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

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Message-Id: <20181001175845.168430-19-salyzyn@android.com>
Date:   Mon,  1 Oct 2018 10:58:38 -0700
From:   Mark Salyzyn <salyzyn@...roid.com>
To:     linux-kernel@...r.kernel.org
Cc:     Kevin Brodsky <kevin.brodsky@....com>,
        Mark Salyzyn <salyzyn@...roid.com>,
        James Morse <james.morse@....com>,
        Russell King <linux@...linux.org.uk>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Andy Lutomirski <luto@...capital.net>,
        Dmitry Safonov <dsafonov@...tuozzo.com>,
        John Stultz <john.stultz@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Laura Abbott <labbott@...hat.com>,
        Kees Cook <keescook@...omium.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Andy Gross <andy.gross@...aro.org>,
        Andrew Pinski <apinski@...ium.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-arm-kernel@...ts.infradead.org,
        Jeremy Linton <Jeremy.Linton@....com>,
        android-kernel@...roid.com, Dave Martin <Dave.Martin@....com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: RESEND [PATCH 1/6] arm64: compat: Use vDSO sigreturn trampolines if available

From: Kevin Brodsky <kevin.brodsky@....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.brodsky@....com>
Signed-off-by: Mark Salyzyn <salyzyn@...roid.com>
Tested-by: Mark Salyzyn <salyzyn@...roid.com>
Cc: James Morse <james.morse@....com>
Cc: Russell King <linux@...linux.org.uk>
Cc: Catalin Marinas <catalin.marinas@....com>
Cc: Will Deacon <will.deacon@....com>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Dmitry Safonov <dsafonov@...tuozzo.com>
Cc: John Stultz <john.stultz@...aro.org>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Laura Abbott <labbott@...hat.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Ard Biesheuvel <ard.biesheuvel@...aro.org>
Cc: Andy Gross <andy.gross@...aro.org>
Cc: Andrew Pinski <apinski@...ium.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-kernel@...r.kernel.org
Cc: linux-arm-kernel@...ts.infradead.org
Cc: Jeremy Linton <Jeremy.Linton@....com>
Cc: android-kernel@...roid.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