linux5.10: drop page poison patch in favor of fixing static keys
This commit is contained in:
q66
parent
1ea593eeda
commit
ad2b9bc075
3 changed files with 177 additions and 58 deletions
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@ -1,58 +0,0 @@
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This breaks page poisoning on some architectures. The commit is not
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very useful by itself, so revert it until a real fix is upstream.
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From 0cbb20875a8607653f02d799fd4b75a34d1b6636 Mon Sep 17 00:00:00 2001
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From: q66 <daniel@octaforge.org>
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Date: Mon, 25 Jan 2021 02:59:47 +0100
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Subject: [PATCH] Revert "mm/page_poison.c: replace bool variable with static
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key"
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This reverts commit 11c9c7edae06da789abfdeefe5123162a3f1c7dc.
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---
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mm/page_poison.c | 20 +++++---------------
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1 file changed, 5 insertions(+), 15 deletions(-)
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diff --git a/mm/page_poison.c b/mm/page_poison.c
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index ae0482c..34b9181 100644
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--- a/mm/page_poison.c
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+++ b/mm/page_poison.c
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@@ -8,23 +8,13 @@
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#include <linux/ratelimit.h>
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#include <linux/kasan.h>
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-static DEFINE_STATIC_KEY_FALSE_RO(want_page_poisoning);
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+static bool want_page_poisoning __read_mostly;
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static int __init early_page_poison_param(char *buf)
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{
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- int ret;
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- bool tmp;
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-
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- ret = strtobool(buf, &tmp);
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- if (ret)
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- return ret;
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-
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- if (tmp)
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- static_branch_enable(&want_page_poisoning);
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- else
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- static_branch_disable(&want_page_poisoning);
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-
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- return 0;
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+ if (!buf)
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+ return -EINVAL;
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+ return strtobool(buf, &want_page_poisoning);
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}
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early_param("page_poison", early_page_poison_param);
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@@ -41,7 +31,7 @@ bool page_poisoning_enabled(void)
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* Page poisoning is debug page alloc for some arches. If
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* either of those options are enabled, enable poisoning.
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*/
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- return (static_branch_unlikely(&want_page_poisoning) ||
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+ return (want_page_poisoning ||
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(!IS_ENABLED(CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC) &&
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debug_pagealloc_enabled()));
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}
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--
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2.30.0
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37
srcpkgs/linux5.10/patches/ppc-stack-traces-early-boot.patch
Normal file
37
srcpkgs/linux5.10/patches/ppc-stack-traces-early-boot.patch
Normal file
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@ -0,0 +1,37 @@
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From 0ecf6a9e47d825b7dddfebca738386b809e59a94 Mon Sep 17 00:00:00 2001
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From: Michael Ellerman <mpe@ellerman.id.au>
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Date: Wed, 3 Feb 2021 00:02:06 +1100
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Subject: powerpc/64: Make stack tracing work during very early boot
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If we try to stack trace very early during boot, either due to a
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WARN/BUG or manual dump_stack(), we will oops in
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valid_emergency_stack() when we try to dereference the paca_ptrs
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array.
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The fix is simple, we just return false if paca_ptrs isn't allocated
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yet. The stack pointer definitely isn't part of any emergency stack
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because we haven't allocated any yet.
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Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Link: https://lore.kernel.org/r/20210202130207.1303975-1-mpe@ellerman.id.au
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---
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arch/powerpc/kernel/process.c | 3 +++
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1 file changed, 3 insertions(+)
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diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
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index 8520ed5ae144d..e296440e9d16a 100644
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--- a/arch/powerpc/kernel/process.c
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+++ b/arch/powerpc/kernel/process.c
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@@ -2047,6 +2047,9 @@ static inline int valid_emergency_stack(unsigned long sp, struct task_struct *p,
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unsigned long stack_page;
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unsigned long cpu = task_cpu(p);
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+ if (!paca_ptrs)
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+ return 0;
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+
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stack_page = (unsigned long)paca_ptrs[cpu]->emergency_sp - THREAD_SIZE;
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if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
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return 1;
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--
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cgit 1.2.3-1.el7
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140
srcpkgs/linux5.10/patches/ppc64le-fix-static-keys.patch
Normal file
140
srcpkgs/linux5.10/patches/ppc64le-fix-static-keys.patch
Normal file
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@ -0,0 +1,140 @@
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From e7eb919057c3450cdd9d335e4a23a4da8da58db4 Mon Sep 17 00:00:00 2001
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From: Michael Ellerman <mpe@ellerman.id.au>
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Date: Wed, 3 Feb 2021 00:02:07 +1100
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Subject: [PATCH] powerpc/64s: Handle program checks in wrong endian during
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early boot
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There's a short window during boot where although the kernel is
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running little endian, any exceptions will cause the CPU to switch
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back to big endian. This situation persists until we call
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configure_exceptions(), which calls either the hypervisor or OPAL to
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configure the CPU so that exceptions will be taken in little
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endian (via HID0[HILE]).
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We don't intend to take exceptions during early boot, but one way we
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sometimes do is via a WARN/BUG etc. Those all boil down to a trap
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instruction, which will cause a program check exception.
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The first instruction of the program check handler is an mtsprg, which
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when executed in the wrong endian is an lhzu with a ~3GB displacement
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from r3. The content of r3 is random, so that becomes a load from some
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random location, and depending on the system (installed RAM etc.) can
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easily lead to a checkstop, or an infinitely recursive page fault.
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That prevents whatever the WARN/BUG was complaining about being
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printed to the console, and the user just sees a dead system.
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We can fix it by having a trampoline at the beginning of the program
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check handler that detects we are in the wrong endian, and flips us
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back to the correct endian.
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We can't flip MSR[LE] using mtmsr (alas), so we have to use rfid. That
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requires backing up SRR0/1 as well as a GPR. To do that we use
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SPRG0/2/3 (SPRG1 is already used for the paca). SPRG3 is user
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readable, but this trampoline is only active very early in boot, and
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SPRG3 will be reinitialised in vdso_getcpu_init() before userspace
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starts.
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With this trampoline in place we can survive a WARN early in boot and
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print a stack trace, which is eventually printed to the console once
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the console is up, eg:
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[83565.758545] kexec_core: Starting new kernel
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[ 0.000000] ------------[ cut here ]------------
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[ 0.000000] static_key_enable_cpuslocked(): static key '0xc000000000ea6160' used before call to jump_label_init()
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[ 0.000000] WARNING: CPU: 0 PID: 0 at kernel/jump_label.c:166 static_key_enable_cpuslocked+0xfc/0x120
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[ 0.000000] Modules linked in:
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[ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.10.0-gcc-8.2.0-dirty #618
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[ 0.000000] NIP: c0000000002fd46c LR: c0000000002fd468 CTR: c000000000170660
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[ 0.000000] REGS: c000000001227940 TRAP: 0700 Not tainted (5.10.0-gcc-8.2.0-dirty)
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[ 0.000000] MSR: 9000000002823003 <SF,HV,VEC,VSX,FP,ME,RI,LE> CR: 24882422 XER: 20040000
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[ 0.000000] CFAR: 0000000000000730 IRQMASK: 1
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[ 0.000000] GPR00: c0000000002fd468 c000000001227bd0 c000000001228300 0000000000000065
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[ 0.000000] GPR04: 0000000000000001 0000000000000065 c0000000010cf970 000000000000000d
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[ 0.000000] GPR08: 0000000000000000 0000000000000000 0000000000000000 c00000000122763f
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[ 0.000000] GPR12: 0000000000002000 c000000000f8a980 0000000000000000 0000000000000000
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[ 0.000000] GPR16: 0000000000000000 0000000000000000 c000000000f88c8e c000000000f88c9a
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[ 0.000000] GPR20: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
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[ 0.000000] GPR24: 0000000000000000 c000000000dea3a8 0000000000000000 c000000000f35114
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[ 0.000000] GPR28: 0000002800000000 c000000000f88c9a c000000000f88c8e c000000000ea6160
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[ 0.000000] NIP [c0000000002fd46c] static_key_enable_cpuslocked+0xfc/0x120
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[ 0.000000] LR [c0000000002fd468] static_key_enable_cpuslocked+0xf8/0x120
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[ 0.000000] Call Trace:
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[ 0.000000] [c000000001227bd0] [c0000000002fd468] static_key_enable_cpuslocked+0xf8/0x120 (unreliable)
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[ 0.000000] [c000000001227c40] [c0000000002fd4c0] static_key_enable+0x30/0x50
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[ 0.000000] [c000000001227c70] [c000000000f6629c] early_page_poison_param+0x58/0x9c
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[ 0.000000] [c000000001227cb0] [c000000000f351b8] do_early_param+0xa4/0x10c
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[ 0.000000] [c000000001227d30] [c00000000011e020] parse_args+0x270/0x5e0
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[ 0.000000] [c000000001227e20] [c000000000f35864] parse_early_options+0x48/0x5c
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[ 0.000000] [c000000001227e40] [c000000000f358d0] parse_early_param+0x58/0x84
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[ 0.000000] [c000000001227e70] [c000000000f3a368] early_init_devtree+0xc4/0x490
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[ 0.000000] [c000000001227f10] [c000000000f3bca0] early_setup+0xc8/0x1c8
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[ 0.000000] [c000000001227f90] [000000000000c320] 0xc320
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[ 0.000000] Instruction dump:
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[ 0.000000] 4bfffddd 7c2004ac 39200001 913f0000 4bffffb8 7c651b78 3c82ffac 3c62ffc0
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[ 0.000000] 38841b00 3863f310 4bdf03a5 60000000 <0fe00000> 4bffff38 60000000 60000000
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[ 0.000000] random: get_random_bytes called from print_oops_end_marker+0x40/0x80 with crng_init=0
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[ 0.000000] ---[ end trace 0000000000000000 ]---
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[ 0.000000] dt-cpu-ftrs: setup for ISA 3000
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Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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Link: https://lore.kernel.org/r/20210202130207.1303975-2-mpe@ellerman.id.au
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---
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arch/powerpc/kernel/exceptions-64s.S | 45 ++++++++++++++++++++++++++++
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1 file changed, 45 insertions(+)
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diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
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index b3793f982b2be..c51c436d5845f 100644
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--- a/arch/powerpc/kernel/exceptions-64s.S
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+++ b/arch/powerpc/kernel/exceptions-64s.S
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@@ -1630,6 +1630,51 @@ INT_DEFINE_BEGIN(program_check)
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INT_DEFINE_END(program_check)
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EXC_REAL_BEGIN(program_check, 0x700, 0x100)
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+
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+#ifdef CONFIG_CPU_LITTLE_ENDIAN
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+ /*
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+ * There's a short window during boot where although the kernel is
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+ * running little endian, any exceptions will cause the CPU to switch
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+ * back to big endian. For example a WARN() boils down to a trap
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+ * instruction, which will cause a program check, and we end up here but
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+ * with the CPU in big endian mode. The first instruction of the program
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+ * check handler (in GEN_INT_ENTRY below) is an mtsprg, which when
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+ * executed in the wrong endian is an lhzu with a ~3GB displacement from
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+ * r3. The content of r3 is random, so that is a load from some random
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+ * location, and depending on the system can easily lead to a checkstop,
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+ * or an infinitely recursive page fault.
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+ *
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+ * So to handle that case we have a trampoline here that can detect we
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+ * are in the wrong endian and flip us back to the correct endian. We
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+ * can't flip MSR[LE] using mtmsr, so we have to use rfid. That requires
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+ * backing up SRR0/1 as well as a GPR. To do that we use SPRG0/2/3, as
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+ * SPRG1 is already used for the paca. SPRG3 is user readable, but this
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+ * trampoline is only active very early in boot, and SPRG3 will be
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+ * reinitialised in vdso_getcpu_init() before userspace starts.
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+ */
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+BEGIN_FTR_SECTION
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+ tdi 0,0,0x48 // Trap never, or in reverse endian: b . + 8
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+ b 1f // Skip trampoline if endian is correct
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+ .long 0xa643707d // mtsprg 0, r11 Backup r11
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+ .long 0xa6027a7d // mfsrr0 r11
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+ .long 0xa643727d // mtsprg 2, r11 Backup SRR0 in SPRG2
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+ .long 0xa6027b7d // mfsrr1 r11
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+ .long 0xa643737d // mtsprg 3, r11 Backup SRR1 in SPRG3
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+ .long 0xa600607d // mfmsr r11
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+ .long 0x01006b69 // xori r11, r11, 1 Invert MSR[LE]
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+ .long 0xa6037b7d // mtsrr1 r11
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+ .long 0x34076039 // li r11, 0x734
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+ .long 0xa6037a7d // mtsrr0 r11
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+ .long 0x2400004c // rfid
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+ mfsprg r11, 3
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+ mtsrr1 r11 // Restore SRR1
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+ mfsprg r11, 2
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+ mtsrr0 r11 // Restore SRR0
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+ mfsprg r11, 0 // Restore r11
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+1:
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+END_FTR_SECTION(0, 1) // nop out after boot
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+#endif /* CONFIG_CPU_LITTLE_ENDIAN */
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+
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GEN_INT_ENTRY program_check, virt=0
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EXC_REAL_END(program_check, 0x700, 0x100)
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EXC_VIRT_BEGIN(program_check, 0x4700, 0x100)
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