hurd: fix clearing SS_ONSTACK when longjmp-ing from sighandler

* sysdeps/i386/htl/Makefile: New file.
* sysdeps/i386/htl/tcb-offsets.sym: New file.
* sysdeps/mach/hurd/i386/Makefile [setjmp] (gen-as-const-headers): Add
signal-defines.sym.
* sysdeps/mach/hurd/i386/____longjmp_chk.S: Include tcb-offsets.h.
(____longjmp_chk): Harmonize with i386's __longjmp. Clear SS_ONSTACK
when jumping off the alternate stack.
* sysdeps/mach/hurd/i386/__longjmp.S: New file.

5 files changed, 154 insertions, 32 deletions

diff --git a/sysdeps/i386/htl/Makefile b/sysdeps/i386/htl/Makefile
new file mode 100644
index 0000000000..8573ce6990
--- /dev/null
+++ b/sysdeps/i386/htl/Makefile
@@ -0,0 +1,20 @@
+# Copyright (C) 2020 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/>.
+
+ifeq ($(subdir),csu)
+gen-as-const-headers += tcb-offsets.sym
+endif
diff --git a/sysdeps/i386/htl/tcb-offsets.sym b/sysdeps/i386/htl/tcb-offsets.sym
new file mode 100644
index 0000000000..7b7c719369
--- /dev/null
+++ b/sysdeps/i386/htl/tcb-offsets.sym
@@ -0,0 +1,8 @@
+#include <sysdep.h>
+#include <tls.h>
+#include <kernel-features.h>
+
+MULTIPLE_THREADS_OFFSET offsetof (tcbhead_t, multiple_threads)
+SYSINFO_OFFSET          offsetof (tcbhead_t, sysinfo)
+POINTER_GUARD           offsetof (tcbhead_t, pointer_guard)
+SIGSTATE_OFFSET         offsetof (tcbhead_t, _hurd_sigstate)
diff --git a/sysdeps/mach/hurd/i386/Makefile b/sysdeps/mach/hurd/i386/Makefile
index 068f7d0419..495b927b82 100644
--- a/sysdeps/mach/hurd/i386/Makefile
+++ b/sysdeps/mach/hurd/i386/Makefile
@@ -7,6 +7,10 @@ ifeq ($(subdir),debug)
 gen-as-const-headers += signal-defines.sym
 endif
 
+ifeq ($(subdir),setjmp)
+gen-as-const-headers += signal-defines.sym
+endif
+
 ifeq ($(subdir),csu)
 ifeq (yes,$(build-shared))
 sysdep_routines += divdi3
diff --git a/sysdeps/mach/hurd/i386/____longjmp_chk.S b/sysdeps/mach/hurd/i386/____longjmp_chk.S
index 819e5dc875..4d3a331728 100644
--- a/sysdeps/mach/hurd/i386/____longjmp_chk.S
+++ b/sysdeps/mach/hurd/i386/____longjmp_chk.S
@@ -17,6 +17,7 @@
 
 #include <sysdep.h>
 #include <jmpbuf-offsets.h>
+#include <tcb-offsets.h>
 #include <asm-syntax.h>
 
 #include <signal-defines.h>
@@ -47,65 +48,70 @@ longjmp_msg:
 
 	.text
 ENTRY (____longjmp_chk)
-	movl	4(%esp), %ecx	/* User's jmp_buf in %ecx.  */
+	movl	4(%esp), %eax	/* User's jmp_buf in %eax.  */
 
 	/* Save the return address now.  */
-	movl	(JB_PC*4)(%ecx), %edx
+	movl	(JB_PC*4)(%eax), %edx
 	/* Get the stack pointer.  */
-	movl	(JB_SP*4)(%ecx), %edi
-	cfi_undefined(%edi)
+	movl	(JB_SP*4)(%eax), %ecx
+	cfi_undefined(%ecx)
 #ifdef PTR_DEMANGLE
 	PTR_DEMANGLE (%edx)
-	PTR_DEMANGLE (%edi)
+	PTR_DEMANGLE (%ecx)
 #endif
 
-	cmpl	%edi, %esp
+	movl	%gs:SIGSTATE_OFFSET,%edi
+
+	testl	$SS_ONSTACK, (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%edi)
+	jnz	.Lonstack
+
+	/* We were on the main stack */
+
+	cmpl	%ecx, %esp
 	/* Jumping to a higher-address frame is always allowed.  */
 	jbe	.Lok
 
-	/* Passing here, we're either about to do something invalid, or we're
-	executing on an alternative signal stack.  */
+	/* Otherwise it's not allowed.  */
+	CALL_FAIL
 
-	/* TODO: need locking?  */
-	/* struct hurd_sigstate * _hurd_self_sigstate (void) */
-	call	HIDDEN_JUMPTARGET(_hurd_self_sigstate)
-	/* TODO: %eax and %eax->sigaltstack are always valid?  */
+.Lonstack:
+	/* We were on the alternate stack, can't really easily check anything
+	   since longjmp may get us out of the alternate stack.  */
 
-	testl	$SS_ONSTACK, (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%eax)
-	/* Fail if SS_ONSTACK is not set.  */
-	jz	.Lfail
+	cmpl	(HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%edi), %ecx
+	jb	.Loks		/* We jump below the alternate stack, switch.  */
 
-	movl	(HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%eax), %ebx
-	addl	(HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SIZE__OFFSET)(%eax), %ebx
-	subl	%edi, %ebx
-	cmpl	(HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SIZE__OFFSET)(%eax), %ebx
-	/* TODO: comment this calculation.  */
-	jae	.Lok
+	movl	(HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%edi), %ebx
+	addl	(HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SIZE__OFFSET)(%edi), %ebx
+	cmpl	%ebx, %ecx
+	jb	.Lok		/* We jump inside the alternate stack, do not switch.  */
 
-.Lfail:	CALL_FAIL
+	/* We jump above the alternate stack, switch.  */
+
+.Loks:	/* We jump out of the alternate stack, clear SS_ONSTACK flag.  */
+	andl	$~(SS_ONSTACK), (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%edi)
 
 .Lok:	/* We add unwind information for the target here.  */
-	cfi_def_cfa(%ecx, 0)
+	cfi_def_cfa(%eax, 0)
 	cfi_register(%eip, %edx)
-	cfi_register(%esp, %edi)
+	cfi_register(%esp, %ecx)
 	cfi_offset(%ebx, JB_BX*4)
 	cfi_offset(%esi, JB_SI*4)
 	cfi_offset(%edi, JB_DI*4)
 	cfi_offset(%ebp, JB_BP*4)
-
-	movl	8(%esp), %eax	/* Second argument is return value.  */
-	movl	%edi, %esp
-
 	/* Restore registers.  */
-	movl	(JB_BX*4)(%ecx), %ebx
-	movl	(JB_SI*4)(%ecx), %esi
-	movl	(JB_DI*4)(%ecx), %edi
-	movl	(JB_BP*4)(%ecx), %ebp
+	movl	(JB_BX*4)(%eax), %ebx
+	movl	(JB_SI*4)(%eax), %esi
+	movl	(JB_DI*4)(%eax), %edi
+	movl	(JB_BP*4)(%eax), %ebp
 	cfi_restore(%ebx)
 	cfi_restore(%esi)
 	cfi_restore(%edi)
 	cfi_restore(%ebp)
 
+	movl	8(%esp), %eax	/* Second argument is return value.  */
+	movl	%ecx, %esp
+
 	/* Jump to saved PC.  */
 	jmp	*%edx
 END (____longjmp_chk)
diff --git a/sysdeps/mach/hurd/i386/__longjmp.S b/sysdeps/mach/hurd/i386/__longjmp.S
new file mode 100644
index 0000000000..d123c214c9
--- /dev/null
+++ b/sysdeps/mach/hurd/i386/__longjmp.S
@@ -0,0 +1,84 @@
+/* Copyright (C) 2001-2020 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 <jmpbuf-offsets.h>
+#include <tcb-offsets.h>
+#include <asm-syntax.h>
+
+#include <signal-defines.h>
+/* #include <signal.h> */
+#define SS_ONSTACK 1
+
+	.text
+ENTRY (__longjmp)
+	movl 4(%esp), %eax	/* User's jmp_buf in %eax.  */
+
+	/* Save the return address now.  */
+	movl (JB_PC*4)(%eax), %edx
+	/* Get the stack pointer.  */
+	movl (JB_SP*4)(%eax), %ecx
+	cfi_undefined(%ecx)
+#ifdef PTR_DEMANGLE
+	PTR_DEMANGLE (%edx)
+	PTR_DEMANGLE (%ecx)
+#endif
+
+	movl	%gs:SIGSTATE_OFFSET,%edi
+
+	testl	$SS_ONSTACK, (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%edi)
+	jz	.Lok
+
+	/* We were on the alternate stack.  */
+
+	cmpl	(HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%edi), %ecx
+	jb	.Loks		/* We jump below the alternate stack, switch.  */
+
+	movl	(HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SP__OFFSET)(%edi), %ebx
+	addl	(HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_SIZE__OFFSET)(%edi), %ebx
+	cmpl	%ebx, %ecx
+	jb	.Lok		/* We jump inside the alternate stack, do not switch.  */
+
+	/* We jump above the alternate stack, switch.  */
+
+.Loks:	/* We jump out of the alternate stack, clear SS_ONSTACK flag.  */
+	andl	$~(SS_ONSTACK), (HURD_SIGSTATE__SIGALTSTACK__OFFSET + SIGALTSTACK__SS_FLAGS__OFFSET)(%edi)
+
+.Lok:	/* We add unwind information for the target here.  */
+	cfi_def_cfa(%eax, 0)
+	cfi_register(%eip, %edx)
+	cfi_register(%esp, %ecx)
+	cfi_offset(%ebx, JB_BX*4)
+	cfi_offset(%esi, JB_SI*4)
+	cfi_offset(%edi, JB_DI*4)
+	cfi_offset(%ebp, JB_BP*4)
+	/* Restore registers.  */
+	movl (JB_BX*4)(%eax), %ebx
+	movl (JB_SI*4)(%eax), %esi
+	movl (JB_DI*4)(%eax), %edi
+	movl (JB_BP*4)(%eax), %ebp
+	cfi_restore(%ebx)
+	cfi_restore(%esi)
+	cfi_restore(%edi)
+	cfi_restore(%ebp)
+
+	movl	8(%esp), %eax	/* Second argument is return value.  */
+	movl	%ecx, %esp
+
+	/* Jump to saved PC.  */
+	jmp *%edx
+END (__longjmp)