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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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