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Re: [ARM] getcontext routines v2
On 28/02/12 12:05, Carlos O'Donell wrote:
On Mon, Feb 27, 2012 at 5:03 PM, Michael Hope<michael.hope@linaro.org> wrote:
I looked over things briefly and the formatting and license looks OK.
Do you and Dave have FSF copyright assignments in place?
Yes. Linaro has an assignment agreement for GCC, GDB, binutils, and GLIBC
under case #664398.
Excellent. Thanks.
(1) Is setcontext correctly implemented?
It's correct to the specification and matches the MIPS and Tile ports. From
IEEE 1003.1:2004:
I've gone and re-read the standard, and I agree with you.
Personally I think there is a QoI issue here, but you meet the
standard which is the right thing to do.
Agreed. Being able to change uc_link while in a makecontext() child would be nice.
+++ b/sysdeps/unix/sysv/linux/arm/eabi/getcontext.S
@@ -0,0 +1,114 @@
+/* Copyright (C) 2012 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, write to the Free
+ Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+ 02111-1307 USA. */
+
This should be:
~~~
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
~~~
We don't use the address form of the license.
Please repost the patch with the license change and I'll check it in.
Updated to match the recent MIPS commits.
-- Michael
diff --git a/ChangeLog.arm b/ChangeLog.arm
index 9eef7e7..7ecb11b 100644
--- a/ChangeLog.arm
+++ b/ChangeLog.arm
@@ -1,3 +1,13 @@
+2012-02-27 Michael Hope <michael.hope@linaro.org>
+
+ * sysdeps/unix/sysv/linux/arm/eabi/getcontext.S: New file.
+ * sysdeps/unix/sysv/linux/arm/eabi/makecontext.c: New file.
+ * sysdeps/unix/sysv/linux/arm/eabi/setcontext.S: New file.
+ * sysdeps/unix/sysv/linux/arm/eabi/swapcontext.S: New file.
+ * sysdeps/unix/sysv/linux/arm/ucontext_i.sym: New file.
+ * sysdeps/unix/sysv/linux/arm/Makefile (gen-as-const-headers): Add
+ ucontext_i.sym.
+
2012-02-17 Aurelien Jarno <aurelien@aurel32.net>
* sysdeps/arm/libm-test-ulps: Adjust ULPs for jn tests.
diff --git a/sysdeps/unix/sysv/linux/arm/Makefile b/sysdeps/unix/sysv/linux/arm/Makefile
index d91b968..a981736 100644
--- a/sysdeps/unix/sysv/linux/arm/Makefile
+++ b/sysdeps/unix/sysv/linux/arm/Makefile
@@ -20,3 +20,7 @@ endif
ifeq ($(subdir),resource)
sysdep_routines += oldgetrlimit64
endif
+
+ifeq ($(subdir),stdlib)
+gen-as-const-headers += ucontext_i.sym
+endif
diff --git a/sysdeps/unix/sysv/linux/arm/eabi/getcontext.S b/sysdeps/unix/sysv/linux/arm/eabi/getcontext.S
new file mode 100644
index 0000000..4266287
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arm/eabi/getcontext.S
@@ -0,0 +1,113 @@
+/* Copyright (C) 2012 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+#include <rtld-global-offsets.h>
+
+#include "ucontext_i.h"
+
+ .syntax unified
+ .text
+
+/* int getcontext (ucontext_t *ucp) */
+
+ENTRY(__getcontext)
+ /* No need to save r0-r3, d0-d7, or d16-d31. */
+ add r1, r0, #MCONTEXT_ARM_R4
+ stmia r1, {r4-r11}
+
+ /* Save R13 separately as Thumb can't STM it. */
+ str r13, [r0, #MCONTEXT_ARM_SP]
+ str r14, [r0, #MCONTEXT_ARM_LR]
+ /* Return to LR */
+ str r14, [r0, #MCONTEXT_ARM_PC]
+ /* Return zero */
+ mov r2, #0
+ str r2, [r0, #MCONTEXT_ARM_R0]
+
+ /* Save ucontext_t * across the next call. */
+ mov r4, r0
+
+ /* __sigprocmask(SIG_BLOCK, NULL, &(ucontext->uc_sigmask)) */
+ mov r0, #SIG_BLOCK
+ mov r1, #0
+ add r2, r4, #UCONTEXT_SIGMASK
+ bl PLTJMP(__sigprocmask)
+
+ /* Store FP regs. Much of the FP code is copied from arm/eabi/setjmp.S. */
+
+#ifdef PIC
+ ldr r2, 1f
+ ldr r1, Lrtld_global_ro
+0: add r2, pc, r2
+ ldr r2, [r2, r1]
+ ldr r2, [r2, #RTLD_GLOBAL_RO_DL_HWCAP_OFFSET]
+#else
+ ldr r2, Lhwcap
+ ldr r2, [r2, #0]
+#endif
+
+ add r0, r4, #UCONTEXT_REGSPACE
+
+ tst r2, #HWCAP_ARM_VFP
+ beq Lno_vfp
+
+ /* Store the VFP registers.
+ Don't use VFP instructions directly because this code
+ is used in non-VFP multilibs. */
+ /* Following instruction is vstmia r0!, {d8-d15}. */
+ stc p11, cr8, [r0], #64
+ /* Store the floating-point status register. */
+ /* Following instruction is vmrs r1, fpscr. */
+ mrc p10, 7, r1, cr1, cr0, 0
+ str r1, [r0], #4
+Lno_vfp:
+
+ tst r2, #HWCAP_ARM_IWMMXT
+ beq Lno_iwmmxt
+
+ /* Save the call-preserved iWMMXt registers. */
+ /* Following instructions are wstrd wr10, [r0], #8 (etc.) */
+ stcl p1, cr10, [r0], #8
+ stcl p1, cr11, [r0], #8
+ stcl p1, cr12, [r0], #8
+ stcl p1, cr13, [r0], #8
+ stcl p1, cr14, [r0], #8
+ stcl p1, cr15, [r0], #8
+Lno_iwmmxt:
+
+ /* Restore the clobbered R4 and LR. */
+ ldr r14, [r4, #MCONTEXT_ARM_LR]
+ ldr r4, [r4, #MCONTEXT_ARM_R4]
+
+ mov r0, #0
+
+ DO_RET(r14)
+
+END(__getcontext)
+
+#ifdef PIC
+1: .long _GLOBAL_OFFSET_TABLE_ - 0b - 8
+Lrtld_global_ro:
+ .long C_SYMBOL_NAME(_rtld_global_ro)(GOT)
+#else
+Lhwcap:
+ .long C_SYMBOL_NAME(_dl_hwcap)
+#endif
+
+
+weak_alias(__getcontext, getcontext)
diff --git a/sysdeps/unix/sysv/linux/arm/eabi/makecontext.c b/sysdeps/unix/sysv/linux/arm/eabi/makecontext.c
new file mode 100644
index 0000000..d6ae6f0
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arm/eabi/makecontext.c
@@ -0,0 +1,73 @@
+/* Copyright (C) 2012 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <stdarg.h>
+#include <ucontext.h>
+
+/* Number of arguments that go in registers. */
+#define NREG_ARGS 4
+
+/* Take a context previously prepared via getcontext() and set to
+ call func() with the given int only args. */
+void
+__makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...)
+{
+ extern void __startcontext (void);
+ unsigned long *funcstack;
+ va_list vl;
+ unsigned long *regptr;
+ unsigned int reg;
+ int misaligned;
+
+ /* Start at the top of stack. */
+ funcstack = (unsigned long *) (ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
+
+ /* Ensure the stack stays eight byte aligned. */
+ misaligned = ((unsigned long) funcstack & 4) != 0;
+
+ if ((argc > NREG_ARGS) && (argc & 1) != 0)
+ misaligned = !misaligned;
+
+ if (misaligned)
+ funcstack -= 1;
+
+ va_start (vl, argc);
+
+ /* Reserve space for the on-stack arguments. */
+ if (argc > NREG_ARGS)
+ funcstack -= (argc - NREG_ARGS);
+
+ ucp->uc_mcontext.arm_sp = (unsigned long) funcstack;
+ ucp->uc_mcontext.arm_pc = (unsigned long) func;
+
+ /* Exit to startcontext() with the next context in R4 */
+ ucp->uc_mcontext.arm_r4 = (unsigned long) ucp->uc_link;
+ ucp->uc_mcontext.arm_lr = (unsigned long) __startcontext;
+
+ /* The first four arguments go into registers. */
+ regptr = &(ucp->uc_mcontext.arm_r0);
+
+ for (reg = 0; (reg < argc) && (reg < NREG_ARGS); reg++)
+ *regptr++ = va_arg (vl, unsigned long);
+
+ /* And the remainder on the stack. */
+ for (; reg < argc; reg++)
+ *funcstack++ = va_arg (vl, unsigned long);
+
+ va_end (vl);
+}
+weak_alias (__makecontext, makecontext)
diff --git a/sysdeps/unix/sysv/linux/arm/eabi/setcontext.S b/sysdeps/unix/sysv/linux/arm/eabi/setcontext.S
new file mode 100644
index 0000000..78003f5
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arm/eabi/setcontext.S
@@ -0,0 +1,101 @@
+/* Copyright (C) 2012 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+#include <rtld-global-offsets.h>
+
+#include "ucontext_i.h"
+
+ .syntax unified
+ .text
+
+/* int setcontext (const ucontext_t *ucp) */
+
+ENTRY(__setcontext)
+ mov r4, r0
+ add r0, r0, #UCONTEXT_REGSPACE
+
+ /* Restore the VFP registers. Copied from arm/eabi/__longjmp.S. */
+#ifdef PIC
+ ldr r2, 1f
+ ldr r1, Lrtld_global_ro
+0: add r2, pc, r2
+ ldr r2, [r2, r1]
+ ldr r2, [r2, #RTLD_GLOBAL_RO_DL_HWCAP_OFFSET]
+#else
+ ldr r2, Lhwcap
+ ldr r2, [r2, #0]
+#endif
+
+ tst r2, #HWCAP_ARM_VFP
+ beq Lno_vfp_sc
+
+ /* Following instruction is vldmia r0!, {d8-d15}. */
+ ldc p11, cr8, [r0], #64
+ /* Restore the floating-point status register. */
+ ldr r1, [r0], #4
+ /* Following instruction is fmxr fpscr, r1. */
+ mcr p10, 7, r1, cr1, cr0, 0
+Lno_vfp_sc:
+ tst r2, #HWCAP_ARM_IWMMXT
+ beq Lno_iwmmxt_sc
+
+ /* Restore the call-preserved iWMMXt registers. */
+ /* Following instructions are wldrd wr10, [r0], #8 (etc.) */
+ ldcl p1, cr10, [r0], #8
+ ldcl p1, cr11, [r0], #8
+ ldcl p1, cr12, [r0], #8
+ ldcl p1, cr13, [r0], #8
+ ldcl p1, cr14, [r0], #8
+ ldcl p1, cr15, [r0], #8
+Lno_iwmmxt_sc:
+
+ /* Now bring back the signal status. */
+ mov r0, #SIG_SETMASK
+ add r1, r4, #UCONTEXT_SIGMASK
+ mov r2, #0
+ bl PLTJMP(__sigprocmask)
+
+ /* Loading r0-r3 makes makecontext easier. */
+ add r14, r4, #MCONTEXT_ARM_R0
+ ldmia r14, {r0-r12}
+ ldr r13, [r14, #(MCONTEXT_ARM_SP - MCONTEXT_ARM_R0)]
+ add r14, r14, #(MCONTEXT_ARM_LR - MCONTEXT_ARM_R0)
+ ldmia r14, {r14, pc}
+
+END(setcontext)
+weak_alias(__setcontext, setcontext)
+
+ /* Called when a makecontext() context returns. Start the
+ context in R4 or fall through to exit(). */
+ENTRY(__startcontext)
+ movs r0, r4
+ bne PLTJMP(__setcontext)
+
+ @ New context was 0 - exit
+ b PLTJMP(_exit)
+END(__startcontext)
+
+#ifdef PIC
+1: .long _GLOBAL_OFFSET_TABLE_ - 0b - 8
+Lrtld_global_ro:
+ .long C_SYMBOL_NAME(_rtld_global_ro)(GOT)
+#else
+Lhwcap:
+ .long C_SYMBOL_NAME(_dl_hwcap)
+#endif
+
diff --git a/sysdeps/unix/sysv/linux/arm/eabi/swapcontext.S b/sysdeps/unix/sysv/linux/arm/eabi/swapcontext.S
new file mode 100644
index 0000000..09492d0
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arm/eabi/swapcontext.S
@@ -0,0 +1,63 @@
+/* Copyright (C) 2012 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
+ <http://www.gnu.org/licenses/>. */
+
+#include <sysdep.h>
+
+#include "ucontext_i.h"
+
+ .syntax unified
+ .text
+
+/* int swapcontext (ucontext_t *oucp, const ucontext_t *ucp) */
+
+ENTRY(swapcontext)
+
+ /* Have getcontext() do most of the work then fix up
+ LR afterwards. Save R3 to keep the stack aligned. */
+ push {r0,r1,r3,r14}
+ cfi_adjust_cfa_offset (16)
+ cfi_rel_offset (r0,0)
+ cfi_rel_offset (r1,4)
+ cfi_rel_offset (r3,8)
+ cfi_rel_offset (r14,12)
+
+ bl __getcontext
+ mov r4, r0
+
+ pop {r0,r1,r3,r14}
+ cfi_adjust_cfa_offset (-16)
+ cfi_restore (r0)
+ cfi_restore (r1)
+ cfi_restore (r3)
+ cfi_restore (r14)
+
+ /* Exit if getcontext() failed. */
+ cmp r4, #0
+ itt ne
+ movne r0, r4
+ RETINSTR(ne, r14)
+
+ /* Fix up LR and the PC. */
+ str r13,[r0, #MCONTEXT_ARM_SP]
+ str r14,[r0, #MCONTEXT_ARM_LR]
+ str r14,[r0, #MCONTEXT_ARM_PC]
+
+ /* And swap using swapcontext(). */
+ mov r0, r1
+ b __setcontext
+
+END(swapcontext)
diff --git a/sysdeps/unix/sysv/linux/arm/ucontext_i.sym b/sysdeps/unix/sysv/linux/arm/ucontext_i.sym
new file mode 100644
index 0000000..306292f
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/arm/ucontext_i.sym
@@ -0,0 +1,30 @@
+#include <inttypes.h>
+#include <signal.h>
+#include <stddef.h>
+#include <sys/ucontext.h>
+
+SIG_BLOCK
+SIG_SETMASK
+
+-- Offsets of the fields in the ucontext_t structure.
+#define ucontext(member) offsetof (ucontext_t, member)
+#define mcontext(member) ucontext (uc_mcontext.member)
+
+UCONTEXT_FLAGS ucontext (uc_flags)
+UCONTEXT_LINK ucontext (uc_link)
+UCONTEXT_STACK ucontext (uc_stack)
+UCONTEXT_MCONTEXT ucontext (uc_mcontext)
+UCONTEXT_SIGMASK ucontext (uc_sigmask)
+
+UCONTEXT_REGSPACE ucontext (uc_regspace)
+
+MCONTEXT_TRAP_NO mcontext (trap_no)
+MCONTEXT_ERROR_CODE mcontext (error_code)
+MCONTEXT_OLDMASK mcontext (oldmask)
+MCONTEXT_ARM_R0 mcontext (arm_r0)
+MCONTEXT_ARM_R4 mcontext (arm_r4)
+MCONTEXT_ARM_SP mcontext (arm_sp)
+MCONTEXT_ARM_LR mcontext (arm_lr)
+MCONTEXT_ARM_PC mcontext (arm_pc)
+MCONTEXT_ARM_CPSR mcontext (arm_cpsr)
+MCONTEXT_FAULT_ADDRESS mcontext (fault_address)