[PATCH v6 14/19] arm64: compat: Get sigreturn trampolines from vDSO

Vincenzo Frascino
2019-05-30T14:16:36Z

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.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Vincenzo Frascino <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 839ce0031bd5..9b197e5ea759 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_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 74e06d8c7c2b..4fca2e1937b2 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 +353,30 @@ 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)
@@ -359,6 +384,7 @@ 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;
--
2.21.0