meson: support building docs

Toggleable with -Ddocs=(true|false), defaults to false.

Requires bumping minimum meson version to 0.59.0, or 0.61.0 to also
include symlinks.

Makefile

@@ -17,9 +17,13 @@ ifeq ($(ARCH),$(filter $(ARCH),arm64))
 	override ARCH = aarch64
 endif
 
-LIBDIR := /lib
-INCLUDEDIR := /usr/include
-PKGCONFIGDIR := /usr/lib/pkgconfig
+prefix = /usr
+libdir = ${prefix}/lib
+shared_libdir = ${libdir}
+static_libdir = ${libdir}
+includedir = ${prefix}/include
+pkgconfigdir = ${prefix}/lib/pkgconfig
+
 CFLAGS ?= -ggdb3 -O2 -Wall
 CPPFLAGS := -Iinclude -Iarch/${ARCH} -Iarch/common
 ifneq ($(shell uname),Darwin)
@@ -35,6 +39,18 @@ ifeq ($(FREESTANDING),yes)
 	EXPORT_UNPREFIXED = no
 endif
 
+FORCE_SOFT_FLOAT := no
+
+ifeq ($(FORCE_SOFT_FLOAT),yes)
+        CPPFLAGS += -DFORCE_SOFT_FLOAT
+endif
+
+FORCE_HARD_FLOAT := no
+
+ifeq ($(FORCE_HARD_FLOAT),yes)
+        CPPFLAGS += -DFORCE_HARD_FLOAT
+endif
+
 ifeq ($(EXPORT_UNPREFIXED),yes)
 	CPPFLAGS += -DEXPORT_UNPREFIXED
 endif
@@ -67,8 +83,8 @@ else
 endif
 LIBUCONTEXT_STATIC_NAME = libucontext.a
 LIBUCONTEXT_PC = libucontext.pc
-LIBUCONTEXT_PATH = ${LIBDIR}/${LIBUCONTEXT_SONAME}
-LIBUCONTEXT_STATIC_PATH = ${LIBDIR}/${LIBUCONTEXT_STATIC_NAME}
+LIBUCONTEXT_PATH = ${shared_libdir}/${LIBUCONTEXT_SONAME}
+LIBUCONTEXT_STATIC_PATH = ${static_libdir}/${LIBUCONTEXT_STATIC_NAME}
 LIBUCONTEXT_HEADERS = \
 	include/libucontext/libucontext.h \
 	include/libucontext/bits.h
@@ -77,8 +93,8 @@ LIBUCONTEXT_EXAMPLES = \
 LIBUCONTEXT_POSIX_STATIC_NAME = libucontext_posix.a
 LIBUCONTEXT_POSIX_C_SRC = libucontext_posix.c
 LIBUCONTEXT_POSIX_OBJ = ${LIBUCONTEXT_POSIX_C_SRC:.c=.o}
-LIBUCONTEXT_POSIX_PATH = ${LIBDIR}/${LIBUCONTEXT_POSIX_SONAME}
-LIBUCONTEXT_POSIX_STATIC_PATH = ${LIBDIR}/${LIBUCONTEXT_POSIX_STATIC_NAME}
+LIBUCONTEXT_POSIX_PATH = ${shared_libdir}/${LIBUCONTEXT_POSIX_SONAME}
+LIBUCONTEXT_POSIX_STATIC_PATH = ${static_libdir}/${LIBUCONTEXT_POSIX_STATIC_NAME}
 
 ifeq ($(FREESTANDING),yes)
 	LIBUCONTEXT_POSIX_NAME =
@@ -107,8 +123,9 @@ ${LIBUCONTEXT_SONAME}: ${LIBUCONTEXT_NAME}
 
 ${LIBUCONTEXT_PC}: libucontext.pc.in
 	sed -e s:@LIBUCONTEXT_VERSION@:${LIBUCONTEXT_VERSION}:g \
-	    -e s:@LIBUCONTEXT_LIBDIR@:${LIBDIR}:g \
-	    -e s:@LIBUCONTEXT_INCLUDEDIR@:${INCLUDEDIR}:g $< > $@
+	    -e s:@LIBUCONTEXT_SHARED_LIBDIR@:${shared_libdir}:g \
+	    -e s:@LIBUCONTEXT_STATIC_LIBDIR@:${static_libdir}:g \
+	    -e s:@LIBUCONTEXT_INCLUDEDIR@:${includedir}:g $< > $@
 
 MANPAGES_SYMLINKS_3 = \
 	libucontext_getcontext.3 \
@@ -192,13 +209,13 @@ clean: docs_clean
 install: all
 	install -D -m755 ${LIBUCONTEXT_NAME} ${DESTDIR}${LIBUCONTEXT_PATH}
 	install -D -m664 ${LIBUCONTEXT_STATIC_NAME} ${DESTDIR}${LIBUCONTEXT_STATIC_PATH}
-	ln -sf ${LIBUCONTEXT_SONAME} ${DESTDIR}${LIBDIR}/${LIBUCONTEXT_NAME}
+	ln -sf ${LIBUCONTEXT_SONAME} ${DESTDIR}${shared_libdir}/${LIBUCONTEXT_NAME}
 	for i in ${LIBUCONTEXT_HEADERS}; do \
 		destfn=$$(echo $$i | sed s:include/::g); \
-		install -D -m644 $$i ${DESTDIR}${INCLUDEDIR}/$$destfn; \
+		install -D -m644 $$i ${DESTDIR}${includedir}/$$destfn; \
 	done
-	install -D -m644 ${LIBUCONTEXT_PC} ${DESTDIR}${PKGCONFIGDIR}/${LIBUCONTEXT_PC}
-	if [ -n ${LIBUCONTEXT_POSIX_NAME} ]; then \
+	install -D -m644 ${LIBUCONTEXT_PC} ${DESTDIR}${pkgconfigdir}/${LIBUCONTEXT_PC}
+	if [ -n "${LIBUCONTEXT_POSIX_NAME}" ]; then \
 		install -D -m755 ${LIBUCONTEXT_POSIX_NAME} ${DESTDIR}${LIBUCONTEXT_POSIX_PATH}; \
 		install -D -m644 ${LIBUCONTEXT_POSIX_STATIC_NAME} ${DESTDIR}${LIBUCONTEXT_POSIX_STATIC_PATH}; \
 	fi

README.md

@@ -101,4 +101,5 @@ ucontext functions:
   save/restore FPU registers or vector registers may be added in a later release as a build-time
   setting -- for now, we assume a soft-float ABI with no optional processor features.  In practice, this
   does not really matter, code using these functions are unlikely to be impacted by this design
-  assumption.
+  assumption. This is a work in progress, as newer compilers will spill even non-floating-point state
+  through floating point registers when allowed to do so.

arch/arm/defs.h

@@ -2,8 +2,10 @@
 
 #define REG_SZ		(4)
 #define MCONTEXT_GREGS	(32)
+#define VFP_MAGIC_OFFSET (232)
+#define VFP_D8_OFFSET (304)
 
-#define TYPE(__proc)
+#define TYPE(__proc)	.type	__proc, %function;
 
 #define FETCH_LINKPTR(dest) \
 	asm("movs    %0, r4" : "=r" ((dest)))

arch/arm/getcontext.S

@@ -22,6 +22,27 @@ FUNC(libucontext_getcontext)
 	str	r13, [r0, #REG_OFFSET(13)]
 	str	r14, [r0, #REG_OFFSET(15)]
 
+#ifndef FORCE_SOFT_FLOAT
+#ifndef FORCE_HARD_FLOAT
+        /* test for vfp, set kernel-defined magic number in uc_regspace */
+        push    {r0-r1,fp,lr}
+        mov     r0, #16
+        bl      getauxval
+        tst     r0, #64
+        pop     {r0-r1,fp,lr}
+	moveq	r2, #0
+	ldrne	r2, =#0x56465001
+	str	r2, [r0, #VFP_MAGIC_OFFSET]
+        beq     1f
+#endif
+	/* if vfp detected, save d8-d15 */
+	.fpu	vfp
+	add	r1, r0, #VFP_D8_OFFSET
+	vstmia	r1, {d8-d15}
+	.fpu	softvfp
+1:
+#endif
+
 	/* return 0 */
 	mov	r0, #0
 	mov	pc, lr

arch/arm/include/libucontext/bits.h

@@ -23,6 +23,8 @@ typedef struct libucontext_ucontext {
 	struct libucontext_ucontext *uc_link;
 	libucontext_stack_t uc_stack;
 	libucontext_mcontext_t uc_mcontext;
+	unsigned long uc_sigmask[128 / sizeof(long)];
+	unsigned long long uc_regspace[64];
 } libucontext_ucontext_t;
 
 #endif

arch/arm/setcontext.S

@@ -16,6 +16,22 @@ ALIAS(setcontext, libucontext_setcontext)
 ALIAS(__setcontext, libucontext_setcontext)
 
 FUNC(libucontext_setcontext)
+#ifndef FORCE_SOFT_FLOAT
+#ifndef FORCE_HARD_FLOAT
+	/* test for vfp magic number set by getcontext */
+	ldr	r2, [r0, #VFP_MAGIC_OFFSET]
+	ldr	r3, =#0x56465001
+	cmp	r2, r3
+        bne     1f
+#endif
+	/* if vfp in use, restore d8-d15 from uc_regspace */
+	.fpu	vfp
+	add	r14, r0, #VFP_D8_OFFSET
+	vldmia	r14, {d8-d15}
+	.fpu 	softvfp
+1:
+#endif
+
 	/* copy all of the current registers into the ucontext structure */
 	add	r14, r0, #REG_OFFSET(0)
 	ldmia	r14, {r0-r12}

arch/arm/swapcontext.S

@@ -22,6 +22,26 @@ FUNC(libucontext_swapcontext)
 	str	r13, [r0,#REG_OFFSET(13)]
 	str	r14, [r0,#REG_OFFSET(15)]
 
+#ifndef FORCE_SOFT_FLOAT
+#ifndef FORCE_HARD_FLOAT
+	/* test for vfp magic number, copy to other ucontext */
+	ldr	r3, [r1, #VFP_MAGIC_OFFSET]
+	ldr	r4, =#0x56465001
+	str	r3, [r0, #VFP_MAGIC_OFFSET]
+	cmp	r3, r4
+	bne	1f
+#endif
+	/* if vfp in use, save and restore d8-d15 */
+	.fpu	vfp
+	add	r2, r0, #VFP_D8_OFFSET
+	vstmia	r2, {d8-d15}
+
+	add	r14, r1, #VFP_D8_OFFSET
+	vldmia	r14, {d8-d15}
+	.fpu	softvfp
+1:
+#endif
+
 	/* load new registers from the second ucontext structure */
 	add	r14, r1, #REG_OFFSET(0)
 	ldmia	r14, {r0-r12}

doc/meson.build

@@ -0,0 +1,21 @@
+scdoc = find_program('scdoc', required: true)
+
+custom_target(
+  'libucontext.3',
+  output: 'libucontext.3',
+  input: 'libucontext.scd',
+  command: [ scdoc ],
+  feed: true,
+  capture: true,
+  install: true,
+  install_dir: get_option('mandir') / 'man3'
+)
+
+if meson.version().version_compare('>=0.61.0')
+  foreach link : [ 'get', 'make', 'set', 'swap' ]
+    install_symlink('libucontext_' + link + 'context.3',
+      pointing_to: 'libucontext.3',
+      install_dir: get_option('mandir') / 'man3'
+    )
+  endforeach
+endif

include/libucontext/libucontext.h

@@ -4,9 +4,17 @@
 #include <stddef.h>
 #include <libucontext/bits.h>
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 int  libucontext_getcontext(libucontext_ucontext_t *);
 void libucontext_makecontext(libucontext_ucontext_t *, void (*)(), int, ...);
 int  libucontext_setcontext(const libucontext_ucontext_t *);
 int  libucontext_swapcontext(libucontext_ucontext_t *, const libucontext_ucontext_t *);
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif

libucontext.pc.in

@@ -1,8 +1,9 @@
-libdir=@LIBUCONTEXT_LIBDIR@
+libdir=@LIBUCONTEXT_SHARED_LIBDIR@
+static_libdir=@LIBUCONTEXT_STATIC_LIBDIR@
 includedir=@LIBUCONTEXT_INCLUDEDIR@
 
 Name: libucontext
 Version: @LIBUCONTEXT_VERSION@
 Description: ucontext library implementation (standalone)
-Libs: -L${libdir} -lucontext
+Libs: -L${libdir} -L${static_libdir} -lucontext
 Cflags: -I${includedir}

meson.build

@@ -1,7 +1,7 @@
 project(
   'libucontext',
   'c',
-  meson_version : '>=0.55.0',
+  meson_version : '>=0.59.0',
   default_options: ['c_std=gnu11', 'default_library=both'],
   version : run_command('head', files('VERSION')).stdout()
 )
@@ -144,9 +144,8 @@ endif
 # Docs
 # ====
 
-# TODO: meson.build for docs
-if not meson.is_subproject()
-  #subdir('docs')
+if not meson.is_subproject() and get_option('docs')
+  subdir('doc')
 endif
 
 # ==========

meson_options.txt

@@ -4,3 +4,5 @@ option('export_unprefixed', type : 'boolean', value : true,
        description: 'Export POSIX 2004 ucontext names as alises')
 option('cpu', type : 'string', value : '',
        description: 'Target CPU architecture for cross compile')
+option('docs', type : 'boolean', value : false,
+       description: 'Build and install man pages')