Revision 595d153dd1022392083ac93a1550382cbee127e0 authored by Michael Ellerman on 26 May 2020, 06:18:08 UTC, committed by Michael Ellerman on 26 May 2020, 07:32:37 UTC
Commit 702f09805222 ("powerpc/64s/exception: Remove lite interrupt
return") changed the interrupt return path to not restore non-volatile
registers by default, and explicitly restore them in paths where it is
required.
But it missed that the facility unavailable exception can sometimes
modify user registers, ie. when it does emulation of move from DSCR.
This is seen as a failure of the dscr_sysfs_thread_test:
test: dscr_sysfs_thread_test
[cpu 0] User DSCR should be 1 but is 0
failure: dscr_sysfs_thread_test
So restore non-volatile GPRs after facility unavailable exceptions.
Currently the hypervisor facility unavailable exception is also wired
up to call facility_unavailable_exception().
In practice we should never take a hypervisor facility unavailable
exception for the DSCR. On older bare metal systems we set HFSCR_DSCR
unconditionally in __init_HFSCR, or on newer systems it should be
enabled via the "data-stream-control-register" device tree CPU
feature.
Even if it's not, since commit f3c99f97a3cd ("KVM: PPC: Book3S HV:
Don't access HFSCR, LPIDR or LPCR when running nested"), the KVM code
has unconditionally set HFSCR_DSCR when running guests.
So we should only get a hypervisor facility unavailable for the DSCR
if skiboot has disabled the "data-stream-control-register" feature,
and we are somehow in guest context but not via KVM.
Given all that, it should be unnecessary to add a restore of
non-volatile GPRs after the hypervisor facility exception, because we
never expect to hit that path. But equally we may as well add the
restore, because we never expect to hit that path, and if we ever did,
at least we would correctly restore the registers to their post
emulation state.
In future we can split the non-HV and HV facility unavailable handling
so that there is no emulation in the HV handler, and then remove the
restore for the HV case.
Fixes: 702f09805222 ("powerpc/64s/exception: Remove lite interrupt return")
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200526061808.2472279-1-mpe@ellerman.id.au
1 parent 8659a0e
checkstack.pl
#!/usr/bin/env perl
# SPDX-License-Identifier: GPL-2.0
# Check the stack usage of functions
#
# Copyright Joern Engel <joern@lazybastard.org>
# Inspired by Linus Torvalds
# Original idea maybe from Keith Owens
# s390 port and big speedup by Arnd Bergmann <arnd@bergmann-dalldorf.de>
# Mips port by Juan Quintela <quintela@mandrakesoft.com>
# IA64 port via Andreas Dilger
# Arm port by Holger Schurig
# sh64 port by Paul Mundt
# Random bits by Matt Mackall <mpm@selenic.com>
# M68k port by Geert Uytterhoeven and Andreas Schwab
# AArch64, PARISC ports by Kyle McMartin
# sparc port by Martin Habets <errandir_news@mph.eclipse.co.uk>
# ppc64le port by Breno Leitao <leitao@debian.org>
#
# Usage:
# objdump -d vmlinux | scripts/checkstack.pl [arch]
#
# TODO : Port to all architectures (one regex per arch)
use strict;
# check for arch
#
# $re is used for two matches:
# $& (whole re) matches the complete objdump line with the stack growth
# $1 (first bracket) matches the size of the stack growth
#
# $dre is similar, but for dynamic stack redutions:
# $& (whole re) matches the complete objdump line with the stack growth
# $1 (first bracket) matches the dynamic amount of the stack growth
#
# use anything else and feel the pain ;)
my (@stack, $re, $dre, $x, $xs, $funcre);
{
my $arch = shift;
if ($arch eq "") {
$arch = `uname -m`;
chomp($arch);
}
$x = "[0-9a-f]"; # hex character
$xs = "[0-9a-f ]"; # hex character or space
$funcre = qr/^$x* <(.*)>:$/;
if ($arch =~ '^(aarch|arm)64$') {
#ffffffc0006325cc: a9bb7bfd stp x29, x30, [sp, #-80]!
#a110: d11643ff sub sp, sp, #0x590
$re = qr/^.*stp.*sp, \#-([0-9]{1,8})\]\!/o;
$dre = qr/^.*sub.*sp, sp, #(0x$x{1,8})/o;
} elsif ($arch eq 'arm') {
#c0008ffc: e24dd064 sub sp, sp, #100 ; 0x64
$re = qr/.*sub.*sp, sp, #(([0-9]{2}|[3-9])[0-9]{2})/o;
} elsif ($arch =~ /^x86(_64)?$/ || $arch =~ /^i[3456]86$/) {
#c0105234: 81 ec ac 05 00 00 sub $0x5ac,%esp
# or
# 2f60: 48 81 ec e8 05 00 00 sub $0x5e8,%rsp
$re = qr/^.*[as][du][db] \$(0x$x{1,8}),\%(e|r)sp$/o;
$dre = qr/^.*[as][du][db] (%.*),\%(e|r)sp$/o;
} elsif ($arch eq 'ia64') {
#e0000000044011fc: 01 0f fc 8c adds r12=-384,r12
$re = qr/.*adds.*r12=-(([0-9]{2}|[3-9])[0-9]{2}),r12/o;
} elsif ($arch eq 'm68k') {
# 2b6c: 4e56 fb70 linkw %fp,#-1168
# 1df770: defc ffe4 addaw #-28,%sp
$re = qr/.*(?:linkw %fp,|addaw )#-([0-9]{1,4})(?:,%sp)?$/o;
} elsif ($arch eq 'mips64') {
#8800402c: 67bdfff0 daddiu sp,sp,-16
$re = qr/.*daddiu.*sp,sp,-(([0-9]{2}|[3-9])[0-9]{2})/o;
} elsif ($arch eq 'mips') {
#88003254: 27bdffe0 addiu sp,sp,-32
$re = qr/.*addiu.*sp,sp,-(([0-9]{2}|[3-9])[0-9]{2})/o;
} elsif ($arch eq 'nios2') {
#25a8: defffb04 addi sp,sp,-20
$re = qr/.*addi.*sp,sp,-(([0-9]{2}|[3-9])[0-9]{2})/o;
} elsif ($arch eq 'openrisc') {
# c000043c: 9c 21 fe f0 l.addi r1,r1,-272
$re = qr/.*l\.addi.*r1,r1,-(([0-9]{2}|[3-9])[0-9]{2})/o;
} elsif ($arch eq 'parisc' || $arch eq 'parisc64') {
$re = qr/.*ldo ($x{1,8})\(sp\),sp/o;
} elsif ($arch eq 'powerpc' || $arch =~ /^ppc(64)?(le)?$/ ) {
# powerpc : 94 21 ff 30 stwu r1,-208(r1)
# ppc64(le) : 81 ff 21 f8 stdu r1,-128(r1)
$re = qr/.*st[dw]u.*r1,-($x{1,8})\(r1\)/o;
} elsif ($arch =~ /^s390x?$/) {
# 11160: a7 fb ff 60 aghi %r15,-160
# or
# 100092: e3 f0 ff c8 ff 71 lay %r15,-56(%r15)
$re = qr/.*(?:lay|ag?hi).*\%r15,-(([0-9]{2}|[3-9])[0-9]{2})
(?:\(\%r15\))?$/ox;
} elsif ($arch =~ /^sh64$/) {
#XXX: we only check for the immediate case presently,
# though we will want to check for the movi/sub
# pair for larger users. -- PFM.
#a00048e0: d4fc40f0 addi.l r15,-240,r15
$re = qr/.*addi\.l.*r15,-(([0-9]{2}|[3-9])[0-9]{2}),r15/o;
} elsif ($arch eq 'sparc' || $arch eq 'sparc64') {
# f0019d10: 9d e3 bf 90 save %sp, -112, %sp
$re = qr/.*save.*%sp, -(([0-9]{2}|[3-9])[0-9]{2}), %sp/o;
} else {
print("wrong or unknown architecture \"$arch\"\n");
exit
}
}
#
# main()
#
my ($func, $file, $lastslash);
while (my $line = <STDIN>) {
if ($line =~ m/$funcre/) {
$func = $1;
}
elsif ($line =~ m/(.*):\s*file format/) {
$file = $1;
$file =~ s/\.ko//;
$lastslash = rindex($file, "/");
if ($lastslash != -1) {
$file = substr($file, $lastslash + 1);
}
}
elsif ($line =~ m/$re/) {
my $size = $1;
$size = hex($size) if ($size =~ /^0x/);
if ($size > 0xf0000000) {
$size = - $size;
$size += 0x80000000;
$size += 0x80000000;
}
next if ($size > 0x10000000);
next if $line !~ m/^($xs*)/;
my $addr = $1;
$addr =~ s/ /0/g;
$addr = "0x$addr";
my $intro = "$addr $func [$file]:";
my $padlen = 56 - length($intro);
while ($padlen > 0) {
$intro .= ' ';
$padlen -= 8;
}
next if ($size < 100);
push @stack, "$intro$size\n";
}
elsif (defined $dre && $line =~ m/$dre/) {
my $size = "Dynamic ($1)";
next if $line !~ m/^($xs*)/;
my $addr = $1;
$addr =~ s/ /0/g;
$addr = "0x$addr";
my $intro = "$addr $func [$file]:";
my $padlen = 56 - length($intro);
while ($padlen > 0) {
$intro .= ' ';
$padlen -= 8;
}
push @stack, "$intro$size\n";
}
}
# Sort output by size (last field)
print sort { ($b =~ /:\t*(\d+)$/)[0] <=> ($a =~ /:\t*(\d+)$/)[0] } @stack;
Computing file changes ...
