forked from Minki/linux
153086644f
The gcc switch -mprofile-kernel defines a new ABI for calling _mcount() very early in the function with minimal overhead. Although mprofile-kernel has been available since GCC 3.4, there were bugs which were only fixed recently. Currently it is known to work in GCC 4.9, 5 and 6. Additionally there are two possible code sequences generated by the flag, the first uses mflr/std/bl and the second is optimised to omit the std. Currently only gcc 6 has the optimised sequence. This patch supports both sequences. Initial work started by Vojtech Pavlik, used with permission. Key changes: - rework _mcount() to work for both the old and new ABIs. - implement new versions of ftrace_caller() and ftrace_graph_caller() which deal with the new ABI. - updates to __ftrace_make_nop() to recognise the new mcount calling sequence. - updates to __ftrace_make_call() to recognise the nop'ed sequence. - implement ftrace_modify_call(). - updates to the module loader to surpress the toc save in the module stub when calling mcount with the new ABI. Reviewed-by: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Torsten Duwe <duwe@suse.de> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
124 lines
3.7 KiB
C
124 lines
3.7 KiB
C
#ifndef _ASM_POWERPC_CODE_PATCHING_H
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#define _ASM_POWERPC_CODE_PATCHING_H
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/*
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* Copyright 2008, Michael Ellerman, IBM Corporation.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <asm/types.h>
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#include <asm/ppc-opcode.h>
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/* Flags for create_branch:
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* "b" == create_branch(addr, target, 0);
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* "ba" == create_branch(addr, target, BRANCH_ABSOLUTE);
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* "bl" == create_branch(addr, target, BRANCH_SET_LINK);
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* "bla" == create_branch(addr, target, BRANCH_ABSOLUTE | BRANCH_SET_LINK);
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*/
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#define BRANCH_SET_LINK 0x1
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#define BRANCH_ABSOLUTE 0x2
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unsigned int create_branch(const unsigned int *addr,
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unsigned long target, int flags);
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unsigned int create_cond_branch(const unsigned int *addr,
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unsigned long target, int flags);
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int patch_branch(unsigned int *addr, unsigned long target, int flags);
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int patch_instruction(unsigned int *addr, unsigned int instr);
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int instr_is_relative_branch(unsigned int instr);
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int instr_is_branch_to_addr(const unsigned int *instr, unsigned long addr);
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unsigned long branch_target(const unsigned int *instr);
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unsigned int translate_branch(const unsigned int *dest,
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const unsigned int *src);
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#ifdef CONFIG_PPC_BOOK3E_64
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void __patch_exception(int exc, unsigned long addr);
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#define patch_exception(exc, name) do { \
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extern unsigned int name; \
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__patch_exception((exc), (unsigned long)&name); \
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} while (0)
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#endif
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#define OP_RT_RA_MASK 0xffff0000UL
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#define LIS_R2 0x3c020000UL
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#define ADDIS_R2_R12 0x3c4c0000UL
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#define ADDI_R2_R2 0x38420000UL
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static inline unsigned long ppc_function_entry(void *func)
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{
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#if defined(CONFIG_PPC64)
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#if defined(_CALL_ELF) && _CALL_ELF == 2
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u32 *insn = func;
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/*
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* A PPC64 ABIv2 function may have a local and a global entry
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* point. We need to use the local entry point when patching
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* functions, so identify and step over the global entry point
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* sequence.
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*
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* The global entry point sequence is always of the form:
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*
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* addis r2,r12,XXXX
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* addi r2,r2,XXXX
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*
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* A linker optimisation may convert the addis to lis:
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*
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* lis r2,XXXX
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* addi r2,r2,XXXX
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*/
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if ((((*insn & OP_RT_RA_MASK) == ADDIS_R2_R12) ||
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((*insn & OP_RT_RA_MASK) == LIS_R2)) &&
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((*(insn+1) & OP_RT_RA_MASK) == ADDI_R2_R2))
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return (unsigned long)(insn + 2);
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else
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return (unsigned long)func;
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#else
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/*
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* On PPC64 ABIv1 the function pointer actually points to the
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* function's descriptor. The first entry in the descriptor is the
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* address of the function text.
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*/
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return ((func_descr_t *)func)->entry;
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#endif
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#else
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return (unsigned long)func;
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#endif
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}
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static inline unsigned long ppc_global_function_entry(void *func)
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{
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#if defined(CONFIG_PPC64) && defined(_CALL_ELF) && _CALL_ELF == 2
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/* PPC64 ABIv2 the global entry point is at the address */
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return (unsigned long)func;
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#else
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/* All other cases there is no change vs ppc_function_entry() */
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return ppc_function_entry(func);
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#endif
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}
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#ifdef CONFIG_PPC64
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/*
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* Some instruction encodings commonly used in dynamic ftracing
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* and function live patching.
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*/
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/* This must match the definition of STK_GOT in <asm/ppc_asm.h> */
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#if defined(_CALL_ELF) && _CALL_ELF == 2
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#define R2_STACK_OFFSET 24
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#else
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#define R2_STACK_OFFSET 40
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#endif
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#define PPC_INST_LD_TOC (PPC_INST_LD | ___PPC_RT(__REG_R2) | \
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___PPC_RA(__REG_R1) | R2_STACK_OFFSET)
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/* usually preceded by a mflr r0 */
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#define PPC_INST_STD_LR (PPC_INST_STD | ___PPC_RS(__REG_R0) | \
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___PPC_RA(__REG_R1) | PPC_LR_STKOFF)
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#endif /* CONFIG_PPC64 */
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#endif /* _ASM_POWERPC_CODE_PATCHING_H */
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