mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-21 02:36:49 +07:00
cc1ac9c792
Currently objtool cannot understand retpolines, and thus cannot generate ORC unwind information for them. This means that we cannot unwind from the middle of a retpoline. The recent ANNOTATE_INTRA_FUNCTION_CALL and UNWIND_HINT_RET_OFFSET support in objtool enables it to understand the basic retpoline construct. A further problem is that the ORC unwind information is alternative invariant; IOW. every alternative should have the same ORC, retpolines obviously violate this. This means we need to out-of-line them. Since all GCC generated code already uses out-of-line retpolines, this should not affect performance much, if anything. This will enable objtool to generate valid ORC data for the out-of-line copies, which means we can correctly and reliably unwind through a retpoline. Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> Link: https://lkml.kernel.org/r/20200428191700.210835357@infradead.org
64 lines
1.6 KiB
ArmAsm
64 lines
1.6 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
|
|
|
|
#include <linux/stringify.h>
|
|
#include <linux/linkage.h>
|
|
#include <asm/dwarf2.h>
|
|
#include <asm/cpufeatures.h>
|
|
#include <asm/alternative-asm.h>
|
|
#include <asm/export.h>
|
|
#include <asm/nospec-branch.h>
|
|
#include <asm/unwind_hints.h>
|
|
#include <asm/frame.h>
|
|
|
|
.macro THUNK reg
|
|
.section .text.__x86.indirect_thunk
|
|
|
|
.align 32
|
|
SYM_FUNC_START(__x86_indirect_thunk_\reg)
|
|
JMP_NOSPEC \reg
|
|
SYM_FUNC_END(__x86_indirect_thunk_\reg)
|
|
|
|
SYM_FUNC_START_NOALIGN(__x86_retpoline_\reg)
|
|
ANNOTATE_INTRA_FUNCTION_CALL
|
|
call .Ldo_rop_\@
|
|
.Lspec_trap_\@:
|
|
UNWIND_HINT_EMPTY
|
|
pause
|
|
lfence
|
|
jmp .Lspec_trap_\@
|
|
.Ldo_rop_\@:
|
|
mov %\reg, (%_ASM_SP)
|
|
UNWIND_HINT_RET_OFFSET
|
|
ret
|
|
SYM_FUNC_END(__x86_retpoline_\reg)
|
|
|
|
.endm
|
|
|
|
/*
|
|
* Despite being an assembler file we can't just use .irp here
|
|
* because __KSYM_DEPS__ only uses the C preprocessor and would
|
|
* only see one instance of "__x86_indirect_thunk_\reg" rather
|
|
* than one per register with the correct names. So we do it
|
|
* the simple and nasty way...
|
|
*
|
|
* Worse, you can only have a single EXPORT_SYMBOL per line,
|
|
* and CPP can't insert newlines, so we have to repeat everything
|
|
* at least twice.
|
|
*/
|
|
|
|
#define __EXPORT_THUNK(sym) _ASM_NOKPROBE(sym); EXPORT_SYMBOL(sym)
|
|
#define EXPORT_THUNK(reg) __EXPORT_THUNK(__x86_indirect_thunk_ ## reg)
|
|
#define EXPORT_RETPOLINE(reg) __EXPORT_THUNK(__x86_retpoline_ ## reg)
|
|
|
|
#undef GEN
|
|
#define GEN(reg) THUNK reg
|
|
#include <asm/GEN-for-each-reg.h>
|
|
|
|
#undef GEN
|
|
#define GEN(reg) EXPORT_THUNK(reg)
|
|
#include <asm/GEN-for-each-reg.h>
|
|
|
|
#undef GEN
|
|
#define GEN(reg) EXPORT_RETPOLINE(reg)
|
|
#include <asm/GEN-for-each-reg.h>
|