[RFC PATCH] arm64: signal: Make parse_user_sigframe() independent of rt_sigframe layout
Yury Norov
ynorov at caviumnetworks.com
Sun Jun 25 08:05:44 PDT 2017
On Fri, Jun 23, 2017 at 10:07:39AM +0100, Dave Martin wrote:
> ILP32 support uses the same struct sigcontext as the native ABI
> (i.e., LP64), but a different layout for the rest of the signal
> frame (since siginfo_t and ucontext_t are both ABI-dependent).
>
> Since the purpose of parse_user_sigframe() is really to parse
> sigcontext and not the whole signal frame, the function does not
> need to depend on the layout of rt_sigframe -- the only purpose of
> the rt_sigframe pointer is for use as a base to measure the signal
> frame size.
>
> So, this patch renames the function to parse_user_sigcontext() and
> makes the sigframe base pointer generic. ABI-specific parsers that
> share the same sigcontext definition can then call it.
>
> To minimise churn in this patch, the native LP64 parser is retained
> under the old name, but becomes a call to parse_user_sigconext().
> It may make sense instead to fold this into its restore_sigframe(),
> depending on how ILP32 support is integrated.
>
> Suggested-by: Yury Norov <ynorov at caviumnetworks.com>
> Signed-off-by: Dave Martin <Dave.Martin at arm.com>
> ---
>
> This patch depends on [1], which does not appear to be applied yet.
>
> [1] [PATCH] arm64: signal: Allow expansion of the signal frame http://lists.infradead.org/pipermail/linux-arm-kernel/2017-June/514699.html
>
> arch/arm64/kernel/signal.c | 14 ++++++++++----
> 1 file changed, 10 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
> index e47cd3a..a189321 100644
> --- a/arch/arm64/kernel/signal.c
> +++ b/arch/arm64/kernel/signal.c
> @@ -223,16 +223,16 @@ struct user_ctxs {
> struct fpsimd_context __user *fpsimd;
> };
>
> -static int parse_user_sigframe(struct user_ctxs *user,
> - struct rt_sigframe __user *sf)
> +static int parse_user_sigcontext(struct user_ctxs *user,
> + struct sigcontext __user const *sc,
> + void __user const *sigframe_base)
> {
> - struct sigcontext __user *const sc = &sf->uc.uc_mcontext;
> struct _aarch64_ctx __user *head;
> char __user *base = (char __user *)&sc->__reserved;
> size_t offset = 0;
> size_t limit = sizeof(sc->__reserved);
> bool have_extra_context = false;
> - char const __user *const sfp = (char const __user *)sf;
> + char const __user *const sfp = (char const __user *)sigframe_base;
>
> user->fpsimd = NULL;
>
> @@ -366,6 +366,12 @@ static int parse_user_sigframe(struct user_ctxs *user,
> return -EINVAL;
> }
>
> +static int parse_user_sigframe(struct user_ctxs *user,
> + struct rt_sigframe __user const *sf)
> +{
> + return parse_user_sigcontext(user, &sf->uc.uc_mcontext, sf);
> +}
> +
Hi Dave,
Thank you. Seems this is what I need. Only one thing. We can #define
parse_user_sigframe() as macro, and so bypass type control.
The macro then will be used both by lp64 and ilp32 without any
modification.
Yury
> static int restore_sigframe(struct pt_regs *regs,
> struct rt_sigframe __user *sf)
> {
> --
> 2.1.4
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