PR/54702 CVS commit: [netbsd-9] src/sys/arch/aarch64/aarch64

["Martin Husemann" <martin%netbsd.org@localhost>]

The following reply was made to PR port-arm/54702; it has been noted by GNATS.

From: "Martin Husemann" <martin%netbsd.org@localhost>
To: gnats-bugs%gnats.NetBSD.org@localhost
Cc: 
Subject: PR/54702 CVS commit: [netbsd-9] src/sys/arch/aarch64/aarch64
Date: Fri, 1 Jan 2021 12:31:19 +0000

 Module Name:	src
 Committed By:	martin
 Date:		Fri Jan  1 12:31:19 UTC 2021
 
 Modified Files:
 	src/sys/arch/aarch64/aarch64 [netbsd-9]: trap.c
 
 Log Message:
 Pull up following revision(s) (requested by rin in ticket #1169):
 
 	sys/arch/aarch64/aarch64/trap.c: revision 1.21
 	sys/arch/aarch64/aarch64/trap.c: revision 1.26
 
 PR port-arm/54702
 Add support for earmv6hf binaries on COMPAT_NETBSD32 for aarch64:
 - Emulate ARMv6 instructions with cache operations register (c7), that
    are deprecated since ARMv7, and disabled on ARMv8 with LP64 kernel.
 
 Many thanks to ryo@ for helping me to add support of Thumb-mode,
 as well as providing exhaustive test cases:
    https://github.com/ryo/mcr_test/
 
 We've confirmed:
 - Emulation works in Thumb-mode.
 - T32 16-bit length illegal instruction results in SIGILL, even if
    it is located nearby a boundary b/w mapped and unmapped pages.
 - T32 32-bit instruction results in SIGSEGV if it is located across
    a boundary b/w mapped and unmapped pages.
 
 When emulating obsoleted arm32 instructions, use ufetch(9) rather than
 dereference tf_pc directly to retrieve an instruction.
 Even if tf_pc is valid when processor decodes the instruction, someone
 can unmap its page before tf_pc is read in the exception handler.
 Now, SIGSEGV is delivered correctly to the process in this case, rather
 than kernel panic.
 
 Pointed out by maxv.
 
 Discussed with ryo and skrll.
 
 
 To generate a diff of this commit:
 cvs rdiff -u -r1.17.4.2 -r1.17.4.3 src/sys/arch/aarch64/aarch64/trap.c
 
 Please note that diffs are not public domain; they are subject to the
 copyright notices on the relevant files.