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signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die

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In the fpsp040 code when copyin or copyout fails call
force_sigsegv(SIGSEGV) instead of do_exit(SIGSEGV).

This solves a couple of problems.  Because do_exit embeds the ptrace
stop PTRACE_EVENT_EXIT a complete stack frame needs to be present for
that to work correctly.  There is always the information needed for a
ptrace stop where get_signal is called.  So exiting with a signal
solves the ptrace issue.

Further exiting with a signal ensures that all of the threads in a
process are killed not just the thread that malfunctioned.  Which
avoids confusing userspace.

To make force_sigsegv(SIGSEGV) work in fpsp040_die modify the code to
save all of the registers and jump to ret_from_exception (which
ultimately calls get_signal) after fpsp040_die returns.

v2: Updated the branches to use gas's pseudo ops that automatically
    calculate the best branch instruction to use for the purpose.

v1: https://lkml.kernel.org/r/87a6m8kgtx.fsf_-_@disp2133
Link: https://lkml.kernel.org/r/87tukghjfs.fsf_-_@disp2133
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
This commit is contained in:
Eric W. Biederman 2021-07-26 14:23:11 -05:00
parent b48c7236b1
commit a3616a3c02
2 changed files with 3 additions and 2 deletions
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3
arch/m68k/fpsp040/skeleton.S
View file

@ -502,7 +502,8 @@ in_ea:
.section .fixup,#alloc,#execinstr
.even
1:
jbra fpsp040_die
jbsr fpsp040_die
jbra .Lnotkern
.section __ex_table,#alloc
.align 4

2
arch/m68k/kernel/traps.c
View file

@ -1150,7 +1150,7 @@ asmlinkage void set_esp0(unsigned long ssp)
*/
asmlinkage void fpsp040_die(void)
{
do_exit(SIGSEGV);
force_sigsegv(SIGSEGV);
}
#ifdef CONFIG_M68KFPU_EMU