Le 25/02/2020 à 18:35, Nicholas Piggin a écrit :
System call entry and particularly exit code is beyond the limit of what
is reasonable to implement in asm.
This conversion moves all conditional branches out of the asm code,
except for the case that all GPRs should be restored at exit.
Null syscall test is about 5% faster after this patch, because the exit
work is handled under local_irq_disable, and the hard mask and pending
interrupt replay is handled after that, which avoids games with MSR.
Signed-off-by: Nicholas Piggin <npig...@gmail.com>
Signed-off-by: Michal Suchanek <msucha...@suse.de>
---
v2,rebase (from Michal):
- Add endian conversion for dtl_idx (ms)
- Fix sparse warning about missing declaration (ms)
- Add unistd.h to fix some defconfigs, add SPDX, minor formatting (mpe)
v3: Fixes thanks to reports from mpe and selftests errors:
- Several soft-mask debug and unsafe smp_processor_id() warnings due to
tracing and other false positives due to checks in "unreconciled" code.
- Fix a bug with syscall tracing functions that set registers (e.g.,
PTRACE_SETREG) not setting GPRs properly.
- Fix silly tabort_syscall bug that causes kernel crashes when making system
calls in transactional state.
arch/powerpc/include/asm/asm-prototypes.h | 17 +-
.../powerpc/include/asm/book3s/64/kup-radix.h | 14 +-
arch/powerpc/include/asm/cputime.h | 29 ++
arch/powerpc/include/asm/hw_irq.h | 4 +
arch/powerpc/include/asm/ptrace.h | 3 +
arch/powerpc/include/asm/signal.h | 3 +
arch/powerpc/include/asm/switch_to.h | 5 +
arch/powerpc/include/asm/time.h | 3 +
arch/powerpc/kernel/Makefile | 3 +-
arch/powerpc/kernel/entry_64.S | 338 +++---------------
arch/powerpc/kernel/signal.h | 2 -
arch/powerpc/kernel/syscall_64.c | 213 +++++++++++
arch/powerpc/kernel/systbl.S | 9 +-
13 files changed, 328 insertions(+), 315 deletions(-)
create mode 100644 arch/powerpc/kernel/syscall_64.c
diff --git a/arch/powerpc/include/asm/asm-prototypes.h
b/arch/powerpc/include/asm/asm-prototypes.h
index 983c0084fb3f..4b3609554e76 100644
--- a/arch/powerpc/include/asm/asm-prototypes.h
+++ b/arch/powerpc/include/asm/asm-prototypes.h
@@ -97,6 +97,12 @@ ppc_select(int n, fd_set __user *inp, fd_set __user *outp,
fd_set __user *exp,
unsigned long __init early_init(unsigned long dt_ptr);
void __init machine_init(u64 dt_ptr);
#endif
+#ifdef CONFIG_PPC64
This ifdef is not necessary as it has no pending #else.
Having function declaration without definition is not an issue.
Keeping in mind that we are aiming at generalising this to PPC32.
+long system_call_exception(long r3, long r4, long r5, long r6, long r7, long
r8, unsigned long r0, struct pt_regs *regs);
+notrace unsigned long syscall_exit_prepare(unsigned long r3, struct pt_regs
*regs);
+notrace unsigned long interrupt_exit_user_prepare(struct pt_regs *regs,
unsigned long msr);
+notrace unsigned long interrupt_exit_kernel_prepare(struct pt_regs *regs,
unsigned long msr);
+#endif
long ppc_fadvise64_64(int fd, int advice, u32 offset_high, u32 offset_low,
u32 len_high, u32 len_low);
@@ -104,14 +110,6 @@ long sys_switch_endian(void);
notrace unsigned int __check_irq_replay(void);
void notrace restore_interrupts(void);
-/* ptrace */
-long do_syscall_trace_enter(struct pt_regs *regs);
-void do_syscall_trace_leave(struct pt_regs *regs);
-
-/* process */
-void restore_math(struct pt_regs *regs);
-void restore_tm_state(struct pt_regs *regs);
-
/* prom_init (OpenFirmware) */
unsigned long __init prom_init(unsigned long r3, unsigned long r4,
unsigned long pp,
@@ -122,9 +120,6 @@ unsigned long __init prom_init(unsigned long r3, unsigned
long r4,
void __init early_setup(unsigned long dt_ptr);
void early_setup_secondary(void);
-/* time */
-void accumulate_stolen_time(void);
-
/* misc runtime */
extern u64 __bswapdi2(u64);
extern s64 __lshrdi3(s64, int);
diff --git a/arch/powerpc/include/asm/book3s/64/kup-radix.h
b/arch/powerpc/include/asm/book3s/64/kup-radix.h
index 90dd3a3fc8c7..71081d90f999 100644
--- a/arch/powerpc/include/asm/book3s/64/kup-radix.h
+++ b/arch/powerpc/include/asm/book3s/64/kup-radix.h
@@ -3,6 +3,7 @@
#define _ASM_POWERPC_BOOK3S_64_KUP_RADIX_H
#include <linux/const.h>
+#include <asm/reg.h>
#define AMR_KUAP_BLOCK_READ UL(0x4000000000000000)
#define AMR_KUAP_BLOCK_WRITE UL(0x8000000000000000)
@@ -56,7 +57,14 @@
#ifdef CONFIG_PPC_KUAP
-#include <asm/reg.h>
+#include <asm/mmu.h>
+#include <asm/ptrace.h>
+
+static inline void kuap_check_amr(void)
+{
+ if (IS_ENABLED(CONFIG_PPC_KUAP_DEBUG) &&
mmu_has_feature(MMU_FTR_RADIX_KUAP))
+ WARN_ON_ONCE(mfspr(SPRN_AMR) != AMR_KUAP_BLOCKED);
+}
/*
* We support individually allowing read or write, but we don't support
nesting
@@ -127,6 +135,10 @@ bad_kuap_fault(struct pt_regs *regs, unsigned long
address, bool is_write)
(regs->kuap & (is_write ? AMR_KUAP_BLOCK_WRITE :
AMR_KUAP_BLOCK_READ)),
"Bug: %s fault blocked by AMR!", is_write ? "Write" :
"Read");
}
+#else /* CONFIG_PPC_KUAP */
+static inline void kuap_check_amr(void)
+{
+}
#endif /* CONFIG_PPC_KUAP */
#endif /* __ASSEMBLY__ */
diff --git a/arch/powerpc/include/asm/cputime.h
b/arch/powerpc/include/asm/cputime.h
index 2431b4ada2fa..6639a6847cc0 100644
--- a/arch/powerpc/include/asm/cputime.h
+++ b/arch/powerpc/include/asm/cputime.h
@@ -44,6 +44,28 @@ static inline unsigned long cputime_to_usecs(const cputime_t
ct)
#ifdef CONFIG_PPC64
#define get_accounting(tsk) (&get_paca()->accounting)
static inline void arch_vtime_task_switch(struct task_struct *tsk) { }
Could we have the below additions sit outside of this PPC64 ifdef, to be
reused on PPC32 ?
+
+/*
+ * account_cpu_user_entry/exit runs "unreconciled", so can't trace,
+ * can't use use get_paca()
+ */
+static notrace inline void account_cpu_user_entry(void)
+{
+ unsigned long tb = mftb();
+ struct cpu_accounting_data *acct = &local_paca->accounting;
In the spirit of reusing that code on PPC32, can we use get_accounting()
? Or an alternate version of get_accounting(), eg
get_accounting_notrace() to be defined ?
+
+ acct->utime += (tb - acct->starttime_user);
+ acct->starttime = tb;
+}
+static notrace inline void account_cpu_user_exit(void)
+{
+ unsigned long tb = mftb();
+ struct cpu_accounting_data *acct = &local_paca->accounting;
+
+ acct->stime += (tb - acct->starttime);
+ acct->starttime_user = tb;
+}
+
#else
#define get_accounting(tsk) (&task_thread_info(tsk)->accounting)
/*
@@ -61,5 +83,12 @@ static inline void arch_vtime_task_switch(struct task_struct
*prev)
#endif
#endif /* __KERNEL__ */
+#else /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
+static inline void account_cpu_user_entry(void)
+{
+}
+static inline void account_cpu_user_exit(void)
+{
+}
#endif /* CONFIG_VIRT_CPU_ACCOUNTING_NATIVE */
#endif /* __POWERPC_CPUTIME_H */
diff --git a/arch/powerpc/include/asm/hw_irq.h
b/arch/powerpc/include/asm/hw_irq.h
index e3a905e3d573..310583e62bd9 100644
--- a/arch/powerpc/include/asm/hw_irq.h
+++ b/arch/powerpc/include/asm/hw_irq.h
@@ -228,9 +228,13 @@ static inline bool arch_irqs_disabled(void)
#ifdef CONFIG_PPC_BOOK3E
#define __hard_irq_enable() wrtee(MSR_EE)
#define __hard_irq_disable() wrtee(0)
+#define __hard_EE_RI_disable() wrtee(0)
+#define __hard_RI_enable() do { } while (0)
#else
#define __hard_irq_enable() __mtmsrd(MSR_EE|MSR_RI, 1)
#define __hard_irq_disable() __mtmsrd(MSR_RI, 1)
+#define __hard_EE_RI_disable() __mtmsrd(0, 1)
+#define __hard_RI_enable() __mtmsrd(MSR_RI, 1)
#endif
#define hard_irq_disable() do { \
diff --git a/arch/powerpc/include/asm/ptrace.h
b/arch/powerpc/include/asm/ptrace.h
index ee3ada66deb5..082a40153b94 100644
--- a/arch/powerpc/include/asm/ptrace.h
+++ b/arch/powerpc/include/asm/ptrace.h
@@ -138,6 +138,9 @@ extern unsigned long profile_pc(struct pt_regs *regs);
#define profile_pc(regs) instruction_pointer(regs)
#endif
+long do_syscall_trace_enter(struct pt_regs *regs);
+void do_syscall_trace_leave(struct pt_regs *regs);
+
#define kernel_stack_pointer(regs) ((regs)->gpr[1])
static inline int is_syscall_success(struct pt_regs *regs)
{
diff --git a/arch/powerpc/include/asm/signal.h
b/arch/powerpc/include/asm/signal.h
index 0803ca8b9149..99e1c6de27bc 100644
--- a/arch/powerpc/include/asm/signal.h
+++ b/arch/powerpc/include/asm/signal.h
@@ -6,4 +6,7 @@
#include <uapi/asm/signal.h>
#include <uapi/asm/ptrace.h>
+struct pt_regs;
+void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags);
+
#endif /* _ASM_POWERPC_SIGNAL_H */
diff --git a/arch/powerpc/include/asm/switch_to.h
b/arch/powerpc/include/asm/switch_to.h
index 5b03d8a82409..476008bc3d08 100644
--- a/arch/powerpc/include/asm/switch_to.h
+++ b/arch/powerpc/include/asm/switch_to.h
@@ -5,6 +5,7 @@
#ifndef _ASM_POWERPC_SWITCH_TO_H
#define _ASM_POWERPC_SWITCH_TO_H
+#include <linux/sched.h>
#include <asm/reg.h>
struct thread_struct;
@@ -22,6 +23,10 @@ extern void switch_booke_debug_regs(struct debug_reg
*new_debug);
extern int emulate_altivec(struct pt_regs *);
+void restore_math(struct pt_regs *regs);
+
+void restore_tm_state(struct pt_regs *regs);
+
extern void flush_all_to_thread(struct task_struct *);
extern void giveup_all(struct task_struct *);
diff --git a/arch/powerpc/include/asm/time.h b/arch/powerpc/include/asm/time.h
index e0107495c4de..39ce95016a3a 100644
--- a/arch/powerpc/include/asm/time.h
+++ b/arch/powerpc/include/asm/time.h
@@ -194,5 +194,8 @@ DECLARE_PER_CPU(u64, decrementers_next_tb);
/* Convert timebase ticks to nanoseconds */
unsigned long long tb_to_ns(unsigned long long tb_ticks);
+/* SPLPAR */
+void accumulate_stolen_time(void);
+
#endif /* __KERNEL__ */
#endif /* __POWERPC_TIME_H */
diff --git a/arch/powerpc/kernel/Makefile b/arch/powerpc/kernel/Makefile
index 78a1b22d4fd8..5700231a8988 100644
--- a/arch/powerpc/kernel/Makefile
+++ b/arch/powerpc/kernel/Makefile
@@ -50,7 +50,8 @@ obj-y := cputable.o ptrace.o
syscalls.o \
of_platform.o prom_parse.o
obj-$(CONFIG_PPC64) += setup_64.o sys_ppc32.o \
signal_64.o ptrace32.o \
- paca.o nvram_64.o firmware.o note.o
+ paca.o nvram_64.o firmware.o note.o \
+ syscall_64.o
obj-$(CONFIG_VDSO32) += vdso32/
obj-$(CONFIG_PPC_WATCHDOG) += watchdog.o
obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
[snip]
diff --git a/arch/powerpc/kernel/signal.h b/arch/powerpc/kernel/signal.h
index 800433685888..d396efca4068 100644
--- a/arch/powerpc/kernel/signal.h
+++ b/arch/powerpc/kernel/signal.h
@@ -10,8 +10,6 @@
#ifndef _POWERPC_ARCH_SIGNAL_H
#define _POWERPC_ARCH_SIGNAL_H
-extern void do_notify_resume(struct pt_regs *regs, unsigned long thread_info_flags);
-
extern void __user *get_sigframe(struct ksignal *ksig, unsigned long sp,
size_t frame_size, int is_32);
diff --git a/arch/powerpc/kernel/syscall_64.c b/arch/powerpc/kernel/syscall_64.c
Could some part of it go in a syscall.c to be reused on PPC32 ?
new file mode 100644
index 000000000000..20f77cc19df8
--- /dev/null
+++ b/arch/powerpc/kernel/syscall_64.c
@@ -0,0 +1,213 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/err.h>
+#include <asm/asm-prototypes.h>
+#include <asm/book3s/64/kup-radix.h>
+#include <asm/cputime.h>
+#include <asm/hw_irq.h>
+#include <asm/kprobes.h>
+#include <asm/paca.h>
+#include <asm/ptrace.h>
+#include <asm/reg.h>
+#include <asm/signal.h>
+#include <asm/switch_to.h>
+#include <asm/syscall.h>
+#include <asm/time.h>
+#include <asm/unistd.h>
+
+extern void __noreturn tabort_syscall(unsigned long nip, unsigned long msr);
+
+typedef long (*syscall_fn)(long, long, long, long, long, long);
+
+/* Has to run notrace because it is entered "unreconciled" */
+notrace long system_call_exception(long r3, long r4, long r5, long r6, long
r7, long r8,
+ unsigned long r0, struct pt_regs *regs)
+{
+ unsigned long ti_flags;
+ syscall_fn f;
+
+ BUG_ON(!(regs->msr & MSR_PR));
+
+ if (IS_ENABLED(CONFIG_PPC_TRANSACTIONAL_MEM) &&
+ unlikely(regs->msr & MSR_TS_T))
+ tabort_syscall(regs->nip, regs->msr);
+
+ account_cpu_user_entry();
+
+#ifdef CONFIG_PPC_SPLPAR
+ if (IS_ENABLED(CONFIG_VIRT_CPU_ACCOUNTING_NATIVE) &&
+ firmware_has_feature(FW_FEATURE_SPLPAR)) {
+ struct lppaca *lp = local_paca->lppaca_ptr;
+
+ if (unlikely(local_paca->dtl_ridx != be64_to_cpu(lp->dtl_idx)))
+ accumulate_stolen_time();
+ }
+#endif
+
+ kuap_check_amr();
+
+ /*
+ * A syscall should always be called with interrupts enabled
+ * so we just unconditionally hard-enable here. When some kind
+ * of irq tracing is used, we additionally check that condition
+ * is correct
+ */
+ if (IS_ENABLED(CONFIG_PPC_IRQ_SOFT_MASK_DEBUG)) {
+ WARN_ON(irq_soft_mask_return() != IRQS_ENABLED);
+ WARN_ON(local_paca->irq_happened);
+ }
+ /*
+ * This is not required for the syscall exit path, but makes the
+ * stack frame look nicer. If this was initialised in the first stack
+ * frame, or if the unwinder was taught the first stack frame always
+ * returns to user with IRQS_ENABLED, this store could be avoided!
+ */
+ regs->softe = IRQS_ENABLED;
softe doesn't exist on PPC32. Can we do that through a helper ?
+
+ __hard_irq_enable();
This doesn't exist on PPC32. Should we define __hard_irq_enable() as
arch_local_irq_enable() on PPC32 ?
+
+ ti_flags = current_thread_info()->flags;
+ if (unlikely(ti_flags & _TIF_SYSCALL_DOTRACE)) {
+ /*
+ * We use the return value of do_syscall_trace_enter() as the
+ * syscall number. If the syscall was rejected for any reason
+ * do_syscall_trace_enter() returns an invalid syscall number
+ * and the test against NR_syscalls will fail and the return
+ * value to be used is in regs->gpr[3].
+ */
+ r0 = do_syscall_trace_enter(regs);
+ if (unlikely(r0 >= NR_syscalls))
+ return regs->gpr[3];
+ r3 = regs->gpr[3];
+ r4 = regs->gpr[4];
+ r5 = regs->gpr[5];
+ r6 = regs->gpr[6];
+ r7 = regs->gpr[7];
+ r8 = regs->gpr[8];
+
+ } else if (unlikely(r0 >= NR_syscalls)) {
+ return -ENOSYS;
+ }
+
+ /* May be faster to do array_index_nospec? */
+ barrier_nospec();
+
+ if (unlikely(ti_flags & _TIF_32BIT)) {
Use is_compat_task() instead ?
+ f = (void *)compat_sys_call_table[r0];
+
+ r3 &= 0x00000000ffffffffULL;
+ r4 &= 0x00000000ffffffffULL;
+ r5 &= 0x00000000ffffffffULL;
+ r6 &= 0x00000000ffffffffULL;
+ r7 &= 0x00000000ffffffffULL;
+ r8 &= 0x00000000ffffffffULL;
+
+ } else {
+ f = (void *)sys_call_table[r0];
+ }
+
+ return f(r3, r4, r5, r6, r7, r8);
+}
+
+/*
+ * This should be called after a syscall returns, with r3 the return value
+ * from the syscall. If this function returns non-zero, the system call
+ * exit assembly should additionally load all GPR registers and CTR and XER
+ * from the interrupt frame.
+ *
+ * The function graph tracer can not trace the return side of this function,
+ * because RI=0 and soft mask state is "unreconciled", so it is marked notrace.
+ */
+notrace unsigned long syscall_exit_prepare(unsigned long r3,
+ struct pt_regs *regs)
+{
+ unsigned long *ti_flagsp = ¤t_thread_info()->flags;
+ unsigned long ti_flags;
+ unsigned long ret = 0;
+
+ regs->result = r3;
+
+ /* Check whether the syscall is issued inside a restartable sequence */
+ rseq_syscall(regs);
+
+ ti_flags = *ti_flagsp;
+
+ if (unlikely(r3 >= (unsigned long)-MAX_ERRNO)) {
+ if (likely(!(ti_flags & (_TIF_NOERROR | _TIF_RESTOREALL)))) {
+ r3 = -r3;
+ regs->ccr |= 0x10000000; /* Set SO bit in CR */
+ }
+ }
+
+ if (unlikely(ti_flags & _TIF_PERSYSCALL_MASK)) {
+ if (ti_flags & _TIF_RESTOREALL)
+ ret = _TIF_RESTOREALL;
+ else
+ regs->gpr[3] = r3;
+ clear_bits(_TIF_PERSYSCALL_MASK, ti_flagsp);
+ } else {
+ regs->gpr[3] = r3;
+ }
+
+ if (unlikely(ti_flags & _TIF_SYSCALL_DOTRACE)) {
+ do_syscall_trace_leave(regs);
+ ret |= _TIF_RESTOREALL;
+ }
+
+again:
+ local_irq_disable();
+ ti_flags = READ_ONCE(*ti_flagsp);
+ while (unlikely(ti_flags & _TIF_USER_WORK_MASK)) {
+ local_irq_enable();
+ if (ti_flags & _TIF_NEED_RESCHED) {
+ schedule();
+ } else {
+ /*
+ * SIGPENDING must restore signal handler function
+ * argument GPRs, and some non-volatiles (e.g., r1).
+ * Restore all for now. This could be made lighter.
+ */
+ if (ti_flags & _TIF_SIGPENDING)
+ ret |= _TIF_RESTOREALL;
+ do_notify_resume(regs, ti_flags);
+ }
+ local_irq_disable();
+ ti_flags = READ_ONCE(*ti_flagsp);
+ }
+
+ if (IS_ENABLED(CONFIG_PPC_BOOK3S) && IS_ENABLED(CONFIG_PPC_FPU)) {
+ unsigned long mathflags = MSR_FP;
+
+ if (IS_ENABLED(CONFIG_ALTIVEC))
+ mathflags |= MSR_VEC;
+
+ if ((regs->msr & mathflags) != mathflags)
+ restore_math(regs);
+ }
+
+ /* This must be done with RI=1 because tracing may touch vmaps */
+ trace_hardirqs_on();
+
+ /* This pattern matches prep_irq_for_idle */
+ __hard_EE_RI_disable();
+ if (unlikely(lazy_irq_pending())) {
+ __hard_RI_enable();
+ trace_hardirqs_off();
+ local_paca->irq_happened |= PACA_IRQ_HARD_DIS;
+ local_irq_enable();
+ /* Took an interrupt which may have more exit work to do. */
+ goto again;
+ }
+ local_paca->irq_happened = 0;
+ irq_soft_mask_set(IRQS_ENABLED);
+
+#ifdef CONFIG_PPC_TRANSACTIONAL_MEM
+ local_paca->tm_scratch = regs->msr;
+#endif
+
+ kuap_check_amr();
+
+ account_cpu_user_exit();
+
+ return ret;
+}
diff --git a/arch/powerpc/kernel/systbl.S b/arch/powerpc/kernel/systbl.S
index 5b905a2f4e4d..d34276f3c495 100644
--- a/arch/powerpc/kernel/systbl.S
+++ b/arch/powerpc/kernel/systbl.S
@@ -16,25 +16,22 @@
#ifdef CONFIG_PPC64
.p2align 3
+#define __SYSCALL(nr, entry) .8byte entry
+#else
+#define __SYSCALL(nr, entry) .long entry
#endif
.globl sys_call_table
sys_call_table:
#ifdef CONFIG_PPC64
-#define __SYSCALL(nr, entry) .8byte DOTSYM(entry)
#include <asm/syscall_table_64.h>
-#undef __SYSCALL
#else
-#define __SYSCALL(nr, entry) .long entry
#include <asm/syscall_table_32.h>
-#undef __SYSCALL
#endif
#ifdef CONFIG_COMPAT
.globl compat_sys_call_table
compat_sys_call_table:
#define compat_sys_sigsuspend sys_sigsuspend
-#define __SYSCALL(nr, entry) .8byte DOTSYM(entry)
#include <asm/syscall_table_c32.h>
-#undef __SYSCALL
#endif
Christophe
