diff options
| author | Christophe Leroy <christophe.leroy@c-s.fr> | 2020-01-31 11:34:54 +0000 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2020-02-19 22:46:08 +1100 |
| commit | 9e27086292aa880921a0f2b8501e5189d5efcf03 (patch) | |
| tree | 79b9c6c21074e5da094dce9cf912ad3b7bd313b3 /arch/powerpc/kernel/entry_32.S | |
| parent | 030e347430957f6f7f29db9099368f8b86c0bf76 (diff) | |
powerpc/32: Warn and return ENOSYS on syscalls from kernel
Since commit b86fb88855ea ("powerpc/32: implement fast entry for
syscalls on non BOOKE") and commit 1a4b739bbb4f ("powerpc/32:
implement fast entry for syscalls on BOOKE"), syscalls from
kernel are unexpected and can have catastrophic consequences
as it will destroy the kernel stack.
Test MSR_PR on syscall entry. In case syscall is from kernel,
emit a warning and return ENOSYS error.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8ee3bdbbdfdfc64ca7001e90c43b2aee6f333578.1580470482.git.christophe.leroy@c-s.fr
Diffstat (limited to 'arch/powerpc/kernel/entry_32.S')
| -rw-r--r-- | arch/powerpc/kernel/entry_32.S | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index 0713daa651d9..ad000cbb5252 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -575,6 +575,33 @@ syscall_exit_work: bl do_syscall_trace_leave b ret_from_except_full + /* + * System call was called from kernel. We get here with SRR1 in r9. + * Mark the exception as recoverable once we have retrieved SRR0, + * trap a warning and return ENOSYS with CR[SO] set. + */ + .globl ret_from_kernel_syscall +ret_from_kernel_syscall: + mfspr r9, SPRN_SRR0 + mfspr r10, SPRN_SRR1 +#if !defined(CONFIG_4xx) && !defined(CONFIG_BOOKE) + LOAD_REG_IMMEDIATE(r11, MSR_KERNEL & ~(MSR_IR|MSR_DR)) + mtmsr r11 +#endif + +0: trap + EMIT_BUG_ENTRY 0b,__FILE__,__LINE__, BUGFLAG_WARNING + + li r3, ENOSYS + crset so +#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PERF_EVENTS) + mtspr SPRN_NRI, r0 +#endif + mtspr SPRN_SRR0, r9 + mtspr SPRN_SRR1, r10 + SYNC + RFI + /* * The fork/clone functions need to copy the full register set into * the child process. Therefore we need to save all the nonvolatile |