Messages in this thread Patch in this message | | | From | Denys Vlasenko <> | Subject | [PATCH 3/4] x86: open-code register save/restore in trace_hardirqs thunks | Date | Thu, 8 Jan 2015 17:25:14 +0100 |
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This is a preparatory patch for change in "struct pt_regs" handling in entry_64.S.
trace_hardirqs thunks were (ab)using a part of pt_regs handling code, namely SAVE_ARGS/RESTORE_ARGS macros, to save/restore registers across C function calls.
Since SAVE_ARGS is going to be changed, open-code register saving/restoring here.
Incidentally, this removes a bit of dead code: one SAVE_ARGS was used just to emit a CFI annotation, but it also generated unreachable assembly insns.
Signed-off-by: Denys Vlasenko <dvlasenk@redhat.com> CC: Linus Torvalds <torvalds@linux-foundation.org> CC: Oleg Nesterov <oleg@redhat.com> CC: "H. Peter Anvin" <hpa@zytor.com> CC: Andy Lutomirski <luto@amacapital.net> CC: Frederic Weisbecker <fweisbec@gmail.com> CC: X86 ML <x86@kernel.org> CC: Alexei Starovoitov <ast@plumgrid.com> CC: Will Drewry <wad@chromium.org> CC: Kees Cook <keescook@chromium.org> CC: linux-kernel@vger.kernel.org --- arch/x86/lib/thunk_64.S | 29 ++++++++++++++++++++++++----- 1 file changed, 24 insertions(+), 5 deletions(-)
diff --git a/arch/x86/lib/thunk_64.S b/arch/x86/lib/thunk_64.S index b30b5eb..03a3883 100644 --- a/arch/x86/lib/thunk_64.S +++ b/arch/x86/lib/thunk_64.S @@ -16,10 +16,20 @@ \name: CFI_STARTPROC - /* this one pushes 9 elems, the next one would be %rIP */ - SAVE_ARGS + subq $9*8, %rsp + CFI_ADJUST_CFA_OFFSET 9*8 + movq_cfi r11, 0*8 + movq_cfi r10, 1*8 + movq_cfi r9, 2*8 + movq_cfi r8, 3*8 + movq_cfi rax, 4*8 + movq_cfi rcx, 5*8 + movq_cfi rdx, 6*8 + movq_cfi rsi, 7*8 + movq_cfi rdi, 8*8 .if \put_ret_addr_in_rdi + /* 9*8(%rsp) is return addr on stack */ movq_cfi_restore 9*8, rdi .endif @@ -45,11 +55,20 @@ #endif #endif - /* SAVE_ARGS below is used only for the .cfi directives it contains. */ CFI_STARTPROC - SAVE_ARGS + CFI_ADJUST_CFA_OFFSET 9*8 restore: - RESTORE_ARGS + movq_cfi_restore 0*8, r11 + movq_cfi_restore 1*8, r10 + movq_cfi_restore 2*8, r9 + movq_cfi_restore 3*8, r8 + movq_cfi_restore 4*8, rax + movq_cfi_restore 5*8, rcx + movq_cfi_restore 6*8, rdx + movq_cfi_restore 7*8, rsi + movq_cfi_restore 8*8, rdi + addq 9*8, %rsp + CFI_ADJUST_CFA_OFFSET -9*8 ret CFI_ENDPROC _ASM_NOKPROBE(restore) -- 1.8.1.4
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