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| author |   Lai Jiangshan <jiangshan.ljs@antgroup.com> | 2022-04-21 22:10:50 +0800 |
|---|---|---|
| committer |   Borislav Petkov <bp@suse.de> | 2022-05-03 11:42:59 +0200 |
| commit | ee774dac0da1543376a69fd90840af6aa86879b3 (patch) | |
| tree | 386802553f708c4dcfdbc11a66abbeab03584bd0 /arch/x86/entry/entry_64.S | |
| parent | x86/entry: Switch the stack after error_entry() returns (diff) | |
| download | wireguard-linux-ee774dac0da1543376a69fd90840af6aa86879b3.tar.xz wireguard-linux-ee774dac0da1543376a69fd90840af6aa86879b3.zip | |
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
Diffstat (limited to 'arch/x86/entry/entry_64.S')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 15 |
1 files changed, 12 insertions, 3 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index ca3e99e08a44..b1cef3b0a7ab 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -318,6 +318,14 @@ SYM_CODE_END(ret_from_fork) #endif .endm +/* Save all registers in pt_regs */ +SYM_CODE_START_LOCAL(push_and_clear_regs) + UNWIND_HINT_FUNC + PUSH_AND_CLEAR_REGS save_ret=1 + ENCODE_FRAME_POINTER 8 + RET +SYM_CODE_END(push_and_clear_regs) + /** * idtentry_body - Macro to emit code calling the C function * @cfunc: C function to be called @@ -325,6 +333,9 @@ SYM_CODE_END(ret_from_fork) */ .macro idtentry_body cfunc has_error_code:req + call push_and_clear_regs + UNWIND_HINT_REGS + call error_entry movq %rax, %rsp /* switch to the task stack if from userspace */ ENCODE_FRAME_POINTER @@ -985,13 +996,11 @@ SYM_CODE_START_LOCAL(paranoid_exit) SYM_CODE_END(paranoid_exit) /* - * Save all registers in pt_regs, and switch GS if needed. + * Switch GS and CR3 if needed. */ SYM_CODE_START_LOCAL(error_entry) UNWIND_HINT_FUNC cld - PUSH_AND_CLEAR_REGS save_ret=1 - ENCODE_FRAME_POINTER 8 testb $3, CS+8(%rsp) jz .Lerror_kernelspace |