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Decorate the ARM signal trampoline with the appropriate .cfi 

directives to allow exception unwind / backtrace across a signal
handler.
This commit is contained in:
thorpej 2021-11-23 18:45:53 +00:00
parent 55da09bdbb
commit 389a070437
2 changed files with 60 additions and 16 deletions
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37
lib/libc/arch/arm/genassym.cf
View File

@ -1,4 +1,4 @@
# $NetBSD: genassym.cf,v 1.3 2020/10/24 07:03:11 skrll Exp $
# $NetBSD: genassym.cf,v 1.4 2021/11/23 18:45:53 thorpej Exp $
#
# Copyright (c) 2012 The NetBSD Foundation, Inc.
@ -30,21 +30,30 @@
#
include <sys/types.h>
include <signal.h>
include <ucontext.h>
define _UC_GREGS offsetof(ucontext_t, uc_mcontext.__gregs[0])
define _UC_REGS_R0 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R0])
define _UC_REGS_R1 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R1])
define _UC_REGS_R2 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R2])
define _UC_REGS_R3 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R3])
define _UC_REGS_R4 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R4])
define _UC_REGS_R5 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R5])
define _UC_REGS_R6 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R6])
define _UC_REGS_R7 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R7])
define _UC_REGS_R8 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R8])
define _UC_REGS_R9 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R9])
define _UC_REGS_R10 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R10])
define _UC_REGS_R11 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R11])
define _UC_REGS_R12 offsetof(ucontext_t, uc_mcontext.__gregs[_REG_R12])
define _UC_REGS_SP offsetof(ucontext_t, uc_mcontext.__gregs[_REG_SP])
define _UC_REGS_LR offsetof(ucontext_t, uc_mcontext.__gregs[_REG_LR])
define _UC_REGS_PC offsetof(ucontext_t, uc_mcontext.__gregs[_REG_PC])
define SIZEOF_SIGINFO sizeof(siginfo_t)
define _REG_R0 _REG_R0
define _REG_R1 _REG_R1
define _REG_R2 _REG_R2
define _REG_R3 _REG_R3
define _REG_R4 _REG_R4
define _REG_R5 _REG_R5
define _REG_R6 _REG_R6
define _REG_R7 _REG_R7
define _REG_R8 _REG_R8
define _REG_R9 _REG_R9
define _REG_R10 _REG_R10
define _REG_R11 _REG_R11
define _REG_R12 _REG_R12
define _REG_R13 _REG_R13
define _REG_R14 _REG_R14
define _REG_R15 _REG_R15
define _REG_SP _REG_SP

39
lib/libc/arch/arm/sys/__sigtramp2.S
View File

@ -1,4 +1,4 @@
/* $NetBSD: __sigtramp2.S,v 1.3 2013/08/16 23:20:59 matt Exp $ */
/* $NetBSD: __sigtramp2.S,v 1.4 2021/11/23 18:45:53 thorpej Exp $ */
/*-
* Copyright (c) 2002 The NetBSD Foundation, Inc.
@ -30,6 +30,7 @@
*/
#include "SYS.h"
#include "assym.h"
/*
* The ARM signal trampoline is invoked only to return from
@ -39,12 +40,46 @@
*
* ucontext structure
* sp-> siginfo structure
* and r5 points to the ucontext
* and r5 points to the ucontext
*/
#define CFI_OFFSET(r) .cfi_offset r, r * 4
_TEXT_SECTION
.cfi_startproc
.cfi_signal_frame
.cfi_def_cfa _REG_SP, SIZEOF_SIGINFO + _UC_GREGS
CFI_OFFSET(_REG_R0)
CFI_OFFSET(_REG_R1)
CFI_OFFSET(_REG_R2)
CFI_OFFSET(_REG_R3)
CFI_OFFSET(_REG_R4)
CFI_OFFSET(_REG_R5)
CFI_OFFSET(_REG_R6)
CFI_OFFSET(_REG_R7)
CFI_OFFSET(_REG_R8)
CFI_OFFSET(_REG_R9)
CFI_OFFSET(_REG_R10)
CFI_OFFSET(_REG_R11)
CFI_OFFSET(_REG_R12)
CFI_OFFSET(_REG_R13) /* a.k.a. _REG_SP */
CFI_OFFSET(_REG_R14) /* a.k.a. _REG_LR */
.cfi_return_column _REG_R15
CFI_OFFSET(_REG_R15) /* a.k.a. _REG_PC */
/*
* The unwind entry includes the one instruction prior to the trampoline
* because the unwinder will look up (return PC - 1) while unwinding.
* Normally this would be the jump / branch, but since there isn't one in
* this case, we place an explicit nop there instead.
*/
nop
ENTRY_NP(__sigtramp_siginfo_2)
mov r0, r5 /* set the arg */
SYSTRAP(setcontext) /* and call setcontext */
/* If that failed, exit with the error code. */
SYSTRAP(exit)
.cfi_endproc
END(__sigtramp_siginfo_2)