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    Subject[tip:timers/vdso] arm64: compat: Get sigreturn trampolines from vDSO
    Commit-ID:  f01703b3d2e6faf7233cedf78f1e2d31b39fa90f
    Gitweb: https://git.kernel.org/tip/f01703b3d2e6faf7233cedf78f1e2d31b39fa90f
    Author: Vincenzo Frascino <vincenzo.frascino@arm.com>
    AuthorDate: Fri, 21 Jun 2019 10:52:41 +0100
    Committer: Thomas Gleixner <tglx@linutronix.de>
    CommitDate: Sat, 22 Jun 2019 21:21:09 +0200

    arm64: compat: Get sigreturn trampolines from vDSO

    When the compat vDSO is enabled, the sigreturn trampolines are not
    anymore available through [sigpage] but through [vdso].

    Add the relevant code the enable the feature.

    Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Tested-by: Shijith Thotton <sthotton@marvell.com>
    Tested-by: Andre Przywara <andre.przywara@arm.com>
    Cc: linux-arch@vger.kernel.org
    Cc: linux-arm-kernel@lists.infradead.org
    Cc: linux-mips@vger.kernel.org
    Cc: linux-kselftest@vger.kernel.org
    Cc: Catalin Marinas <catalin.marinas@arm.com>
    Cc: Will Deacon <will.deacon@arm.com>
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: Russell King <linux@armlinux.org.uk>
    Cc: Ralf Baechle <ralf@linux-mips.org>
    Cc: Paul Burton <paul.burton@mips.com>
    Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
    Cc: Mark Salyzyn <salyzyn@android.com>
    Cc: Peter Collingbourne <pcc@google.com>
    Cc: Shuah Khan <shuah@kernel.org>
    Cc: Dmitry Safonov <0x7f454c46@gmail.com>
    Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
    Cc: Huw Davies <huw@codeweavers.com>
    Link: https://lkml.kernel.org/r/20190621095252.32307-15-vincenzo.frascino@arm.com

    ---
    arch/arm64/include/asm/vdso.h | 3 +++
    arch/arm64/kernel/signal32.c | 26 ++++++++++++++++++++++++++
    2 files changed, 29 insertions(+)

    diff --git a/arch/arm64/include/asm/vdso.h b/arch/arm64/include/asm/vdso.h
    index 1f94ec19903c..9c15e0a06301 100644
    --- a/arch/arm64/include/asm/vdso.h
    +++ b/arch/arm64/include/asm/vdso.h
    @@ -17,6 +17,9 @@
    #ifndef __ASSEMBLY__

    #include <generated/vdso-offsets.h>
    +#ifdef CONFIG_COMPAT_VDSO
    +#include <generated/vdso32-offsets.h>
    +#endif

    #define VDSO_SYMBOL(base, name) \
    ({ \
    diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
    index 8a9a5ceb63b7..12a585386c2f 100644
    --- a/arch/arm64/kernel/signal32.c
    +++ b/arch/arm64/kernel/signal32.c
    @@ -18,6 +18,7 @@
    #include <asm/traps.h>
    #include <linux/uaccess.h>
    #include <asm/unistd.h>
    +#include <asm/vdso.h>

    struct compat_vfp_sigframe {
    compat_ulong_t magic;
    @@ -341,6 +342,30 @@ static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,
    retcode = ptr_to_compat(ka->sa.sa_restorer);
    } else {
    /* Set up sigreturn pointer */
    +#ifdef CONFIG_COMPAT_VDSO
    + void *vdso_base = current->mm->context.vdso;
    + void *vdso_trampoline;
    +
    + if (ka->sa.sa_flags & SA_SIGINFO) {
    + if (thumb) {
    + vdso_trampoline = VDSO_SYMBOL(vdso_base,
    + compat_rt_sigreturn_thumb);
    + } else {
    + vdso_trampoline = VDSO_SYMBOL(vdso_base,
    + compat_rt_sigreturn_arm);
    + }
    + } else {
    + if (thumb) {
    + vdso_trampoline = VDSO_SYMBOL(vdso_base,
    + compat_sigreturn_thumb);
    + } else {
    + vdso_trampoline = VDSO_SYMBOL(vdso_base,
    + compat_sigreturn_arm);
    + }
    + }
    +
    + retcode = ptr_to_compat(vdso_trampoline) + thumb;
    +#else
    unsigned int idx = thumb << 1;

    if (ka->sa.sa_flags & SA_SIGINFO)
    @@ -348,6 +373,7 @@ static void compat_setup_return(struct pt_regs *regs, struct k_sigaction *ka,

    retcode = (unsigned long)current->mm->context.vdso +
    (idx << 2) + thumb;
    +#endif
    }

    regs->regs[0] = usig;
    \
     
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