cregit-Linux how code gets into the kernel

Release 4.9 tools/testing/selftests/powerpc/basic_asm.h

#ifndef _SELFTESTS_POWERPC_BASIC_ASM_H

#define _SELFTESTS_POWERPC_BASIC_ASM_H

#include <ppc-asm.h>
#include <asm/unistd.h>


#define LOAD_REG_IMMEDIATE(reg,expr) \
	lis     reg,(expr)@highest;     \
        ori     reg,reg,(expr)@higher;  \
        rldicr  reg,reg,32,31;  \
        oris    reg,reg,(expr)@high;    \
        ori     reg,reg,(expr)@l;

/*
 * Note: These macros assume that variables being stored on the stack are
 * doublewords, while this is usually the case it may not always be the
 * case for each use case.
 */
#if defined(_CALL_ELF) && _CALL_ELF == 2

#define STACK_FRAME_MIN_SIZE 32

#define STACK_FRAME_TOC_POS  24

#define __STACK_FRAME_PARAM(_param)  (32 + ((_param)*8))

#define __STACK_FRAME_LOCAL(_num_params,_var_num)  ((STACK_FRAME_PARAM(_num_params)) + ((_var_num)*8))
#else

#define STACK_FRAME_MIN_SIZE 112

#define STACK_FRAME_TOC_POS  40

#define __STACK_FRAME_PARAM(i)  (48 + ((i)*8))

/*
 * Caveat: if a function passed more than 8 doublewords, the caller will have
 * made more space... which would render the 112 incorrect.
 */

#define __STACK_FRAME_LOCAL(_num_params,_var_num)  (112 + ((_var_num)*8))
#endif

/* Parameter x saved to the stack */

#define STACK_FRAME_PARAM(var)    __STACK_FRAME_PARAM(var)

/* Local variable x saved to the stack after x parameters */

#define STACK_FRAME_LOCAL(num_params,var)    __STACK_FRAME_LOCAL(num_params,var)

#define STACK_FRAME_LR_POS   16

#define STACK_FRAME_CR_POS   8

/*
 * It is very important to note here that _extra is the extra amount of
 * stack space needed. This space can be accessed using STACK_FRAME_PARAM()
 * or STACK_FRAME_LOCAL() macros.
 *
 * r1 and r2 are not defined in ppc-asm.h (instead they are defined as sp
 * and toc). Kernel programmers tend to prefer rX even for r1 and r2, hence
 * %1 and %r2. r0 is defined in ppc-asm.h and therefore %r0 gets
 * preprocessed incorrectly, hence r0.
 */

#define PUSH_BASIC_STACK(_extra) \
	mflr    r0; \
        std     r0,STACK_FRAME_LR_POS(%r1); \
        stdu    %r1,-(_extra + STACK_FRAME_MIN_SIZE)(%r1); \
        mfcr    r0; \
        stw     r0,STACK_FRAME_CR_POS(%r1); \
        std     %r2,STACK_FRAME_TOC_POS(%r1);


#define POP_BASIC_STACK(_extra) \
	ld      %r2,STACK_FRAME_TOC_POS(%r1); \
        lwz     r0,STACK_FRAME_CR_POS(%r1); \
        mtcr    r0; \
        addi    %r1,%r1,(_extra + STACK_FRAME_MIN_SIZE); \
        ld      r0,STACK_FRAME_LR_POS(%r1); \
        mtlr    r0;

#endif /* _SELFTESTS_POWERPC_BASIC_ASM_H */

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