mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-17 11:46:51 +07:00
3c88c692c2
Currently pt_regs on x86_32 has an oddity in that kernel regs (!user_mode(regs)) are short two entries (esp/ss). This means that any code trying to use them (typically: regs->sp) needs to jump through some unfortunate hoops. Change the entry code to fix this up and create a full pt_regs frame. This then simplifies various trampolines in ftrace and kprobes, the stack unwinder, ptrace, kdump and kgdb. Much thanks to Josh for help with the cleanups! Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Josh Poimboeuf <jpoimboe@redhat.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org>
195 lines
3.8 KiB
ArmAsm
195 lines
3.8 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* Copyright (C) 2017 Steven Rostedt, VMware Inc.
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*/
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#include <linux/linkage.h>
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#include <asm/page_types.h>
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#include <asm/segment.h>
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#include <asm/export.h>
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#include <asm/ftrace.h>
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#include <asm/nospec-branch.h>
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#include <asm/frame.h>
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#include <asm/asm-offsets.h>
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# define function_hook __fentry__
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EXPORT_SYMBOL(__fentry__)
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#ifdef CONFIG_FRAME_POINTER
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# define MCOUNT_FRAME 1 /* using frame = true */
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#else
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# define MCOUNT_FRAME 0 /* using frame = false */
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#endif
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ENTRY(function_hook)
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ret
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END(function_hook)
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ENTRY(ftrace_caller)
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#ifdef CONFIG_FRAME_POINTER
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/*
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* Frame pointers are of ip followed by bp.
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* Since fentry is an immediate jump, we are left with
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* parent-ip, function-ip. We need to add a frame with
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* parent-ip followed by ebp.
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*/
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pushl 4(%esp) /* parent ip */
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pushl %ebp
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movl %esp, %ebp
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pushl 2*4(%esp) /* function ip */
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/* For mcount, the function ip is directly above */
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pushl %ebp
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movl %esp, %ebp
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#endif
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pushl %eax
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pushl %ecx
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pushl %edx
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pushl $0 /* Pass NULL as regs pointer */
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#ifdef CONFIG_FRAME_POINTER
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/* Load parent ebp into edx */
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movl 4*4(%esp), %edx
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#else
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/* There's no frame pointer, load the appropriate stack addr instead */
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lea 4*4(%esp), %edx
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#endif
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movl (MCOUNT_FRAME+4)*4(%esp), %eax /* load the rip */
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/* Get the parent ip */
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movl 4(%edx), %edx /* edx has ebp */
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movl function_trace_op, %ecx
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subl $MCOUNT_INSN_SIZE, %eax
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.globl ftrace_call
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ftrace_call:
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call ftrace_stub
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addl $4, %esp /* skip NULL pointer */
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popl %edx
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popl %ecx
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popl %eax
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#ifdef CONFIG_FRAME_POINTER
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popl %ebp
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addl $4,%esp /* skip function ip */
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popl %ebp /* this is the orig bp */
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addl $4, %esp /* skip parent ip */
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#endif
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.Lftrace_ret:
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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.globl ftrace_graph_call
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ftrace_graph_call:
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jmp ftrace_stub
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#endif
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/* This is weak to keep gas from relaxing the jumps */
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WEAK(ftrace_stub)
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ret
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END(ftrace_caller)
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ENTRY(ftrace_regs_caller)
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/*
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* We're here from an mcount/fentry CALL, and the stack frame looks like:
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*
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* <previous context>
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* RET-IP
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*
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* The purpose of this function is to call out in an emulated INT3
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* environment with a stack frame like:
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*
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* <previous context>
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* gap / RET-IP
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* gap
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* gap
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* gap
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* pt_regs
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*
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* We do _NOT_ restore: ss, flags, cs, gs, fs, es, ds
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*/
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subl $3*4, %esp # RET-IP + 3 gaps
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pushl %ss # ss
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pushl %esp # points at ss
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addl $5*4, (%esp) # make it point at <previous context>
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pushfl # flags
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pushl $__KERNEL_CS # cs
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pushl 7*4(%esp) # ip <- RET-IP
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pushl $0 # orig_eax
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pushl %gs
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pushl %fs
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pushl %es
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pushl %ds
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pushl %eax
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pushl %ebp
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pushl %edi
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pushl %esi
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pushl %edx
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pushl %ecx
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pushl %ebx
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ENCODE_FRAME_POINTER
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movl PT_EIP(%esp), %eax # 1st argument: IP
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subl $MCOUNT_INSN_SIZE, %eax
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movl 21*4(%esp), %edx # 2nd argument: parent ip
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movl function_trace_op, %ecx # 3rd argument: ftrace_pos
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pushl %esp # 4th argument: pt_regs
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GLOBAL(ftrace_regs_call)
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call ftrace_stub
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addl $4, %esp # skip 4th argument
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/* place IP below the new SP */
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movl PT_OLDESP(%esp), %eax
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movl PT_EIP(%esp), %ecx
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movl %ecx, -4(%eax)
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/* place EAX below that */
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movl PT_EAX(%esp), %ecx
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movl %ecx, -8(%eax)
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popl %ebx
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popl %ecx
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popl %edx
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popl %esi
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popl %edi
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popl %ebp
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lea -8(%eax), %esp
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popl %eax
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jmp .Lftrace_ret
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#ifdef CONFIG_FUNCTION_GRAPH_TRACER
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ENTRY(ftrace_graph_caller)
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pushl %eax
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pushl %ecx
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pushl %edx
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movl 3*4(%esp), %eax
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/* Even with frame pointers, fentry doesn't have one here */
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lea 4*4(%esp), %edx
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movl $0, %ecx
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subl $MCOUNT_INSN_SIZE, %eax
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call prepare_ftrace_return
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popl %edx
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popl %ecx
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popl %eax
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ret
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END(ftrace_graph_caller)
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.globl return_to_handler
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return_to_handler:
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pushl %eax
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pushl %edx
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movl $0, %eax
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call ftrace_return_to_handler
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movl %eax, %ecx
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popl %edx
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popl %eax
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JMP_NOSPEC %ecx
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#endif
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