Hi all, On Sat, Oct 10, 2026 at 3:42 PM Magnus Lindholm <[email protected]> wrote: > > Enable the seccomp BPF selftests on Alpha with a fallback seccomp syscall > number and architecture-specific syscall register accessors. > > Use the NT_PRSTATUS register layout rather than struct pt_regs. The > register set contains r0-r30 followed by pc and unique. Read and update > the syscall number in r1, and set both r0 and the r19/a3 error flag when > synthesizing syscall results. > > At syscall entry, r19 still contains the fourth syscall argument, so > callers setting a synthetic return value must also set the syscall > number to -1 to skip execution. > > Signed-off-by: Magnus Lindholm <[email protected]> > Reviewed-by: Matt Turner <[email protected]> > --- > Changes in v3: > - Drop the /proc/self/syscall availability check and its commit-message > paragraph. Alpha selects HAVE_ARCH_TRACEHOOK. > - Document that setting r19/a3 at syscall entry requires callers to also > set the syscall number to -1. > - Add Matt Turner's Reviewed-by after addressing his review comments. > > Changes in v2: > - Use the NT_PRSTATUS layout for PTRACE_GETREGSET/PTRACE_SETREGSET. > - Set the Alpha return value and error flag together. > - Check for /proc/self/syscall at runtime (removed in v3). > > Validation on AlphaServer ES40, GCC 15.2.1, running > 7.3.0-rc1-es40-tsunami-v5a+: > - Standard v3 and the original baseline binary both report 98 pass, > 1 fail, 12 skip. The common failure is the 30-second timeout in > user_notification_wait_killable_after_reply. > - A separate diagnostic build extending only that test's timeout to > 180 seconds completes it in 34.938 seconds. The full diagnostic run > reports 99 pass, 0 fail, 12 skip. No timeout change is in this patch. > > tools/testing/selftests/seccomp/seccomp_bpf.c | 26 +++++++++++++++++++ > 1 file changed, 26 insertions(+) > > diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c > b/tools/testing/selftests/seccomp/seccomp_bpf.c > index 0622bc2..79e8eb3 100644 > --- a/tools/testing/selftests/seccomp/seccomp_bpf.c > +++ b/tools/testing/selftests/seccomp/seccomp_bpf.c > @@ -136,6 +136,8 @@ struct seccomp_data { > # define __NR_seccomp 354 > # elif defined(__x86_64__) > # define __NR_seccomp 317 > +# elif defined(__alpha__) > +# define __NR_seccomp 514 > # elif defined(__arm__) > # define __NR_seccomp 383 > # elif defined(__aarch64__) > @@ -1754,6 +1756,30 @@ TEST_F(TRACE_poke, getpid_runs_normally) > # define ARCH_REGS struct user_regs_struct > # define SYSCALL_NUM(_regs) (_regs).orig_eax > # define SYSCALL_RET(_regs) (_regs).eax > +#elif defined(__alpha__) > +/* NT_PRSTATUS contains r0-r30, pc and unique, not struct pt_regs. */ > +struct alpha_regs { > + unsigned long regs[33]; > +}; > + > +# define ARCH_REGS struct alpha_regs > +/* The kernel keeps the mutable syscall number in r1. */ > +# define SYSCALL_NUM(_regs) ((_regs).regs[1]) > +# define SYSCALL_RET(_regs) ((_regs).regs[0]) > +/* > + * Alpha returns positive errno in r0 with the r19/a3 error flag set. > + * At a syscall-entry stop, r19 is still the fourth syscall argument. > + * Callers must also set the syscall number to -1 to skip the syscall > + * before replacing r19 with the error flag. > + */ > +# define SYSCALL_RET_SET(_regs, _val) \ > + do { \ > + struct alpha_regs *__regs = &(_regs); \ > + long __ret = (_val); \ > + \ > + __regs->regs[0] = __ret < 0 ? -__ret : __ret; \ > + __regs->regs[19] = __ret < 0; \ > + } while (0) > #elif defined(__arm__) > # define ARCH_REGS struct pt_regs > # define SYSCALL_NUM(_regs) (_regs).ARM_r7 > -- > 2.43.0 >
Kees, Would you be OK with me taking this patch through my Alpha tree? The Alpha kernel support is already upstream. v3 carries Matt's Reviewed-by. On my ES40, it matches the baseline: 98 passes, 12 skips and one timeout. Extending that timeout gives 99 passes and 12 skips; that adjustment is not part of the patch. Link: https://lore.kernel.org/linux-alpha/[email protected]/ Thanks, Magnus
