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x86/entry: Move PUSH_AND_CLEAR_REGS out of error_entry()
The macro idtentry() (through idtentry_body()) calls error_entry() unconditionally even on XENPV. But XENPV needs to only push and clear regs. PUSH_AND_CLEAR_REGS in error_entry() makes the stack not return to its original place when the function returns, which means it is not possible to convert it to a C function. Carve out PUSH_AND_CLEAR_REGS out of error_entry() and into a separate function and call it before error_entry() in order to avoid calling error_entry() on XENPV. It will also allow for error_entry() to be converted to C code that can use inlined sync_regs() and save a function call. [ bp: Massage commit message. ] Signed-off-by: Lai Jiangshan <jiangshan.ljs@antgroup.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Juergen Gross <jgross@suse.com> Link: https://lore.kernel.org/r/20220503032107.680190-4-jiangshanlai@gmail.com
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1 changed files with 12 additions and 3 deletions
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@ -318,6 +318,14 @@ SYM_CODE_END(ret_from_fork)
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#endif
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#endif
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.endm
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.endm
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/* Save all registers in pt_regs */
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SYM_CODE_START_LOCAL(push_and_clear_regs)
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UNWIND_HINT_FUNC
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PUSH_AND_CLEAR_REGS save_ret=1
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ENCODE_FRAME_POINTER 8
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RET
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SYM_CODE_END(push_and_clear_regs)
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/**
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/**
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* idtentry_body - Macro to emit code calling the C function
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* idtentry_body - Macro to emit code calling the C function
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* @cfunc: C function to be called
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* @cfunc: C function to be called
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@ -325,6 +333,9 @@ SYM_CODE_END(ret_from_fork)
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*/
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*/
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.macro idtentry_body cfunc has_error_code:req
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.macro idtentry_body cfunc has_error_code:req
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call push_and_clear_regs
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UNWIND_HINT_REGS
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call error_entry
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call error_entry
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movq %rax, %rsp /* switch to the task stack if from userspace */
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movq %rax, %rsp /* switch to the task stack if from userspace */
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ENCODE_FRAME_POINTER
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ENCODE_FRAME_POINTER
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@ -985,13 +996,11 @@ SYM_CODE_START_LOCAL(paranoid_exit)
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SYM_CODE_END(paranoid_exit)
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SYM_CODE_END(paranoid_exit)
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/*
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/*
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* Save all registers in pt_regs, and switch GS if needed.
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* Switch GS and CR3 if needed.
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*/
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*/
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SYM_CODE_START_LOCAL(error_entry)
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SYM_CODE_START_LOCAL(error_entry)
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UNWIND_HINT_FUNC
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UNWIND_HINT_FUNC
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cld
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cld
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PUSH_AND_CLEAR_REGS save_ret=1
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ENCODE_FRAME_POINTER 8
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testb $3, CS+8(%rsp)
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testb $3, CS+8(%rsp)
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jz .Lerror_kernelspace
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jz .Lerror_kernelspace
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