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From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org, catalin.marinas@arm.com,
	dave.martin@arm.com, james.morse@arm.com,
	linux@dominikbrodowski.net, linux-fsdevel@vger.kernel.org,
	marc.zyngier@arm.com, mark.rutland@arm.com,
	viro@zeniv.linux.org.uk, will.deacon@arm.com
Subject: [PATCH 07/18] arm64: remove sigreturn wrappers
Date: Mon, 14 May 2018 10:46:29 +0100	[thread overview]
Message-ID: <20180514094640.27569-8-mark.rutland@arm.com> (raw)
In-Reply-To: <20180514094640.27569-1-mark.rutland@arm.com>

The arm64 sigreturn* syscall handlers are non-standard. Rather than
taking a number of user parameters in registers as per the AAPCS,
they expect the pt_regs as their sole argument.

To make this work, we override the syscall definitions to invoke
wrappers written in assembly, which mov the SP into x0, and branch to
their respective C functions.

On other architectures (such as x86), the sigreturn* functions take no
argument and instead use current_pt_regs() to acquire the user
registers. This requires less boilerplate code, and allows for other
features such as interposing C code in this path.

This patch takes the same approach for arm64.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
---
 arch/arm64/include/asm/unistd32.h |  4 ++--
 arch/arm64/kernel/entry.S         |  8 --------
 arch/arm64/kernel/entry32.S       | 10 ----------
 arch/arm64/kernel/signal.c        |  3 ++-
 arch/arm64/kernel/signal32.c      |  6 ++++--
 arch/arm64/kernel/sys.c           |  3 +--
 arch/arm64/kernel/sys32.c         |  4 ++--
 7 files changed, 11 insertions(+), 27 deletions(-)

diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h
index ef292160748c..ab95554b1734 100644
--- a/arch/arm64/include/asm/unistd32.h
+++ b/arch/arm64/include/asm/unistd32.h
@@ -260,7 +260,7 @@ __SYSCALL(117, sys_ni_syscall)
 #define __NR_fsync 118
 __SYSCALL(__NR_fsync, sys_fsync)
 #define __NR_sigreturn 119
-__SYSCALL(__NR_sigreturn, compat_sys_sigreturn_wrapper)
+__SYSCALL(__NR_sigreturn, compat_sys_sigreturn)
 #define __NR_clone 120
 __SYSCALL(__NR_clone, sys_clone)
 #define __NR_setdomainname 121
@@ -368,7 +368,7 @@ __SYSCALL(__NR_getresgid, sys_getresgid16)
 #define __NR_prctl 172
 __SYSCALL(__NR_prctl, sys_prctl)
 #define __NR_rt_sigreturn 173
-__SYSCALL(__NR_rt_sigreturn, compat_sys_rt_sigreturn_wrapper)
+__SYSCALL(__NR_rt_sigreturn, compat_sys_rt_sigreturn)
 #define __NR_rt_sigaction 174
 __SYSCALL(__NR_rt_sigaction, compat_sys_rt_sigaction)
 #define __NR_rt_sigprocmask 175
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index ec2ee720e33e..08ea3cbfb08f 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -1108,14 +1108,6 @@ __entry_tramp_data_start:
 #endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
 
 /*
- * Special system call wrappers.
- */
-ENTRY(sys_rt_sigreturn_wrapper)
-	mov	x0, sp
-	b	sys_rt_sigreturn
-ENDPROC(sys_rt_sigreturn_wrapper)
-
-/*
  * Register switch for AArch64. The callee-saved registers need to be saved
  * and restored. On entry:
  *   x0 = previous task_struct (must be preserved across the switch)
diff --git a/arch/arm64/kernel/entry32.S b/arch/arm64/kernel/entry32.S
index f332d5d1f6b4..f9461696dde4 100644
--- a/arch/arm64/kernel/entry32.S
+++ b/arch/arm64/kernel/entry32.S
@@ -30,16 +30,6 @@
  * System call wrappers for the AArch32 compatibility layer.
  */
 
-ENTRY(compat_sys_sigreturn_wrapper)
-	mov	x0, sp
-	b	compat_sys_sigreturn
-ENDPROC(compat_sys_sigreturn_wrapper)
-
-ENTRY(compat_sys_rt_sigreturn_wrapper)
-	mov	x0, sp
-	b	compat_sys_rt_sigreturn
-ENDPROC(compat_sys_rt_sigreturn_wrapper)
-
 ENTRY(compat_sys_statfs64_wrapper)
 	mov	w3, #84
 	cmp	w1, #88
diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 8e624fec4707..caa7a68cf2d2 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -538,8 +538,9 @@ static int restore_sigframe(struct pt_regs *regs,
 	return err;
 }
 
-asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
+asmlinkage long sys_rt_sigreturn(void)
 {
+	struct pt_regs *regs = current_pt_regs();
 	struct rt_sigframe __user *frame;
 
 	/* Always make any pending restarted system calls return -EINTR */
diff --git a/arch/arm64/kernel/signal32.c b/arch/arm64/kernel/signal32.c
index 77b91f478995..cb10588a7cb2 100644
--- a/arch/arm64/kernel/signal32.c
+++ b/arch/arm64/kernel/signal32.c
@@ -282,8 +282,9 @@ static int compat_restore_sigframe(struct pt_regs *regs,
 	return err;
 }
 
-asmlinkage int compat_sys_sigreturn(struct pt_regs *regs)
+asmlinkage int compat_sys_sigreturn(void)
 {
+	struct pt_regs *regs = current_pt_regs();
 	struct compat_sigframe __user *frame;
 
 	/* Always make any pending restarted system calls return -EINTR */
@@ -312,8 +313,9 @@ asmlinkage int compat_sys_sigreturn(struct pt_regs *regs)
 	return 0;
 }
 
-asmlinkage int compat_sys_rt_sigreturn(struct pt_regs *regs)
+asmlinkage int compat_sys_rt_sigreturn(void)
 {
+	struct pt_regs *regs = current_pt_regs();
 	struct compat_rt_sigframe __user *frame;
 
 	/* Always make any pending restarted system calls return -EINTR */
diff --git a/arch/arm64/kernel/sys.c b/arch/arm64/kernel/sys.c
index 72981bae10eb..31045f3fed92 100644
--- a/arch/arm64/kernel/sys.c
+++ b/arch/arm64/kernel/sys.c
@@ -48,8 +48,7 @@ SYSCALL_DEFINE1(arm64_personality, unsigned int, personality)
 /*
  * Wrappers to pass the pt_regs argument.
  */
-asmlinkage long sys_rt_sigreturn_wrapper(void);
-#define sys_rt_sigreturn	sys_rt_sigreturn_wrapper
+asmlinkage long sys_rt_sigreturn(void);
 #define sys_personality		sys_arm64_personality
 
 #undef __SYSCALL
diff --git a/arch/arm64/kernel/sys32.c b/arch/arm64/kernel/sys32.c
index a40b1343b819..1ef103c95410 100644
--- a/arch/arm64/kernel/sys32.c
+++ b/arch/arm64/kernel/sys32.c
@@ -25,8 +25,8 @@
 #include <linux/compiler.h>
 #include <linux/syscalls.h>
 
-asmlinkage long compat_sys_sigreturn_wrapper(void);
-asmlinkage long compat_sys_rt_sigreturn_wrapper(void);
+asmlinkage long compat_sys_sigreturn(void);
+asmlinkage long compat_sys_rt_sigreturn(void);
 asmlinkage long compat_sys_statfs64_wrapper(void);
 asmlinkage long compat_sys_fstatfs64_wrapper(void);
 asmlinkage long compat_sys_pread64_wrapper(void);
-- 
2.11.0

  parent reply	other threads:[~2018-05-14  9:47 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-05-14  9:46 [PATCH 00/18] arm64: invoke syscalls with pt_regs Mark Rutland
2018-05-14  9:46 ` [PATCH 01/18] arm64: consistently use unsigned long for thread flags Mark Rutland
2018-05-14  9:57   ` Dave Martin
2018-05-14  9:46 ` [PATCH 02/18] arm64: move SCTLR_EL{1,2} assertions to <asm/sysreg.h> Mark Rutland
2018-05-14 10:00   ` Dave Martin
2018-05-14 10:08     ` Mark Rutland
2018-05-14 11:20       ` Dave Martin
2018-05-14 11:56         ` Robin Murphy
2018-05-14 12:06           ` Mark Rutland
2018-05-14 12:41             ` Dave Martin
2018-05-14 13:10               ` Mark Rutland
2018-05-14  9:46 ` [PATCH 03/18] arm64: introduce sysreg_clear_set() Mark Rutland
2018-05-14 10:04   ` Dave Martin
2018-05-14  9:46 ` [PATCH 04/18] arm64: kill config_sctlr_el1() Mark Rutland
2018-05-14 10:05   ` Dave Martin
2018-05-14  9:46 ` [PATCH 05/18] arm64: kill change_cpacr() Mark Rutland
2018-05-14 10:06   ` Dave Martin
2018-05-14  9:46 ` [PATCH 06/18] arm64: move sve_user_{enable,disable} to <asm/fpsimd.h> Mark Rutland
2018-05-14 11:06   ` [PATCH 06/18] arm64: move sve_user_{enable, disable} " Dave Martin
2018-05-15 10:39     ` Mark Rutland
2018-05-15 12:19       ` Dave Martin
2018-05-15 16:33         ` Mark Rutland
2018-05-16  9:01           ` Dave Martin
2018-06-01 10:29             ` Mark Rutland
2018-06-01 10:42               ` Dave Martin
2018-05-14  9:46 ` Mark Rutland [this message]
2018-05-14 11:07   ` [PATCH 07/18] arm64: remove sigreturn wrappers Dave Martin
2018-05-14  9:46 ` [PATCH 08/18] arm64: convert raw syscall invocation to C Mark Rutland
2018-05-14 11:07   ` Dave Martin
2018-05-14 11:41     ` Mark Rutland
2018-05-14 12:53       ` Dave Martin
2018-05-14 20:24       ` Dominik Brodowski
2018-05-15  8:22         ` Mark Rutland
2018-05-15 10:01           ` Dominik Brodowski
2018-05-15 10:13             ` Mark Rutland
2018-05-14 18:00   ` Dominik Brodowski
2018-05-15  8:18     ` Mark Rutland
2018-05-14  9:46 ` [PATCH 09/18] arm64: convert syscall trace logic " Mark Rutland
2018-05-14  9:46 ` [PATCH 10/18] arm64: convert native/compat syscall entry " Mark Rutland
2018-05-14 11:07   ` Dave Martin
2018-05-14 11:58     ` Mark Rutland
2018-05-14 14:43       ` Dave Martin
2018-05-14 15:01         ` Mark Rutland
2018-05-14  9:46 ` [PATCH 11/18] arm64: zero GPRs upon entry from EL0 Mark Rutland
2018-05-14 11:07   ` Dave Martin
2018-05-14  9:46 ` [PATCH 12/18] kernel: add ksys_personality() Mark Rutland
2018-05-14 11:08   ` Dave Martin
2018-05-14 12:07   ` Christoph Hellwig
2018-05-15  9:56     ` Mark Rutland
2018-05-14  9:46 ` [PATCH 13/18] kernel: add kcompat_sys_{f,}statfs64() Mark Rutland
2018-05-14 17:14   ` Mark Rutland
2018-05-14 20:34     ` Dominik Brodowski
2018-05-15  9:53       ` Mark Rutland
2018-05-15  9:58         ` Dominik Brodowski
2018-05-14  9:46 ` [PATCH 14/18] arm64: remove in-kernel call to sys_personality() Mark Rutland
2018-05-14  9:46 ` [PATCH 15/18] arm64: use {COMPAT,}SYSCALL_DEFINE0 for sigreturn Mark Rutland
2018-05-14  9:46 ` [PATCH 16/18] arm64: use SYSCALL_DEFINE6() for mmap Mark Rutland
2018-05-14  9:46 ` [PATCH 17/18] arm64: convert compat wrappers to C Mark Rutland
2018-05-14 12:10   ` Christoph Hellwig
2018-05-14 12:43     ` Mark Rutland
2018-05-14  9:46 ` [PATCH 18/18] arm64: implement syscall wrappers Mark Rutland
2018-05-14 20:57   ` Dominik Brodowski
2018-05-15  8:37     ` Mark Rutland

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