[PATCH v3 2/6] hurd: Implement longjmp for x86_64
Samuel Thibault
samuel.thibault@gnu.org
Sun Apr 30 23:16:28 GMT 2023
Applied, thanks!
Sergey Bugaev, le sam. 29 avril 2023 23:18:18 +0300, a ecrit:
> Checked on x86_64-gnu.
>
> Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
> ---
> I have checked that setjmp/longjmp actually works sucessfully, with both
> __longjmp and ____longjmp_chk. I have not been able to check w/ sigaltstack
> because we don't yet have the proc server and signals.
>
> Changes since v1:
> - drop the separate non-PIC version, we can always use %rip-relative access
> on x86_64, and that's what the compiler generates anyway even with -fno-pic;
> - use "cmpb $0, __libc_tls_initialized(%rip)" over
> "movb __libc_tls_initialized(%rip), %r10b; testb %r10b, %r10b" -- the former
> is what the compiler generates, so better be consistent.
>
> sysdeps/mach/hurd/x86_64/____longjmp_chk.S | 118 +++++++++++++++++++++
> sysdeps/mach/hurd/x86_64/__longjmp.S | 96 +++++++++++++++++
> 2 files changed, 214 insertions(+)
> create mode 100644 sysdeps/mach/hurd/x86_64/____longjmp_chk.S
> create mode 100644 sysdeps/mach/hurd/x86_64/__longjmp.S
>
> diff --git a/sysdeps/mach/hurd/x86_64/____longjmp_chk.S b/sysdeps/mach/hurd/x86_64/____longjmp_chk.S
> new file mode 100644
> index 00000000..935b8575
> --- /dev/null
> +++ b/sysdeps/mach/hurd/x86_64/____longjmp_chk.S
> @@ -0,0 +1,118 @@
> +/* Checked longjmp support. x86_64 Hurd version.
> + Copyright (C) 2001-2023 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <https://www.gnu.org/licenses/>. */
> +
> +#include <sysdep.h>
> +#include <pointer_guard.h>
> +#include <jmpbuf-offsets.h>
> +#include <asm-syntax.h>
> +#include <tcb-offsets.h>
> +#include <jmp_buf-ssp.h>
> +#include <signal-defines.h>
> +
> +#define SS_ONSTACK 1
> +
> +/* Don't restore shadow stack register if shadow stack isn't enabled. */
> +#if !SHSTK_ENABLED
> +# undef SHADOW_STACK_POINTER_OFFSET
> +#endif
> +
> + .section .rodata.str1.1,"aMS",@progbits,1
> + .type longjmp_msg,@object
> +longjmp_msg:
> + .string "longjmp causes uninitialized stack frame"
> + .size longjmp_msg, .-longjmp_msg
> +
> +
> +# define CALL_FAIL sub $8, %RSP_LP; \
> + cfi_remember_state; \
> + cfi_def_cfa_offset(16); \
> + lea longjmp_msg(%rip), %RDI_LP; \
> + call HIDDEN_JUMPTARGET(__fortify_fail); \
> + nop; \
> + cfi_restore_state
> +
> +/* Jump to the position specified by ENV, causing the
> + setjmp call there to return VAL, or 1 if VAL is 0.
> + void __longjmp (__jmp_buf env, int val). */
> + .text
> +ENTRY(____longjmp_chk)
> + /* Restore registers. */
> + mov (JB_RSP*8)(%rdi), %R8_LP
> + mov (JB_RBP*8)(%rdi),%R9_LP
> + mov (JB_PC*8)(%rdi), %RDX_LP
> +#ifdef PTR_DEMANGLE
> + PTR_DEMANGLE (%R8_LP)
> + PTR_DEMANGLE (%R9_LP)
> + PTR_DEMANGLE (%RDX_LP)
> +#endif
> +
> +#if !defined (SHARED) || IS_IN (rtld)
> + cmpb $0, __libc_tls_initialized(%rip)
> + jz .Lok /* TLS not initialized yet */
> +#endif
> +
> + movq %fs:SIGSTATE_OFFSET, %R10_LP
> + testq %R10_LP, %R10_LP
> + jz .Lok /* sigstate not initialized yet */
> +
> + testl $SS_ONSTACK, (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%R10_LP)
> + jnz .Lonstack
> +
> + /* We were on the main stack. Jumping to a higher-address
> + frame is always allowed, otherwise it's not allowed. */
> + cmp %R8_LP, %RSP_LP
> + jbe .Lok
> +
> +.Lfail: CALL_FAIL
> +
> +.Lonstack:
> + cmpq (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%R10_LP), %R8_LP
> + jb .Loks /* Jumping below the altstack, switch */
> +
> + movq (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%R10_LP), %R11_LP
> + addq (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SIZE__OFFSET)(%R10_LP), %R11_LP
> + cmpq %R11_LP, %R8_LP
> + jb .Lok /* Jumping inside the altstack, do not switch */
> +
> + /* Jumping above the altstack, switch */
> +
> +.Loks:
> + andl $~(SS_ONSTACK), (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%R10_LP)
> +
> +.Lok:
> + /* We add unwind information for the target here. */
> + cfi_def_cfa(%rdi, 0)
> + cfi_register(%rsp,%r8)
> + cfi_register(%rbp,%r9)
> + cfi_register(%rip,%rdx)
> + cfi_offset(%rbx,JB_RBX*8)
> + cfi_offset(%r12,JB_R12*8)
> + cfi_offset(%r13,JB_R13*8)
> + cfi_offset(%r14,JB_R14*8)
> + cfi_offset(%r15,JB_R15*8)
> + movq (JB_RBX*8)(%rdi), %rbx
> + movq (JB_R12*8)(%rdi), %r12
> + movq (JB_R13*8)(%rdi), %r13
> + movq (JB_R14*8)(%rdi), %r14
> + movq (JB_R15*8)(%rdi), %r15
> + /* Set return value for setjmp. */
> + movl %esi, %eax
> + mov %R8_LP, %RSP_LP
> + movq %r9,%rbp
> + jmpq *%rdx
> +END (____longjmp_chk)
> diff --git a/sysdeps/mach/hurd/x86_64/__longjmp.S b/sysdeps/mach/hurd/x86_64/__longjmp.S
> new file mode 100644
> index 00000000..389c1d16
> --- /dev/null
> +++ b/sysdeps/mach/hurd/x86_64/__longjmp.S
> @@ -0,0 +1,96 @@
> +/* longjmp support. x86_64/Hurd version.
> + Copyright (C) 2001-2023 Free Software Foundation, Inc.
> + This file is part of the GNU C Library.
> +
> + The GNU C Library is free software; you can redistribute it and/or
> + modify it under the terms of the GNU Lesser General Public
> + License as published by the Free Software Foundation; either
> + version 2.1 of the License, or (at your option) any later version.
> +
> + The GNU C Library is distributed in the hope that it will be useful,
> + but WITHOUT ANY WARRANTY; without even the implied warranty of
> + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + Lesser General Public License for more details.
> +
> + You should have received a copy of the GNU Lesser General Public
> + License along with the GNU C Library; if not, see
> + <https://www.gnu.org/licenses/>. */
> +
> +#include <sysdep.h>
> +#include <pointer_guard.h>
> +#include <jmpbuf-offsets.h>
> +#include <asm-syntax.h>
> +#include <tcb-offsets.h>
> +#include <jmp_buf-ssp.h>
> +#include <signal-defines.h>
> +
> +#define SS_ONSTACK 1
> +
> +/* Don't restore shadow stack register if shadow stack isn't enabled. */
> +#if !SHSTK_ENABLED
> +# undef SHADOW_STACK_POINTER_OFFSET
> +#endif
> +
> +/* Jump to the position specified by ENV, causing the
> + setjmp call there to return VAL, or 1 if VAL is 0.
> + void __longjmp (__jmp_buf env, int val). */
> + .text
> +ENTRY(__longjmp)
> + /* Restore registers. */
> + mov (JB_RSP*8)(%rdi), %R8_LP
> + mov (JB_RBP*8)(%rdi),%R9_LP
> + mov (JB_PC*8)(%rdi), %RDX_LP
> +#ifdef PTR_DEMANGLE
> + PTR_DEMANGLE (%R8_LP)
> + PTR_DEMANGLE (%R9_LP)
> + PTR_DEMANGLE (%RDX_LP)
> +#endif
> +
> +#if !defined (SHARED) || IS_IN (rtld)
> + cmpb $0, __libc_tls_initialized(%rip)
> + jz .Lok /* TLS not initialized yet */
> +#endif
> +
> + movq %fs:SIGSTATE_OFFSET, %R10_LP
> + testq %R10_LP, %R10_LP
> + jz .Lok /* sigstate not initialized yet */
> +
> + testl $SS_ONSTACK, (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%R10_LP)
> + jz .Lok
> +
> +.Lonstack:
> + cmpq (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%R10_LP), %R8_LP
> + jb .Loks /* Jumping below the altstack, switch */
> +
> + movq (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%R10_LP), %R11_LP
> + addq (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SIZE__OFFSET)(%R10_LP), %R11_LP
> + cmpq %R11_LP, %R8_LP
> + jb .Lok /* Jumping inside the altstack, do not switch */
> +
> + /* Jumping above the altstack, switch */
> +
> +.Loks:
> + andl $~(SS_ONSTACK), (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%R10_LP)
> +
> +.Lok:
> + /* We add unwind information for the target here. */
> + cfi_def_cfa(%rdi, 0)
> + cfi_register(%rsp,%r8)
> + cfi_register(%rbp,%r9)
> + cfi_register(%rip,%rdx)
> + cfi_offset(%rbx,JB_RBX*8)
> + cfi_offset(%r12,JB_R12*8)
> + cfi_offset(%r13,JB_R13*8)
> + cfi_offset(%r14,JB_R14*8)
> + cfi_offset(%r15,JB_R15*8)
> + movq (JB_RBX*8)(%rdi), %rbx
> + movq (JB_R12*8)(%rdi), %r12
> + movq (JB_R13*8)(%rdi), %r13
> + movq (JB_R14*8)(%rdi), %r14
> + movq (JB_R15*8)(%rdi), %r15
> + /* Set return value for setjmp. */
> + movl %esi, %eax
> + mov %R8_LP, %RSP_LP
> + movq %r9,%rbp
> + jmpq *%rdx
> +END (__longjmp)
> --
> 2.40.1
>
--
Samuel
---
Pour une évaluation indépendante, transparente et rigoureuse !
Je soutiens la Commission d'Évaluation de l'Inria.
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