[PATCH] uml: Use klibc setjmp/longjmp

This patch adds an implementation of setjmp and longjmp to UML, allowing
access to the inside of a jmpbuf without needing the access macros formerly
provided by libc.

The implementation is stolen from klibc.  I copy the relevant files into
arch/um.  I have another patch which avoids the copying, but requires klibc be
in the tree.

setjmp and longjmp users required some tweaking.  Includes of <setjmp.h> were
removed and includes of the UML longjmp.h were added where necessary.  There
are also replacements of siglongjmp with UML_LONGJMP which I somehow missed
earlier.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 54 insertions, 0 deletions

diff --git a/arch/um/sys-x86_64/setjmp.S b/arch/um/sys-x86_64/setjmp.S
new file mode 100644
index 000000000000..45f547b4043e
--- /dev/null
+++ b/arch/um/sys-x86_64/setjmp.S
@@ -0,0 +1,54 @@
+#
+# arch/x86_64/setjmp.S
+#
+# setjmp/longjmp for the x86-64 architecture
+#
+
+#
+# The jmp_buf is assumed to contain the following, in order:
+#	%rbx
+#	%rsp (post-return)
+#	%rbp
+#	%r12
+#	%r13
+#	%r14
+#	%r15
+#	<return address>
+#
+
+	.text
+	.align 4
+	.globl setjmp
+	.type setjmp, @function
+setjmp:
+	pop  %rsi			# Return address, and adjust the stack
+	xorl %eax,%eax			# Return value
+	movq %rbx,(%rdi)
+	movq %rsp,8(%rdi)		# Post-return %rsp!
+	push %rsi			# Make the call/return stack happy
+	movq %rbp,16(%rdi)
+	movq %r12,24(%rdi)
+	movq %r13,32(%rdi)
+	movq %r14,40(%rdi)
+	movq %r15,48(%rdi)
+	movq %rsi,56(%rdi)		# Return address
+	ret
+
+	.size setjmp,.-setjmp
+
+	.text
+	.align 4
+	.globl longjmp
+	.type longjmp, @function
+longjmp:
+	movl %esi,%eax			# Return value (int)
+	movq (%rdi),%rbx
+	movq 8(%rdi),%rsp
+	movq 16(%rdi),%rbp
+	movq 24(%rdi),%r12
+	movq 32(%rdi),%r13
+	movq 40(%rdi),%r14
+	movq 48(%rdi),%r15
+	jmp *56(%rdi)
+
+	.size longjmp,.-longjmp