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 10/18] arm64: convert native/compat syscall entry to C
Date: Mon, 14 May 2018 12:07:30 +0100 [thread overview]
Message-ID: <20180514110729.GF7753@e103592.cambridge.arm.com> (raw)
In-Reply-To: <20180514094640.27569-11-mark.rutland@arm.com>
On Mon, May 14, 2018 at 10:46:32AM +0100, Mark Rutland wrote:
> Now that the syscall invocation logic is in C, we can migrate the rest
> of the syscall entry logic over, so that the entry assembly needn't look
> at the register values at all.
>
> 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/kernel/entry.S | 42 ++++--------------------------------------
> arch/arm64/kernel/syscall.c | 40 ++++++++++++++++++++++++++++++++++++++--
> 2 files changed, 42 insertions(+), 40 deletions(-)
>
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 5c60369b52fc..13afefbf608f 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -690,14 +690,9 @@ el0_sync_compat:
> b.ge el0_dbg
> b el0_inv
> el0_svc_compat:
> - /*
> - * AArch32 syscall handling
> - */
> - ldr x16, [tsk, #TSK_TI_FLAGS] // load thread flags
> - adrp stbl, compat_sys_call_table // load compat syscall table pointer
> - mov wscno, w7 // syscall number in w7 (r7)
> - mov wsc_nr, #__NR_compat_syscalls
> - b el0_svc_naked
> + mov x0, sp
> + bl el0_svc_compat_handler
> + b ret_to_user
>
> .align 6
> el0_irq_compat:
> @@ -895,37 +890,8 @@ ENDPROC(ret_to_user)
> */
> .align 6
> el0_svc:
> - ldr x16, [tsk, #TSK_TI_FLAGS] // load thread flags
> - adrp stbl, sys_call_table // load syscall table pointer
> - mov wscno, w8 // syscall number in w8
> - mov wsc_nr, #__NR_syscalls
> -
> -#ifdef CONFIG_ARM64_SVE
> -alternative_if_not ARM64_SVE
> - b el0_svc_naked
> -alternative_else_nop_endif
> - tbz x16, #TIF_SVE, el0_svc_naked // Skip unless TIF_SVE set:
> - bic x16, x16, #_TIF_SVE // discard SVE state
> - str x16, [tsk, #TSK_TI_FLAGS]
> -
> - /*
> - * task_fpsimd_load() won't be called to update CPACR_EL1 in
> - * ret_to_user unless TIF_FOREIGN_FPSTATE is still set, which only
> - * happens if a context switch or kernel_neon_begin() or context
> - * modification (sigreturn, ptrace) intervenes.
> - * So, ensure that CPACR_EL1 is already correct for the fast-path case:
> - */
> - mrs x9, cpacr_el1
> - bic x9, x9, #CPACR_EL1_ZEN_EL0EN // disable SVE for el0
> - msr cpacr_el1, x9 // synchronised by eret to el0
> -#endif
> -
> -el0_svc_naked: // compat entry point
> mov x0, sp
> - mov w1, wscno
> - mov w2, wsc_nr
> - mov x3, stbl
> - bl el0_svc_common
> + bl el0_svc_handler
> b ret_to_user
> ENDPROC(el0_svc)
>
> diff --git a/arch/arm64/kernel/syscall.c b/arch/arm64/kernel/syscall.c
> index 5df857e32b48..4706f841e758 100644
> --- a/arch/arm64/kernel/syscall.c
> +++ b/arch/arm64/kernel/syscall.c
> @@ -6,7 +6,9 @@
> #include <linux/ptrace.h>
>
> #include <asm/daifflags.h>
> +#include <asm/fpsimd.h>
> #include <asm/thread_info.h>
> +#include <asm/unistd.h>
>
> long do_ni_syscall(struct pt_regs *regs);
>
> @@ -41,8 +43,8 @@ static inline bool has_syscall_work(unsigned long flags)
> int syscall_trace_enter(struct pt_regs *regs);
> void syscall_trace_exit(struct pt_regs *regs);
>
> -asmlinkage void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
> - syscall_fn_t syscall_table[])
> +static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
> + syscall_fn_t syscall_table[])
> {
> unsigned long flags = current_thread_info()->flags;
>
> @@ -79,3 +81,37 @@ asmlinkage void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
> trace_exit:
> syscall_trace_exit(regs);
> }
> +
> +static inline void sve_user_reset(void)
Static function with no caller...
> +{
> + if (!system_supports_sve())
> + return;
> +
> + /*
> + * task_fpsimd_load() won't be called to update CPACR_EL1 in
> + * ret_to_user unless TIF_FOREIGN_FPSTATE is still set, which only
> + * happens if a context switch or kernel_neon_begin() or context
> + * modification (sigreturn, ptrace) intervenes.
> + * So, ensure that CPACR_EL1 is already correct for the fast-path case.
> + */
> + if (test_and_clear_thread_flag(TIF_SVE))
> + sve_user_disable();
sve_user_disable() is already inline, and incorporates the if()
internally via sysreg_clear_set().
So, should this just be
clear_thread_flag(TIF_SVE);
sve_user_disable();
> +}
> +
> +extern syscall_fn_t sys_call_table[];
> +
> +asmlinkage void el0_svc_handler(struct pt_regs *regs)
> +{
if (system_supports_sve()) ?
> + sve_user_disable();
Or should this be replaced by a call to sve_user_reset()?
I suspect the latter, since we do want to be clearing TIF_SVE here too.
[...]
Cheers
---Dave
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
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 [this message]
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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