FN_EH_END > > >> +#if defined(__ELF__) && !defined(__USING_SJLJ_EXCEPTIONS__) > > >> + /* Protect against unhandled exceptions. */ > > >> + .cantunwind > > >> + .fnend > > >> +#endif > > >> +.endm > > >> + > > >> .macro indirect_call reg > > >> #ifdef HAVE_CALL_INDIRECT > > >> blx \reg > > >> @@ -68,16 +83,170 @@ > > >> #endif > > >> .endm > > >> > > >> +/* For armv4t and newer, toolchains will transparently convert > > >> + 'bx lr' to 'mov pc, lr' if needed. GCC has deprecated support > > >> + for anything older than armv4t, but this should handle that > > >> + corner case in case anyone needs it anyway */ > > >> +.macro FN_RETURN > > >> +#if __ARM_ARCH <= 4 && __ARM_ARCH_ISA_THUMB == 0 > > >> + mov pc, lr > > >> +#else > > >> + bx lr > > >> +#endif > > >> +.endm > > >> + > > >> + > > >> + > > >> > +/****************************************************************************** > > >> +* User mode only: This routine makes default target > specific Stack > > >> +* +-----+ <- SL_sys, Pointer initialization for different > processor modes: > > >> +* | | SL_usr FIQ, Abort, IRQ, Undefined, Supervisor, > System (User) > > >> +* | SYS | and setups a default Stack Limit in-case > the code has > > >> +* | USR | -=0x10000 been compiled with "-mapcs-stack-check" > for FIQ and > > >> +* | | System (User) modes. > > >> +* | | > > >> +* +-----+ <- initial SP, > > >> +* becomes SP_sys Hard-wiring SL value is not ideal, > since there is > > >> +* and SL_usr currently no support for checking that > the heap and > > >> +* stack have not collided, or that this > default 64k is > > >> +* All modes: is enough for the program being executed. > However, > > >> +* +-----+ <- SL_sys, it ensures that this simple crt0 world > will not > > >> +* | | SL_usr immediately cause an overflow event. > > >> +* | SYS | > > >> +* | USR | -=0x10000 We go through all execution modes and > set up SP > > >> +* | | for each of them. > > >> +* +-----+ <- SP_sys, > > >> +* | | SP_usr Note: > > >> +* | SVC | -= 0x8000 Mode switch via CPSR is not allowed > once in > > >> +* | | non-privileged mode, so we take care > not to enter > > >> +* +-----+ <- SP_svc "User" to set up its sp, and also skip > most > > >> +* | | operations if already in that mode. > > >> +* | IRQ | -= 0x2000 > > >> +* | | Input parameters: > > >> +* ^ +-----+ <- SP_und - sp - Initialized SP > > >> +* s | | - r2 - May contain SL value from > semihosting > > >> +* t | UND | -= 0x1000 SYS_HEAPINFO call > > >> +* a | | Scratch registers: > > >> +* c +-----+ <- SP_und - r1 - new value of CPSR > > >> +* k | | - r2 - intermediate value (in standalone > mode) > > >> +* | ABT | -= 0x1000 - r3 - new SP value > > >> +* g | | - r4 - save/restore CPSR on entry/exit > > >> +* r +-----+ <- SP_abt, > > >> +* o | | SL_fiq Declared as "weak" so that user can > write and use > > >> +* w | FIQ | -= 0x1000 his own implementation if current doesn't > fit. > > >> +* t | | > > >> +* h +-----+ <- initial SP, > > >> +* becomes SP_fiq > > >> +* > > >> > +******************************************************************************/ > > >> + .align 0 > > >> + FUNC_START _stack_init > > >> + .weak FUNCTION (_stack_init) > > >> + FN_EH_START > > >> + > > >> + /* M profile doesn't have CPSR register. */ > > >> +#if (__ARM_ARCH_PROFILE != 'M') > > >> + /* Following code is compatible for both ARM and Thumb ISA */ > > >> + mrs r4, CPSR > > >> + /* Test mode bits - in User of all are 0 */ > > >> + tst r4, #(CPSR_M_MASK) > > >> + /* "eq" means r4 AND #0x0F is 0 */ > > >> + beq .Lskip_cpu_modes > > >> + > > >> + mov r3, sp /* save input SP value */ > > >> + > > >> + /* FIQ mode, interrupts disabled */ > > >> + mov r1, #(CPSR_M_FIQ|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> + sub sl, sp, #0x1000 /* FIQ mode has its own SL */ > > >> + > > >> + /* Abort mode, interrupts disabled */ > > >> + mov r3, sl > > >> + mov r1, #(CPSR_M_ABT|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> + sub r3, r3, #0x1000 > > >> + > > >> + /* Undefined mode, interrupts disabled */ > > >> + mov r1, #(CPSR_M_UND|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> + sub r3, r3, #0x1000 > > >> + > > >> + /* IRQ mode, interrupts disabled */ > > >> + mov r1, #(CPSR_M_IRQ|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> + sub r3, r3, #0x2000 > > >> + > > >> + /* Supervisory mode, interrupts disabled */ > > >> + mov r1, #(CPSR_M_SVR|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> + > > >> + sub r3, r3, #0x8000 /* Min size 32k */ > > >> + bic r3, r3, #0x00FF /* Align with current 64k block */ > > >> + bic r3, r3, #0xFF00 > > >> + > > >> +# if __ARM_ARCH >= 4 > > >> + /* System (shares regs with User) mode, interrupts disabled */ > > >> + mov r1, #(CPSR_M_SYS|CPSR_M_32BIT|CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r1 > > >> + mov sp, r3 > > >> +# else > > >> + /* Keep this for ARMv3, but GCC actually dropped it. */ > > >> + /* Move value into user mode sp without changing modes, */ > > >> + /* via '^' form of ldm */ > > >> + str r3, [r3, #-4] > > >> + ldmdb r3, {sp}^ > > >> +# endif > > >> + > > >> + /* Back to original mode, presumably SVC, with diabled > FIQ/IRQ */ > > >> + orr r4, r4, #(CPSR_I_MASK|CPSR_F_MASK) > > >> + msr CPSR_c, r4 > > >> + > > >> +.Lskip_cpu_modes: > > >> +#endif > > >> + > > >> + /* Set SL register */ > > >> +#if defined (ARM_RDI_MONITOR) /* semihosting */ > > >> + cmp r2, #0 > > >> + beq .Lsl_forced_zero > > >> + /* allow slop for stack overflow handling and small frames */ > > >> +# ifdef THUMB1_ONLY > > >> + adds r2, #128 > > >> + adds r2, #128 > > >> + mov sl, r2 > > >> +# else > > >> + add sl, r2, #256 > > >> +# endif > > >> +.Lsl_forced_zero: > > >> + > > >> +#else /* standalone */ > > >> + /* r3 contains SP for System/User mode. Set SL = SP - 0x10000 > */ > > >> + #ifdef THUMB1_ONLY > > >> + movs r2, #64 > > >> + lsls r2, r2, #10 > > >> + subs r2, r3, r2 > > >> + mov sl, r2 > > >> + #else > > >> + /* Still assumes 256bytes below sl */ > > >> + sub sl, r3, #64 << 10 > > >> + #endif > > >> +#endif > > >> + > > >> + FN_RETURN > > >> + FN_EH_END > > >> + > > >> + > > >> > /******************************************************************************* > > >> * Main library startup code. > > >> > *******************************************************************************/ > > >> .align 0 > > >> FUNC_START _mainCRTStartup > > >> FUNC_START _start > > >> -#if defined(__ELF__) && !defined(__USING_SJLJ_EXCEPTIONS__) > > >> - /* Annotation for EABI unwinding tables. */ > > >> - .fnstart > > >> -#endif > > >> + FN_EH_START > > >> > > >> /* Start by setting up a stack. */ > > >> #ifdef ARM_RDP_MONITOR > > >> @@ -130,36 +299,27 @@ > > >> to skip setting sp/sl to 0 here. > > >> - Considering M-profile processors, We might want to > initialize > > >> sp by the first entry of vector table and return 0 to > SYS_HEAPINFO > > >> - semihosting call, which will be skipped here. */ > > >> + semihosting call, which will be skipped here. > > >> + - Considering R-profile processors there is no automatic > SP init by hardware > > >> + so we need to initialize it by default value. */ > > >> + ldr r3, .Lstack > > >> cmp r1, #0 > > >> beq .LC26 > > >> - mov sp, r1 > > >> + mov r3, r1 > > >> .LC26: > > >> - cmp r2, #0 > > >> - beq .LC27 > > >> + mov sp, r3 > > >> > > >> - /* Allow slop for stack overflow handling and small frames. > */ > > >> -#ifdef THUMB1_ONLY > > >> - adds r2, #128 > > >> - adds r2, #128 > > >> - mov sl, r2 > > >> -#else > > >> - add sl, r2, #256 > > >> -#endif > > >> + /* r2 (SL value) will be used in _stack_init */ > > >> + bl FUNCTION (_stack_init) > > >> > > >> -.LC27: > > >> -#else > > >> - /* Set up the stack pointer to a fixed value. */ > > >> + > > >> +#else /* standalone */ > > >> + /* 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. */ > > >> + custom init code - see .Lhwinit and .Lswinit */ > > >> > > >> ldr r3, .Lstack > > >> cmp r3, #0 > > >> @@ -178,57 +338,10 @@ > > >> have somehow missed it below (in which case it gets > the same > > >> value as FIQ - not ideal, but better than nothing). > */ > > >> mov sp, r3 > > >> -#ifdef PREFER_THUMB > > >> - /* XXX Fill in stack assignments for interrupt modes. */ > > >> -#else > > >> - 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. */ > > >> + /* we don't care of r2 value in standalone */ > > >> + bl FUNCTION (_stack_init) > > >> > > >> - 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. */ > > >> -#endif > > >> -.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: */ > > >> -#ifdef THUMB1_ONLY > > >> - movs r2, #64 > > >> - lsls r2, r2, #10 > > >> - subs r2, r3, r2 > > >> - mov sl, r2 > > >> -#else > > >> - sub sl, r3, #64 << 10 /* Still assumes 256bytes > below sl. */ > > >> -#endif > > >> #endif > > >> #endif > > >> /* Zero the memory in the .bss section. */ > > >> @@ -421,6 +534,8 @@ change_back: > > >> swi SWI_Exit > > >> #endif > > >> > > >> + FN_EH_END > > >> + > > >> /* For Thumb, constants must be after the code since only > > >> positive offsets are supported for PC relative addresses. > */ > > >> .align 0 > > >> @@ -438,9 +553,6 @@ change_back: > > >> #else > > >> .word 0x80000 /* Top of RAM on the PIE > board. */ > > >> #endif > > >> - > > >> -.Lstack: > > >> - .word __stack > > >> .Lhwinit: > > >> .word FUNCTION (hardware_init_hook) > > >> .Lswinit: > > >> @@ -453,17 +565,16 @@ change_back: > > >> and only if, a normal version of the same symbol isn't > provided > > >> e.g. by a linker script or another object file.) */ > > >> > > >> - .weak __stack > > >> .weak FUNCTION (hardware_init_hook) > > >> .weak FUNCTION (software_init_hook) > > >> #endif > > >> > > >> #endif > > >> -#if defined(__ELF__) && !defined(__USING_SJLJ_EXCEPTIONS__) > > >> - /* Protect against unhandled exceptions. */ > > >> - .cantunwind > > >> - .fnend > > >> -#endif > > >> + > > >> +.Lstack: > > >> + .word __stack > > >> + .weak __stack > > >> + > > >> .LC1: > > >> .word __bss_start__ > > >> .LC2: > > >> -- > > >> 2.17.1 > > >> >