The following commit has been merged into the x86/asm branch of tip: Commit-ID: 559ceeed62a5121783a8955c63aeb18aaa0ef224 Gitweb: https://git.kernel.org/tip/559ceeed62a5121783a8955c63aeb18aaa0ef224 Author: Jiri Slaby <jslaby@xxxxxxx> AuthorDate: Fri, 06 Sep 2019 09:55:49 +02:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Fri, 06 Sep 2019 10:34:15 +02:00 x86/asm/suspend: Get rid of bogus_64_magic bogus_64_magic is only a dead-end loop. There is no need for an out-of-order function (and unannotated local label), so just handle it in-place and also store 0xbad-m-a-g-i-c to %rcx beforehand, in case someone is inspecting registers. Here a qemu+gdb example: Remote debugging using localhost:1235 wakeup_long64 () at arch/x86/kernel/acpi/wakeup_64.S:26 26 jmp 1b (gdb) info registers rax 0x123456789abcdef0 1311768467463790320 rbx 0x0 0 rcx 0xbad6d61676963 3286910041024867 ^^^^^^^^^^^^^^^ [ bp: Add the gdb example. ] Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> Signed-off-by: Borislav Petkov <bp@xxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Cc: Len Brown <lenb@xxxxxxxxxx> Cc: linux-pm@xxxxxxxxxxxxxxx Cc: Pavel Machek <pavel@xxxxxx> Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: x86-ml <x86@xxxxxxxxxx> Link: https://lkml.kernel.org/r/20190906075550.23435-1-jslaby@xxxxxxx --- arch/x86/kernel/acpi/wakeup_64.S | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/acpi/wakeup_64.S b/arch/x86/kernel/acpi/wakeup_64.S index b0715c3..7f9ade1 100644 --- a/arch/x86/kernel/acpi/wakeup_64.S +++ b/arch/x86/kernel/acpi/wakeup_64.S @@ -18,8 +18,13 @@ ENTRY(wakeup_long64) movq saved_magic, %rax movq $0x123456789abcdef0, %rdx cmpq %rdx, %rax - jne bogus_64_magic + je 2f + /* stop here on a saved_magic mismatch */ + movq $0xbad6d61676963, %rcx +1: + jmp 1b +2: movw $__KERNEL_DS, %ax movw %ax, %ss movw %ax, %ds @@ -37,9 +42,6 @@ ENTRY(wakeup_long64) jmp *%rax ENDPROC(wakeup_long64) -bogus_64_magic: - jmp bogus_64_magic - ENTRY(do_suspend_lowlevel) FRAME_BEGIN subq $8, %rsp
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