From: Dave Martin <Dave.Martin@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, marc.zyngier@arm.com,
catalin.marinas@arm.com, will.deacon@arm.com,
linux-kernel@vger.kernel.org, linux@dominikbrodowski.net,
james.morse@arm.com, viro@zeniv.linux.org.uk,
linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 07/18] arm64: remove sigreturn wrappers
Date: Mon, 14 May 2018 12:07:03 +0100 [thread overview]
Message-ID: <20180514110702.GD7753@e103592.cambridge.arm.com> (raw)
In-Reply-To: <20180514094640.27569-8-mark.rutland@arm.com>
On Mon, May 14, 2018 at 10:46:29AM +0100, Mark Rutland wrote:
> 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.
Hmmm, I always wondered why rt_sigreturn() et al. were handled
specially.
If there's effectively no underlying reason for that, it makes sense
to regularise the interface to these syscalls.
Tentatively-reviewed-by: Dave Martin <Dave.Martin@arm.com>
>
> 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
>
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2018-05-14 11:07 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 ` [PATCH 07/18] arm64: remove sigreturn wrappers Mark Rutland
2018-05-14 11:07 ` Dave Martin [this message]
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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