system/libucontext: fix on ppc64

3 files changed, 442 insertions, 2 deletions

diff --git a/system/libucontext/APKBUILD b/system/libucontext/APKBUILD
index 2adee39f2..f6b020858 100644
--- a/system/libucontext/APKBUILD
+++ b/system/libucontext/APKBUILD
@@ -1,7 +1,7 @@
 # Maintainer: William Pitcock <nenolod@dereferenced.org>
 pkgname=libucontext
 pkgver=0.1.3
-pkgrel=0
+pkgrel=1
 pkgdesc="ucontext function implementations"
 url="https://git.dereferenced.org/kaniini/libucontext/"
 arch="all"
@@ -9,6 +9,8 @@ license="ISC"
 depends=""
 subpackages="$pkgname-dev"
 source="https://distfiles.dereferenced.org/libucontext/libucontext-$pkgver.tar.xz
+	ppc64-assembly.patch
+	ppc64-stack-layout.patch
 	"
 
 case "$CTARGET_ARCH" in
@@ -33,4 +35,6 @@ package() {
 	make ARCH="$LIBUCONTEXT_ARCH" DESTDIR="$pkgdir" install
 }
 
-sha512sums="9e0694c09f159de714b655f6a4201a05c8d1871ee7376bb6bf824206b45475cfbd8269ca1caa75b9c322624d9f77d3fc3f938228a4bdd267a5ddceb57ca5c1ab  libucontext-0.1.3.tar.xz"
+sha512sums="9e0694c09f159de714b655f6a4201a05c8d1871ee7376bb6bf824206b45475cfbd8269ca1caa75b9c322624d9f77d3fc3f938228a4bdd267a5ddceb57ca5c1ab  libucontext-0.1.3.tar.xz
+dbb7599fe5cc1e470d944bf741c393c13e684d6c27bd794ec380a05ba1ba045597b102903a1ac9bf586a508941440373c2d29fad1d7372ee8c72ffb7f0e11f75  ppc64-assembly.patch
+d6219487a5aa456726a01a5a6a39c3a7f29bc24a66f2fc77ff7f852e1b45ffe64854ad92cafad3cc03d3b52bd77dce786ef125e3e88ddb0398833a560afb5211  ppc64-stack-layout.patch"
diff --git a/system/libucontext/ppc64-assembly.patch b/system/libucontext/ppc64-assembly.patch
new file mode 100644
index 000000000..66fb3104d
--- /dev/null
+++ b/system/libucontext/ppc64-assembly.patch
@@ -0,0 +1,331 @@
+From 7b864e86e3e8e64fe69363137384ee9b858fe78d Mon Sep 17 00:00:00 2001
+From: Bobby Bingham <koorogi@koorogi.info>
+Date: Sat, 23 Feb 2019 17:12:37 -0600
+Subject: [PATCH 2/3] ppc64: rewrite get/set/swapcontext in assembly
+
+If getcontext makes any function call, which it does to call syscall, then
+it must spill its return address to the stack.  After it returns to its
+caller, that return address can be clobbered.  When setcontext is called
+to resume this saved context, the correct return address is not available.
+---
+ Makefile                    | 10 ++-------
+ arch/ppc64/getcontext.S     | 25 +++++++++++++++++++++
+ arch/ppc64/getcontext.c     | 45 -------------------------------------
+ arch/ppc64/retfromsyscall.c | 24 ++++++++++++++++++++
+ arch/ppc64/setcontext.S     | 26 +++++++++++++++++++++
+ arch/ppc64/setcontext.c     | 45 -------------------------------------
+ arch/ppc64/swapcontext.S    | 28 +++++++++++++++++++++++
+ arch/ppc64/swapcontext.c    | 45 -------------------------------------
+ 8 files changed, 105 insertions(+), 143 deletions(-)
+ create mode 100644 arch/ppc64/getcontext.S
+ delete mode 100644 arch/ppc64/getcontext.c
+ create mode 100644 arch/ppc64/retfromsyscall.c
+ create mode 100644 arch/ppc64/setcontext.S
+ delete mode 100644 arch/ppc64/setcontext.c
+ create mode 100644 arch/ppc64/swapcontext.S
+ delete mode 100644 arch/ppc64/swapcontext.c
+
+diff --git a/Makefile b/Makefile
+index 51365a3..d6ff1b0 100644
+--- a/Makefile
++++ b/Makefile
+@@ -2,14 +2,8 @@ ARCH := $(shell uname -m)
+ 
+ CFLAGS = -ggdb3 -O2 -Wall -Iarch/${ARCH}
+ 
+-LIBUCONTEXT_C_SRC = \
+-	arch/${ARCH}/makecontext.c
+-
+-LIBUCONTEXT_S_SRC = \
+-	arch/${ARCH}/getcontext.S \
+-	arch/${ARCH}/setcontext.S \
+-	arch/${ARCH}/swapcontext.S \
+-	arch/${ARCH}/startcontext.S
++LIBUCONTEXT_C_SRC = $(wildcard arch/${ARCH}/*.c)
++LIBUCONTEXT_S_SRC = $(wildcard arch/${ARCH}/*.S)
+ 
+ LIBUCONTEXT_OBJ = ${LIBUCONTEXT_C_SRC:.c=.o} ${LIBUCONTEXT_S_SRC:.S=.o}
+ LIBUCONTEXT_SOVERSION = 0
+diff --git a/arch/ppc64/getcontext.S b/arch/ppc64/getcontext.S
+new file mode 100644
+index 0000000..935edd2
+--- /dev/null
++++ b/arch/ppc64/getcontext.S
+@@ -0,0 +1,25 @@
++/*
++ * Copyright (c) 2019 Bobby Bingham <koorogi@koorogi.info>
++ *
++ * Permission to use, copy, modify, and/or distribute this software for any
++ * purpose with or without fee is hereby granted, provided that the above
++ * copyright notice and this permission notice appear in all copies.
++ *
++ * This software is provided 'as is' and without any warranty, express or
++ * implied.  In no event shall the authors be liable for any damages arising
++ * from the use of this software.
++ */
++
++.global __getcontext
++.hidden __swapcontext
++__getcontext:
++	addis 2, 12, .TOC.-__getcontext@ha
++	addi  2, 12, .TOC.-__getcontext@l
++
++	.localentry __getcontext,.-__getcontext
++
++	li 4, 0
++	b __swapcontext
++
++.weak getcontext
++getcontext = __getcontext
+diff --git a/arch/ppc64/getcontext.c b/arch/ppc64/getcontext.c
+deleted file mode 100644
+index 5da9dfb..0000000
+--- a/arch/ppc64/getcontext.c
++++ /dev/null
+@@ -1,45 +0,0 @@
+-/*
+- * Copyright (c) 2018 William Pitcock <nenolod@dereferenced.org>
+- *
+- * Permission to use, copy, modify, and/or distribute this software for any
+- * purpose with or without fee is hereby granted, provided that the above
+- * copyright notice and this permission notice appear in all copies.
+- *
+- * This software is provided 'as is' and without any warranty, express or
+- * implied.  In no event shall the authors be liable for any damages arising
+- * from the use of this software.
+- */
+-
+-#define _GNU_SOURCE
+-#include <stddef.h>
+-#include <stdarg.h>
+-#include <signal.h>
+-#include <string.h>
+-#include <stdint.h>
+-#include <errno.h>
+-#include <unistd.h>
+-#include <sys/syscall.h>
+-
+-
+-int
+-__getcontext(ucontext_t *ucp)
+-{
+-#ifdef SYS_swapcontext
+-	int r;
+-
+-	r = syscall(SYS_swapcontext, ucp, NULL, sizeof(ucontext_t));
+-	if (r < 0)
+-	{
+-		errno = -r;
+-		return -1;
+-	}
+-
+-	return 0;
+-#else
+-	errno = ENOSYS;
+-	return -1;
+-#endif
+-}
+-
+-
+-extern __typeof(__getcontext) getcontext __attribute__((weak, __alias__("__getcontext")));
+diff --git a/arch/ppc64/retfromsyscall.c b/arch/ppc64/retfromsyscall.c
+new file mode 100644
+index 0000000..22c5134
+--- /dev/null
++++ b/arch/ppc64/retfromsyscall.c
+@@ -0,0 +1,24 @@
++/*
++ * Copyright (c) 2019 Bobby Bingham <koorogi@koorogi.info>
++ *
++ * Permission to use, copy, modify, and/or distribute this software for any
++ * purpose with or without fee is hereby granted, provided that the above
++ * copyright notice and this permission notice appear in all copies.
++ *
++ * This software is provided 'as is' and without any warranty, express or
++ * implied.  In no event shall the authors be liable for any damages arising
++ * from the use of this software.
++ */
++
++#include <errno.h>
++
++__attribute__ ((visibility ("hidden")))
++int __retfromsyscall(long retval)
++{
++	if (retval < 0) {
++		errno = -retval;
++		return -1;
++	}
++	return 0;
++}
++
+diff --git a/arch/ppc64/setcontext.S b/arch/ppc64/setcontext.S
+new file mode 100644
+index 0000000..5a0cde3
+--- /dev/null
++++ b/arch/ppc64/setcontext.S
+@@ -0,0 +1,26 @@
++/*
++ * Copyright (c) 2019 Bobby Bingham <koorogi@koorogi.info>
++ *
++ * Permission to use, copy, modify, and/or distribute this software for any
++ * purpose with or without fee is hereby granted, provided that the above
++ * copyright notice and this permission notice appear in all copies.
++ *
++ * This software is provided 'as is' and without any warranty, express or
++ * implied.  In no event shall the authors be liable for any damages arising
++ * from the use of this software.
++ */
++
++.global __setcontext
++.hidden __swapcontext
++__setcontext:
++	addis 2, 12, .TOC.-__setcontext@ha
++	addi  2, 12, .TOC.-__setcontext@l
++
++	.localentry __setcontext,.-__setcontext
++
++	mr 4, 3
++	li 3, 0
++	b __swapcontext
++
++.weak setcontext
++setcontext = __setcontext
+diff --git a/arch/ppc64/setcontext.c b/arch/ppc64/setcontext.c
+deleted file mode 100644
+index 59c65b4..0000000
+--- a/arch/ppc64/setcontext.c
++++ /dev/null
+@@ -1,45 +0,0 @@
+-/*
+- * Copyright (c) 2018 William Pitcock <nenolod@dereferenced.org>
+- *
+- * Permission to use, copy, modify, and/or distribute this software for any
+- * purpose with or without fee is hereby granted, provided that the above
+- * copyright notice and this permission notice appear in all copies.
+- *
+- * This software is provided 'as is' and without any warranty, express or
+- * implied.  In no event shall the authors be liable for any damages arising
+- * from the use of this software.
+- */
+-
+-#define _GNU_SOURCE
+-#include <stddef.h>
+-#include <stdarg.h>
+-#include <signal.h>
+-#include <string.h>
+-#include <stdint.h>
+-#include <errno.h>
+-#include <unistd.h>
+-#include <sys/syscall.h>
+-
+-
+-int
+-__setcontext(const ucontext_t *ucp)
+-{
+-#ifdef SYS_swapcontext
+-	int r;
+-
+-	r = syscall(SYS_swapcontext, NULL, (void *) ucp, sizeof(ucontext_t));
+-	if (r < 0)
+-	{
+-		errno = -r;
+-		return -1;
+-	}
+-
+-	return r;
+-#else
+-	errno = ENOSYS;
+-	return -1;
+-#endif
+-}
+-
+-
+-extern __typeof(__setcontext) setcontext __attribute__((weak, __alias__("__setcontext")));
+diff --git a/arch/ppc64/swapcontext.S b/arch/ppc64/swapcontext.S
+new file mode 100644
+index 0000000..982537a
+--- /dev/null
++++ b/arch/ppc64/swapcontext.S
+@@ -0,0 +1,28 @@
++/*
++ * Copyright (c) 2019 Bobby Bingham <koorogi@koorogi.info>
++ *
++ * Permission to use, copy, modify, and/or distribute this software for any
++ * purpose with or without fee is hereby granted, provided that the above
++ * copyright notice and this permission notice appear in all copies.
++ *
++ * This software is provided 'as is' and without any warranty, express or
++ * implied.  In no event shall the authors be liable for any damages arising
++ * from the use of this software.
++ */
++
++.global __swapcontext
++__swapcontext:
++	addis 2, 12, .TOC.-__swapcontext@ha
++	addi  2, 12, .TOC.-__swapcontext@l
++
++	.localentry __swapcontext,.-__swapcontext
++
++	li 0, 249     # SYS_swapcontext
++	li 5, 1696    # sizeof(ucontext_t)
++	sc
++
++.hidden __retfromsyscall
++	b __retfromsyscall
++
++.weak swapcontext
++swapcontext = __swapcontext
+diff --git a/arch/ppc64/swapcontext.c b/arch/ppc64/swapcontext.c
+deleted file mode 100644
+index af14bc2..0000000
+--- a/arch/ppc64/swapcontext.c
++++ /dev/null
+@@ -1,45 +0,0 @@
+-/*
+- * Copyright (c) 2018 William Pitcock <nenolod@dereferenced.org>
+- *
+- * Permission to use, copy, modify, and/or distribute this software for any
+- * purpose with or without fee is hereby granted, provided that the above
+- * copyright notice and this permission notice appear in all copies.
+- *
+- * This software is provided 'as is' and without any warranty, express or
+- * implied.  In no event shall the authors be liable for any damages arising
+- * from the use of this software.
+- */
+-
+-#define _GNU_SOURCE
+-#include <stddef.h>
+-#include <stdarg.h>
+-#include <signal.h>
+-#include <string.h>
+-#include <stdint.h>
+-#include <errno.h>
+-#include <unistd.h>
+-#include <sys/syscall.h>
+-
+-
+-int
+-__swapcontext(ucontext_t *oucp, const ucontext_t *ucp)
+-{
+-#ifdef SYS_swapcontext
+-	int r;
+-
+-	r = syscall(SYS_swapcontext, oucp, ucp, sizeof(ucontext_t));
+-	if (r < 0)
+-	{
+-		errno = -r;
+-		return -1;
+-	}
+-
+-	return r;
+-#else
+-	errno = ENOSYS;
+-	return -1;
+-#endif
+-}
+-
+-
+-extern __typeof(__swapcontext) swapcontext __attribute__((weak, __alias__("__swapcontext")));
+-- 
+2.19.2
+
diff --git a/system/libucontext/ppc64-stack-layout.patch b/system/libucontext/ppc64-stack-layout.patch
new file mode 100644
index 000000000..d030b61af
--- /dev/null
+++ b/system/libucontext/ppc64-stack-layout.patch
@@ -0,0 +1,105 @@
+From a17b01bc9df4004a1852ba272d452b0f46f5927c Mon Sep 17 00:00:00 2001
+From: Bobby Bingham <koorogi@koorogi.info>
+Date: Tue, 19 Feb 2019 06:27:28 +0000
+Subject: [PATCH 3/3] ppc64: fix stack frame layout
+
+---
+ arch/ppc64/makecontext.c | 48 +++++++++++++++++-----------------------
+ 1 file changed, 20 insertions(+), 28 deletions(-)
+
+diff --git a/arch/ppc64/makecontext.c b/arch/ppc64/makecontext.c
+index 9d6b998..6d9841c 100644
+--- a/arch/ppc64/makecontext.c
++++ b/arch/ppc64/makecontext.c
+@@ -1,5 +1,6 @@
+ /*
+  * Copyright (c) 2018 William Pitcock <nenolod@dereferenced.org>
++ * Copyright (c) 2019 Bobby Bingham <koorogi@koorogi.info>
+  *
+  * Permission to use, copy, modify, and/or distribute this software for any
+  * purpose with or without fee is hereby granted, provided that the above
+@@ -11,32 +12,39 @@
+  */
+ 
+ #define _GNU_SOURCE
+-#include <stddef.h>
+ #include <stdarg.h>
+ #include <signal.h>
+-#include <string.h>
+ #include <stdint.h>
+ 
+-
+ #include "defs.h"
+ 
+ 
+ extern void __start_context(void);
+ 
+ 
++#define SAVEARG(i,val) \
++	do { \
++		*(i < 8 ? &ucp->uc_mcontext.gp_regs[3+i] : argp) = val; \
++		argp++; \
++	} while (0)
++
+ void
+ __makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
+ {
+ 	greg_t *sp, *argp;
+ 	va_list va;
+-	int i;
+-	unsigned int uc_link, stack_args;
++	unsigned int stack_args;
++
++	/* We pass uc_link as an argument, so in total we have argc+1 args */
++	stack_args = argc + 1;
+ 
+-	stack_args = argc > 8 ? argc - 8 : 0;
+-	uc_link = stack_args + 1;
++	/* We can pass 8 args before needing the stack.  If any arg is passed
++	 * on the stack, then stack space must be reserved for all args, even
++	 * though the first 8 don't need to be stored there */
++	if (stack_args <= 8) stack_args = 0;
+ 
+ 	sp = (greg_t *) ((uintptr_t) ucp->uc_stack.ss_sp + ucp->uc_stack.ss_size);
+-	sp -= (uc_link + 1);
++	sp -= stack_args + 4;
+ 	sp = (greg_t *) (((uintptr_t) sp & -16L));
+ 
+ 	ucp->uc_mcontext.gp_regs[REG_NIP]   = (uintptr_t) func;
+@@ -45,29 +53,13 @@ __makecontext(ucontext_t *ucp, void (*func)(void), int argc, ...)
+ 	ucp->uc_mcontext.gp_regs[REG_ENTRY] = (uintptr_t) func;
+ 	ucp->uc_mcontext.gp_regs[REG_R31]   = (uintptr_t) ucp->uc_link;
+ 
+-	sp[0] = (uintptr_t) &__start_context;
+-	sp[uc_link] = (uintptr_t) ucp->uc_link;
+-	argp = &sp[2];
++	sp[0] = 0;
++	argp = &sp[4];
+ 
+ 	va_start(va, argc);
+ 
+-	for (i = 0; i < argc; i++)
+-		switch (i)
+-		{
+-		case 0:
+-		case 1:
+-		case 2:
+-		case 3:
+-		case 4:
+-		case 5:
+-		case 6:
+-		case 7:
+-			ucp->uc_mcontext.gp_regs[i + 3] = va_arg (va, greg_t);
+-			break;
+-		default:
+-			*argp++ = va_arg (va, greg_t);
+-			break;
+-		}
++	for (int i = 0; i < argc; i++) SAVEARG(i, va_arg(va, greg_t));
++	SAVEARG(argc, (uintptr_t) ucp->uc_link);
+ 
+ 	va_end(va);
+ }
+-- 
+2.19.2
+