lkml.org 
[lkml]   [2022]   [Jul]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [x86,static_call] ee88d363d1: WARNING:at_arch/x86/kernel/alternative.c:#apply_returns
On Wed, Jul 13, 2022 at 04:02:15PM +0800, kernel test robot wrote:

> [ 22.065014][ T0] ------------[ cut here ]------------
> [ 22.066738][ T0] WARNING: CPU: 0 PID: 0 at arch/x86/kernel/alternative.c:557 apply_returns (arch/x86/kernel/alternative.c:557 (discriminator 1))
> [ 22.069534][ T0] Modules linked in:
> [ 22.070738][ T0] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc4-00008-gee88d363d156 #1
> [ 22.072739][ T0] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-4 04/01/2014
> [ 22.074741][ T0] RIP: 0010:apply_returns (arch/x86/kernel/alternative.c:557 (discriminator 1))
> [ 22.076739][ T0] Code: ff ff 74 cb 48 83 c5 04 49 39 ee 0f 87 81 fe ff ff e9 22 ff ff ff 0f 0b 48 83 c5 04 49 39 ee 0f 87 6d fe ff ff e9 0e ff ff ff <0f> 0b 48 83 c5 04 49 39 ee 0f 87 59 fe ff ff e9 fa fe ff ff 48 89
> All code
> ========
> 0: ff (bad)
> 1: ff 74 cb 48 pushq 0x48(%rbx,%rcx,8)
> 5: 83 c5 04 add $0x4,%ebp
> 8: 49 39 ee cmp %rbp,%r14
> b: 0f 87 81 fe ff ff ja 0xfffffffffffffe92
> 11: e9 22 ff ff ff jmpq 0xffffffffffffff38
> 16: 0f 0b ud2
> 18: 48 83 c5 04 add $0x4,%rbp
> 1c: 49 39 ee cmp %rbp,%r14
> 1f: 0f 87 6d fe ff ff ja 0xfffffffffffffe92
> 25: e9 0e ff ff ff jmpq 0xffffffffffffff38
> 2a:* 0f 0b ud2 <-- trapping instruction
> 2c: 48 83 c5 04 add $0x4,%rbp
> 30: 49 39 ee cmp %rbp,%r14
> 33: 0f 87 59 fe ff ff ja 0xfffffffffffffe92
> 39: e9 fa fe ff ff jmpq 0xffffffffffffff38
> 3e: 48 rex.W
> 3f: 89 .byte 0x89
>
> Code starting with the faulting instruction
> ===========================================
> 0: 0f 0b ud2
> 2: 48 83 c5 04 add $0x4,%rbp
> 6: 49 39 ee cmp %rbp,%r14
> 9: 0f 87 59 fe ff ff ja 0xfffffffffffffe68
> f: e9 fa fe ff ff jmpq 0xffffffffffffff0e
> 14: 48 rex.W
> 15: 89 .byte 0x89
> [ 22.078738][ T0] RSP: 0000:ffffffffa2807dc0 EFLAGS: 00010202
> [ 22.080737][ T0] RAX: 0000000000000000 RBX: ffffffffa1b8fe05 RCX: 0000000000000000
> [ 22.082546][ T0] RDX: 000000000000000f RSI: ffffffffa184a3e0 RDI: ffffffffa1b8fe05
> [ 22.083738][ T0] RBP: ffffffffa42851e8 R08: 0000000000000001 R09: ffffffffa1b8fe05
> [ 22.086491][ T0] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffa1b8fe00
> [ 22.087738][ T0] R13: dffffc0000000000 R14: ffffffffa4299890 R15: 1ffffffff4500fbb
> [ 22.089739][ T0] FS: 0000000000000000(0000) GS:ffff888396600000(0000) knlGS:0000000000000000
> [ 22.091743][ T0] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 22.093738][ T0] CR2: ffff88843ffff000 CR3: 00000003a562a000 CR4: 00000000000006f0
> [ 22.095753][ T0] Call Trace:
> [ 22.097742][ T0] <TASK>
> [ 22.098765][ T0] ? rwlock_bug+0xc0/0xc0
> [ 22.100230][ T0] ? apply_retpolines (arch/x86/kernel/alternative.c:538)
> [ 22.101791][ T0] ? int3_exception_notify (arch/x86/kernel/alternative.c:849)
> [ 22.103261][ T0] ? check_bugs (arch/x86/kernel/cpu/bugs.c:149)
> [ 22.104751][ T0] alternative_instructions (arch/x86/kernel/alternative.c:932)
> [ 22.106766][ T0] check_bugs (arch/x86/kernel/cpu/bugs.c:159)
> [ 22.108244][ T0] start_kernel (init/main.c:1132)
> [ 22.109747][ T0] secondary_startup_64_no_verify (arch/x86/kernel/head_64.S:358)
> [ 22.111300][ T0] </TASK>
> [ 22.112742][ T0] irq event stamp: 87769
> [ 22.113741][ T0] hardirqs last enabled at (87781): __up_console_sem (arch/x86/include/asm/irqflags.h:45 (discriminator 1) arch/x86/include/asm/irqflags.h:80 (discriminator 1) arch/x86/include/asm/irqflags.h:138 (discriminator 1) kernel/printk/printk.c:264 (discriminator 1))
> [ 22.115740][ T0] hardirqs last disabled at (87794): __up_console_sem (kernel/printk/printk.c:262 (discriminator 1))
> [ 22.117739][ T0] softirqs last enabled at (2774): cgroup_idr_alloc+0x5b/0x1c0
> [ 22.119739][ T0] softirqs last disabled at (2772): cgroup_idr_alloc+0x2e/0x1c0
> [ 22.121741][ T0] ---[ end trace 0000000000000000 ]---


diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index d6858533e6e5..ff309e829192 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -555,8 +555,10 @@ void __init_or_module noinline apply_returns(s32 *start, s32 *end)
dest = addr + insn.length + insn.immediate.value;

if (__static_call_fixup(addr, op, dest) ||
- WARN_ON_ONCE(dest != &__x86_return_thunk))
+ WARN_ON_ONCE(dest != &__x86_return_thunk)) {
+ printk("XXX: %pS %pS : %*ph", addr, dest, 5, addr);
continue;
+ }

DPRINTK("return thunk at: %pS (%px) len: %d to: %pS",
addr, addr, insn.length,
Gets me:

[ 2.559091][ T0] ---[ end trace 0000000000000000 ]---
[ 2.561092][ T0] XXX: lkdtm_rodata_do_nothing+0x0/0x1240 lkdtm_rodata_do_nothing+0x5/0x1240 : e9 00 00 00 00
which is a result of:

drivers/misc/lkdtm/Makefile:OBJCOPYFLAGS_rodata_objcopy.o := \
drivers/misc/lkdtm/Makefile: --rename-section .noinstr.text=.rodata,alloc,readonly,load,contents

which makes that:

0000000000000000 <lkdtm_rodata_do_nothing>:
0: e9 00 00 00 00 jmp 5 <lkdtm_rodata_do_nothing+0x5> 1: R_X86_64_PLT32 __x86_return_thunk-0x4
remains unresolved.

Kees, what's up with that thing, this is 'weird' at best.

\
 
 \ /
  Last update: 2022-07-13 14:29    [W:0.045 / U:0.404 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site