* [PATCH v3] selftests/seccomp: add Alpha support to seccomp_bpf
@ 2026-10-10 13:42 Magnus Lindholm
2026-10-10 16:24 ` Magnus Lindholm
0 siblings, 1 reply; 3+ messages in thread
From: Magnus Lindholm @ 2026-10-10 13:42 UTC (permalink / raw)
To: richard.henderson, mattst88, linux-kernel, linux-alpha; +Cc: linmag7
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 <linmag7@gmail.com>
Reviewed-by: Matt Turner <mattst88@gmail.com>
---
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
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v3] selftests/seccomp: add Alpha support to seccomp_bpf
2026-10-10 13:42 [PATCH v3] selftests/seccomp: add Alpha support to seccomp_bpf Magnus Lindholm
@ 2026-10-10 16:24 ` Magnus Lindholm
2026-10-10 17:04 ` Kees Cook
0 siblings, 1 reply; 3+ messages in thread
From: Magnus Lindholm @ 2026-10-10 16:24 UTC (permalink / raw)
To: richard.henderson, mattst88, linux-kernel, linux-alpha, Kees Cook
Cc: Shuah Khan, wad, linux-kselftest
Hi all,
On Sat, Oct 10, 2026 at 3:42 PM Magnus Lindholm <linmag7@gmail.com> 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 <linmag7@gmail.com>
> Reviewed-by: Matt Turner <mattst88@gmail.com>
> ---
> 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/20261010134214.974565-1-linmag7@gmail.com/
Thanks,
Magnus
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [PATCH v3] selftests/seccomp: add Alpha support to seccomp_bpf
2026-10-10 16:24 ` Magnus Lindholm
@ 2026-10-10 17:04 ` Kees Cook
0 siblings, 0 replies; 3+ messages in thread
From: Kees Cook @ 2026-10-10 17:04 UTC (permalink / raw)
To: Magnus Lindholm, richard.henderson, mattst88, linux-kernel, linux-alpha
Cc: Shuah Khan, wad, linux-kselftest
On October 10, 2026 9:24:16 AM PDT, Magnus Lindholm <linmag7@gmail.com> wrote:
>Hi all,
>
>On Sat, Oct 10, 2026 at 3:42 PM Magnus Lindholm <linmag7@gmail.com> 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 <linmag7@gmail.com>
>> Reviewed-by: Matt Turner <mattst88@gmail.com>
>> ---
>> 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/20261010134214.974565-1-linmag7@gmail.com/
>
>Thanks,
>Magnus
Yup, totally fine. Thank you!
-Kees
--
Kees Cook
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-10-10 16:24 ` Magnus Lindholm
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