Belatedly, ARM has taken a slice of the reserved opcode space and
assigned it as a properly defined illegal instruction, udf #imm16.
(Armv8 Architecture Reference Manual, edition F.c, section C6.2.335).
Clang already knows about it.
We really should use this instead of picking something ad-hoc out
of the opcode space.
I have verified that this builds on arm64, produces a SIGILL in
userland, and drops me into ddb in the kernel.
armv7 has an equivalent instruction. kettenis@ confirms it builds
and SIGILLs there.
OK?
Index: lib/csu/aarch64/md_init.h
===================================================================
RCS file: /cvs/src/lib/csu/aarch64/md_init.h,v
retrieving revision 1.9
diff -u -p -r1.9 md_init.h
--- lib/csu/aarch64/md_init.h 15 Oct 2020 16:30:21 -0000 1.9
+++ lib/csu/aarch64/md_init.h 19 Oct 2020 11:57:02 -0000
@@ -115,5 +115,5 @@
" svc #0 \n" \
" dsb nsh \n" \
" isb \n" \
- " .word 0xa000f7f0 /* illegal */ \n" \
+ " udf #0 \n" \
".previous");
Index: lib/csu/arm/md_init.h
===================================================================
RCS file: /cvs/src/lib/csu/arm/md_init.h,v
retrieving revision 1.16
diff -u -p -r1.16 md_init.h
--- lib/csu/arm/md_init.h 15 Oct 2020 16:30:23 -0000 1.16
+++ lib/csu/arm/md_init.h 19 Oct 2020 13:23:00 -0000
@@ -159,5 +159,5 @@
" swi #0 \n" \
" dsb nsh \n" \
" isb \n" \
- " .word 0xa000f7f0 /* illegal */ \n" \
+ " udf #0 \n" \
".previous");
Index: lib/libc/arch/aarch64/sys/tfork_thread.S
===================================================================
RCS file: /cvs/src/lib/libc/arch/aarch64/sys/tfork_thread.S,v
retrieving revision 1.5
diff -u -p -r1.5 tfork_thread.S
--- lib/libc/arch/aarch64/sys/tfork_thread.S 18 Oct 2020 14:28:16 -0000
1.5
+++ lib/libc/arch/aarch64/sys/tfork_thread.S 19 Oct 2020 11:59:32 -0000
@@ -43,6 +43,6 @@ ENTRY(__tfork_thread)
mov x0, x3
blr x2
SYSTRAP(__threxit)
- .word 0xa000f7f0 /* illegal on all cpus? */
+ udf #0
.cfi_endproc
END(__tfork_thread)
Index: lib/libc/arch/arm/sys/tfork_thread.S
===================================================================
RCS file: /cvs/src/lib/libc/arch/arm/sys/tfork_thread.S,v
retrieving revision 1.5
diff -u -p -r1.5 tfork_thread.S
--- lib/libc/arch/arm/sys/tfork_thread.S 18 Oct 2020 14:28:17 -0000
1.5
+++ lib/libc/arch/arm/sys/tfork_thread.S 19 Oct 2020 13:23:35 -0000
@@ -37,5 +37,5 @@ ENTRY(__tfork_thread)
mov pc, r2
nop
SYSTRAP(__threxit)
- .word 0xa000f7f0 /* illegal on all cpus? */
+ udf #0
END(__tfork_thread)
Index: sys/arch/arm/arm/sigcode.S
===================================================================
RCS file: /cvs/src/sys/arch/arm/arm/sigcode.S,v
retrieving revision 1.9
diff -u -p -r1.9 sigcode.S
--- sys/arch/arm/arm/sigcode.S 13 Mar 2020 08:46:50 -0000 1.9
+++ sys/arch/arm/arm/sigcode.S 19 Oct 2020 13:23:55 -0000
@@ -72,7 +72,7 @@ _C_LABEL(esigcode):
.globl sigfill
sigfill:
- .word 0xa000f7f0 /* illegal on all cpus? */
+ udf #0
esigfill:
.data
Index: sys/arch/arm64/arm64/locore.S
===================================================================
RCS file: /cvs/src/sys/arch/arm64/arm64/locore.S,v
retrieving revision 1.31
diff -u -p -r1.31 locore.S
--- sys/arch/arm64/arm64/locore.S 13 Mar 2020 00:14:38 -0000 1.31
+++ sys/arch/arm64/arm64/locore.S 19 Oct 2020 12:02:23 -0000
@@ -366,7 +366,7 @@ _C_LABEL(esigcode):
.globl sigfill
sigfill:
- .word 0xa000f7f0 /* FIXME: illegal on all cpus? */
+ udf #0
esigfill:
.data
--
Christian "naddy" Weisgerber [email protected]
