RESEND [PATCH 1/6] arm64: compat: Use vDSO sigreturn trampolines if available

[Mark Salyzyn]

From: Kevin Brodsky <kevin.brod...@arm.com>

If the compat vDSO is enabled, it replaces the sigreturn page.
Therefore, we use the sigreturn trampolines the vDSO provides instead.

Signed-off-by: Kevin Brodsky <kevin.brod...@arm.com>
Signed-off-by: Mark Salyzyn <saly...@android.com>
Tested-by: Mark Salyzyn <saly...@android.com>
Cc: James Morse <james.mo...@arm.com>
Cc: Russell King <li...@armlinux.org.uk>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <will.dea...@arm.com>
Cc: Andy Lutomirski <l...@amacapital.net>
Cc: Dmitry Safonov <dsafo...@virtuozzo.com>
Cc: John Stultz <john.stu...@linaro.org>
Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: Laura Abbott <labb...@redhat.com>
Cc: Kees Cook <keesc...@chromium.org>
Cc: Ard Biesheuvel <ard.biesheu...@linaro.org>
Cc: Andy Gross <andy.gr...@linaro.org>
Cc: Andrew Pinski <apin...@cavium.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-ker...@lists.infradead.org
Cc: Jeremy Linton <jeremy.lin...@arm.com>
Cc: android-ker...@android.com
---
 arch/arm64/include/asm/vdso.h |  3 +++
 arch/arm64/kernel/signal32.c  | 15 +++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/arch/arm64/include/asm/vdso.h b/arch/arm64/include/asm/vdso.h
index 839ce0031bd5..f2a952338f1e 100644
--- a/arch/arm64/include/asm/vdso.h
+++ b/arch/arm64/include/asm/vdso.h
@@ -28,6 +28,9 @@
 #ifndef __ASSEMBLY__
 
 #include <generated/vdso-offsets.h>
+#ifdef CONFIG_VDSO32
+#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 6b421666b5b8..c3d9a74e3945 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -29,6 +29,7 @@
 #include <asm/traps.h>
 #include <linux/uaccess.h>
 #include <asm/unistd.h>
+#include <asm/vdso.h>
 
 struct compat_vfp_sigframe {
        compat_ulong_t  magic;
@@ -352,6 +353,19 @@ 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_VDSO32
+               void *vdso_base = current->mm->context.vdso;
+               void *trampoline =
+                       (ka->sa.sa_flags & SA_SIGINFO
+                        ? (thumb
+                           ? VDSO_SYMBOL(vdso_base, compat_rt_sigreturn_thumb)
+                           : VDSO_SYMBOL(vdso_base, compat_rt_sigreturn_arm))
+                        : (thumb
+                           ? VDSO_SYMBOL(vdso_base, compat_sigreturn_thumb)
+                           : VDSO_SYMBOL(vdso_base, compat_sigreturn_arm)));
+
+               retcode = ptr_to_compat(trampoline) + thumb;
+#else
                void *sigreturn_base = current->mm->context.vdso;
                unsigned int idx = thumb << 1;
 
@@ -359,6 +373,7 @@ static void compat_setup_return(struct pt_regs *regs, 
struct k_sigaction *ka,
                        idx += 3;
 
                retcode = ptr_to_compat(sigreturn_base) + (idx << 2) + thumb;
+#endif
        }
 
        regs->regs[0]   = usig;
-- 
2.19.0.605.g01d371f741-goog