Messages in this thread |  | | Date | Wed, 18 Feb 2015 08:50:56 +0200 | From | Purcareata Bogdan <> | Subject | Re: [PATCH v3 1/3] powerpc: Don't force ENOSYS as error on syscall fail |
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On 18.02.2015 05:01, Mike Strosaker wrote: > This patch failed to build using pseries_le_defconfig. With the change > noted below in entry_64.S, the build succeeded and seccomp mode 2 worked > correctly. > > Best, > Mike Strosaker > > On 02/13/2015 02:22 AM, Bogdan Purcareata wrote: >> In certain scenarios - e.g. seccomp filtering with ERRNO as default action - >> the system call fails for other reasons than the syscall not being available. >> The seccomp filter can be configured to store a user-defined error code on >> return from a blacklisted syscall. Don't always set ENOSYS on >> do_syscall_trace_enter failure. >> >> Delegate setting ENOSYS in case of failure, where appropriate, to >> do_syscall_trace_enter. >> >> v3: >> - keep setting ENOSYS in the syscall entry assembly for scenarios without >> syscall tracing >> >> v2: >> - move setting ENOSYS as errno from the syscall entry assembly to >> do_syscall_trace_enter, only in the specific case >> >> Signed-off-by: Bogdan Purcareata <bogdan.purcareata@freescale.com> >> --- >> arch/powerpc/kernel/entry_32.S | 7 ++++++- >> arch/powerpc/kernel/entry_64.S | 5 +++-- >> arch/powerpc/kernel/ptrace.c | 4 +++- >> 3 files changed, 12 insertions(+), 4 deletions(-) >> >> diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S >> index 46fc0f4..b2f88cd 100644 >> --- a/arch/powerpc/kernel/entry_32.S >> +++ b/arch/powerpc/kernel/entry_32.S >> @@ -333,12 +333,12 @@ _GLOBAL(DoSyscall) >> lwz r11,TI_FLAGS(r10) >> andi. r11,r11,_TIF_SYSCALL_DOTRACE >> bne- syscall_dotrace >> -syscall_dotrace_cont: >> cmplwi 0,r0,NR_syscalls >> lis r10,sys_call_table@h >> ori r10,r10,sys_call_table@l >> slwi r0,r0,2 >> bge- 66f >> +syscall_dotrace_cont: >> lwzx r10,r10,r0 /* Fetch system call handler [ptr] */ >> mtlr r10 >> addi r9,r1,STACK_FRAME_OVERHEAD >> @@ -457,6 +457,11 @@ syscall_dotrace: >> lwz r7,GPR7(r1) >> lwz r8,GPR8(r1) >> REST_NVGPRS(r1) >> + cmplwi 0,r0,NR_syscalls >> + lis r10,sys_call_table@h >> + ori r10,r10,sys_call_table@l >> + slwi r0,r0,2 >> + bge- ret_from_syscall >> b syscall_dotrace_cont >> >> syscall_exit_work: >> diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S >> index d180caf2..0d22fa8 100644 >> --- a/arch/powerpc/kernel/entry_64.S >> +++ b/arch/powerpc/kernel/entry_64.S >> @@ -144,7 +144,6 @@ END_FW_FTR_SECTION_IFSET(FW_FEATURE_SPLPAR) >> ld r10,TI_FLAGS(r11) >> andi. r11,r10,_TIF_SYSCALL_DOTRACE >> bne syscall_dotrace >> -.Lsyscall_dotrace_cont: >> cmpldi 0,r0,NR_syscalls >> bge- syscall_enosys >> >> @@ -253,7 +252,9 @@ syscall_dotrace: >> addi r9,r1,STACK_FRAME_OVERHEAD >> CURRENT_THREAD_INFO(r10, r1) >> ld r10,TI_FLAGS(r10) >> - b .Lsyscall_dotrace_cont >> + cmpldi 0,r0,NR_syscalls >> + bge- syscall_exit > > Shouldn't this be .Lsyscall_exit?
Thanks for testing and spotting this! The kernel I tested with didn't have syscall_exit converted to a local label (commit 4c3b21686111e0ac6018469dacbc5549f9915cf8).
Will resend with this change.
Bogdan P.
>> + b system_call >> >> syscall_enosys: >> li r3,-ENOSYS >> diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c >> index f21897b..2edae06 100644 >> --- a/arch/powerpc/kernel/ptrace.c >> +++ b/arch/powerpc/kernel/ptrace.c >> @@ -1775,13 +1775,15 @@ long do_syscall_trace_enter(struct pt_regs *regs) >> secure_computing_strict(regs->gpr[0]); >> >> if (test_thread_flag(TIF_SYSCALL_TRACE) && >> - tracehook_report_syscall_entry(regs)) >> + tracehook_report_syscall_entry(regs)) { >> /* >> * Tracing decided this syscall should not happen. >> * We'll return a bogus call number to get an ENOSYS >> * error, but leave the original number in regs->gpr[0]. >> */ >> ret = -1L; >> + syscall_set_return_value(current, regs, ENOSYS, 0); >> + } >> >> if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT))) >> trace_sys_enter(regs, regs->gpr[0]); >> >
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