diff options
| author |   Dave Martin <Dave.Martin@arm.com> | 2017-08-01 15:35:54 +0100 |
|---|---|---|
| committer |   Catalin Marinas <catalin.marinas@arm.com> | 2017-08-07 09:58:33 +0100 |
| commit | 17c28958600928109049a3bcc814b0d5bfb1ff3a (patch) | |
| tree | 901508d772cc2fe2b33013b01b59ca990bd8f6c5 /arch/arm64/kernel/entry.S | |
| parent | arm64: syscallno is secretly an int, make it official (diff) | |
| download | linux-dev-17c28958600928109049a3bcc814b0d5bfb1ff3a.tar.xz linux-dev-17c28958600928109049a3bcc814b0d5bfb1ff3a.zip | |
arm64: Abstract syscallno manipulation
The -1 "no syscall" value is written in various ways, shared with
the user ABI in some places, and generally obscure.
This patch attempts to make things a little more consistent and
readable by replacing all these uses with a single #define. A
couple of symbolic helpers are provided to clarify the intent
further.
Because the in-syscall check in do_signal() is changed from >= 0 to
!= NO_SYSCALL by this patch, different behaviour may be observable
if syscallno is set to values less than -1 by a tracer. However,
this is not different from the behaviour that is already observable
if a tracer sets syscallno to a value >= __NR_(compat_)syscalls.
It appears that this can cause spurious syscall restarting, but
that is not a new behaviour either, and does not appear harmful.
Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch/arm64/kernel/entry.S')
| -rw-r--r-- | arch/arm64/kernel/entry.S | 10 |
1 files changed, 4 insertions, 6 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 3bf0bd7a2f29..cace76d17535 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -138,11 +138,9 @@ alternative_else_nop_endif stp x22, x23, [sp, #S_PC] - /* - * Set syscallno to -1 by default (overridden later if real syscall). - */ + /* Not in a syscall by default (el0_svc overwrites for real syscall) */ .if \el == 0 - mvn w21, wzr + mov w21, #NO_SYSCALL str w21, [sp, #S_SYSCALLNO] .endif @@ -825,13 +823,13 @@ ENDPROC(el0_svc) * switches, and waiting for our parent to respond. */ __sys_trace: - cmp wscno, #-1 // user-issued syscall(-1)? + cmp wscno, #NO_SYSCALL // user-issued syscall(-1)? b.ne 1f mov x0, #-ENOSYS // set default errno if so str x0, [sp, #S_X0] 1: mov x0, sp bl syscall_trace_enter - cmp w0, #-1 // skip the syscall? + cmp w0, #NO_SYSCALL // skip the syscall? b.eq __sys_trace_return_skipped mov wscno, w0 // syscall number (possibly new) mov x1, sp // pointer to regs |