Commit 3b714275 authored by Mark Rutland's avatar Mark Rutland Committed by Will Deacon

arm64: convert native/compat syscall entry to C

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.

The SVE reset across syscall logic now unconditionally clears TIF_SVE,
but sve_user_disable() will only write back to CPACR_EL1 when SVE is
actually enabled.
Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
Reviewed-by: default avatarDave Martin <dave.martin@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarWill Deacon <will.deacon@arm.com>
parent f37099b6
...@@ -26,6 +26,10 @@ typedef long (*syscall_fn_t)(unsigned long, unsigned long, ...@@ -26,6 +26,10 @@ typedef long (*syscall_fn_t)(unsigned long, unsigned long,
extern const syscall_fn_t sys_call_table[]; extern const syscall_fn_t sys_call_table[];
#ifdef CONFIG_COMPAT
extern const syscall_fn_t compat_sys_call_table[];
#endif
static inline int syscall_get_nr(struct task_struct *task, static inline int syscall_get_nr(struct task_struct *task,
struct pt_regs *regs) struct pt_regs *regs)
{ {
......
...@@ -720,14 +720,9 @@ el0_sync_compat: ...@@ -720,14 +720,9 @@ el0_sync_compat:
b.ge el0_dbg b.ge el0_dbg
b el0_inv b el0_inv
el0_svc_compat: el0_svc_compat:
/* mov x0, sp
* AArch32 syscall handling bl el0_svc_compat_handler
*/ b ret_to_user
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
.align 6 .align 6
el0_irq_compat: el0_irq_compat:
...@@ -925,37 +920,8 @@ ENDPROC(ret_to_user) ...@@ -925,37 +920,8 @@ ENDPROC(ret_to_user)
*/ */
.align 6 .align 6
el0_svc: 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 x0, sp
mov w1, wscno bl el0_svc_handler
mov w2, wsc_nr
mov x3, stbl
bl el0_svc_common
b ret_to_user b ret_to_user
ENDPROC(el0_svc) ENDPROC(el0_svc)
......
...@@ -8,8 +8,10 @@ ...@@ -8,8 +8,10 @@
#include <linux/syscalls.h> #include <linux/syscalls.h>
#include <asm/daifflags.h> #include <asm/daifflags.h>
#include <asm/fpsimd.h>
#include <asm/syscall.h> #include <asm/syscall.h>
#include <asm/thread_info.h> #include <asm/thread_info.h>
#include <asm/unistd.h>
long compat_arm_syscall(struct pt_regs *regs); long compat_arm_syscall(struct pt_regs *regs);
...@@ -58,8 +60,8 @@ static inline bool has_syscall_work(unsigned long flags) ...@@ -58,8 +60,8 @@ static inline bool has_syscall_work(unsigned long flags)
int syscall_trace_enter(struct pt_regs *regs); int syscall_trace_enter(struct pt_regs *regs);
void syscall_trace_exit(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, static void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
const syscall_fn_t syscall_table[]) const syscall_fn_t syscall_table[])
{ {
unsigned long flags = current_thread_info()->flags; unsigned long flags = current_thread_info()->flags;
...@@ -96,3 +98,34 @@ asmlinkage void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr, ...@@ -96,3 +98,34 @@ asmlinkage void el0_svc_common(struct pt_regs *regs, int scno, int sc_nr,
trace_exit: trace_exit:
syscall_trace_exit(regs); syscall_trace_exit(regs);
} }
static inline void sve_user_discard(void)
{
if (!system_supports_sve())
return;
clear_thread_flag(TIF_SVE);
/*
* 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.
*/
sve_user_disable();
}
asmlinkage void el0_svc_handler(struct pt_regs *regs)
{
sve_user_discard();
el0_svc_common(regs, regs->regs[8], __NR_syscalls, sys_call_table);
}
#ifdef CONFIG_COMPAT
asmlinkage void el0_svc_compat_handler(struct pt_regs *regs)
{
el0_svc_common(regs, regs->regs[7], __NR_compat_syscalls,
compat_sys_call_table);
}
#endif
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