Hi Michael,
On Wed, Jun 23, 2021 at 2:21 AM Michael Schmitz <schmitzmic@xxxxxxxxx> wrote:
Add 'status' field to thread_info struct to hold syscall trace
status info.
Set flag bit in thread_info->status at syscall trace entry, clear
flag bit on trace exit.
Set another flag bit on entering syscall where the full stack
frame has been saved. These flags can be checked whenever a
syscall calls ptrace_stop().
Check flag bits in get_reg()/put_reg() and prevent access to
registers that are saved on the switch stack, in case the
syscall did not actually save these registers on the switch
stack.
Tested on ARAnyM only - boots and survives running strace on a
binary, nothing fancy.
CC: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
CC: Andreas Schwab <schwab@xxxxxxxxxxxxxx>
Signed-off-by: Michael Schmitz <schmitzmic@xxxxxxxxx>
Thanks for your patch!
--- a/arch/m68k/kernel/entry.S
+++ b/arch/m68k/kernel/entry.S
@@ -51,75 +51,115 @@
.text
ENTRY(__sys_fork)
+ movel %curptr@(TASK_STACK),%a1
+ orb #TIS_SWITCH_STACK, %a1@(TINFO_STATUS+3)
This doesn't work on Coldfire:
arch/m68k/kernel/entry.S:55: Error: invalid instruction for this
architecture; needs 68000 or higher (68000 [68ec000, 68hc000, 68hc001,
68008, 68302, 68306, 68307, 68322, 68356], 68010, 68020 [68k,
68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060], cpu32
[68330, 68331, 68332,
68333, 68334, 68336, 68340, 68341, 68349, 68360], fidoa [fido]) --
statement `orb #(1<<1),%a1@(16+3)' ignored
SAVE_SWITCH_STACK
jbsr sys_fork
lea %sp@(24),%sp
+ movel %curptr@(TASK_STACK),%a1
+ andb #TIS_NO_SWITCH_STACK, %a1@(TINFO_STATUS+3)
arch/m68k/kernel/entry.S:60: Error: invalid instruction for this
architecture; needs 68000 or higher (68000 [68ec000, 68hc000, 68hc001,
68008, 68302, 68306, 68307, 68322, 68356], 68010, 68020 [68k,
68ec020], 68030 [68ec030], 68040 [68ec040], 68060 [68ec060], cpu32
[68330, 68331, 68332, 68333, 68334, 68336, 68340, 68341, 68349,
68360], fidoa [fido]) -- statement `andb #(~((1<<1))),%a1@(16+3)'
ignored
rts
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
