From: Rohan McLure <rmclure@linux.ibm.com>
To: linuxppc-dev@lists.ozlabs.org
Cc: Rohan McLure <rmclure@linux.ibm.com>,
Andrew Donnellan <ajd@linux.ibm.com>
Subject: [PATCH v6 21/25] powerpc: Provide syscall wrapper
Date: Wed, 21 Sep 2022 16:56:01 +1000 [thread overview]
Message-ID: <20220921065605.1051927-22-rmclure@linux.ibm.com> (raw)
In-Reply-To: <20220921065605.1051927-1-rmclure@linux.ibm.com>
Implement syscall wrapper as per s390, x86, arm64. When enabled
cause handlers to accept parameters from a stack frame rather than
from user scratch register state. This allows for user registers to be
safely cleared in order to reduce caller influence on speculation
within syscall routine. The wrapper is a macro that emits syscall
handler symbols that call into the target handler, obtaining its
parameters from a struct pt_regs on the stack.
As registers are already saved to the stack prior to calling
system_call_exception, it appears that this function is executed more
efficiently with the new stack-pointer convention than with parameters
passed by registers, avoiding the allocation of a stack frame for this
method. On a 32-bit system, we see >20% performance increases on the
null_syscall microbenchmark, and on a Power 8 the performance gains
amortise the cost of clearing and restoring registers which is
implemented at the end of this series, seeing final result of ~5.6%
performance improvement on null_syscall.
Syscalls are wrapped in this fashion on all platforms except for the
Cell processor as this commit does not provide SPU support. This can be
quickly fixed in a successive patch, but requires spu_sys_callback to
allocate a pt_regs structure to satisfy the wrapped calling convention.
Co-developed-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Andrew Donnellan <ajd@linux.ibm.com>
Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
---
V2: Generate prototypes for symbols produced by the wrapper.
V3: Rebased to remove conflict with 1547db7d1f44
("powerpc: Move system_call_exception() to syscall.c"). Also remove copy
from gpr3 save slot on stackframe to orig_r3's slot. Fix whitespace with
preprocessor defines in system_call_exception.
V5: Move systbl.c syscall wrapper support to this patch. Swap
calling convention for system_call_exception to be (®s, r0)
V6: Change calling convention for system_call_exception in another
patch.
---
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/syscall.h | 4 +
arch/powerpc/include/asm/syscall_wrapper.h | 84 ++++++++++++++++++++
arch/powerpc/include/asm/syscalls.h | 30 ++++++-
arch/powerpc/kernel/syscall.c | 7 +-
arch/powerpc/kernel/systbl.c | 7 ++
arch/powerpc/kernel/vdso.c | 2 +
7 files changed, 132 insertions(+), 3 deletions(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 4c466acdc70d..ef6c83e79c9b 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -137,6 +137,7 @@ config PPC
select ARCH_HAS_STRICT_KERNEL_RWX if (PPC_BOOK3S || PPC_8xx || 40x) && !HIBERNATION
select ARCH_HAS_STRICT_KERNEL_RWX if FSL_BOOKE && !HIBERNATION && !RANDOMIZE_BASE
select ARCH_HAS_STRICT_MODULE_RWX if ARCH_HAS_STRICT_KERNEL_RWX
+ select ARCH_HAS_SYSCALL_WRAPPER if !SPU_BASE
select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
select ARCH_HAS_UACCESS_FLUSHCACHE
select ARCH_HAS_UBSAN_SANITIZE_ALL
diff --git a/arch/powerpc/include/asm/syscall.h b/arch/powerpc/include/asm/syscall.h
index d2a8dfd5de33..3dd36c5e334a 100644
--- a/arch/powerpc/include/asm/syscall.h
+++ b/arch/powerpc/include/asm/syscall.h
@@ -14,8 +14,12 @@
#include <linux/sched.h>
#include <linux/thread_info.h>
+#ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
+typedef long (*syscall_fn)(const struct pt_regs *);
+#else
typedef long (*syscall_fn)(unsigned long, unsigned long, unsigned long,
unsigned long, unsigned long, unsigned long);
+#endif
/* ftrace syscalls requires exporting the sys_call_table */
extern const syscall_fn sys_call_table[];
diff --git a/arch/powerpc/include/asm/syscall_wrapper.h b/arch/powerpc/include/asm/syscall_wrapper.h
new file mode 100644
index 000000000000..91bcfa40f740
--- /dev/null
+++ b/arch/powerpc/include/asm/syscall_wrapper.h
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * syscall_wrapper.h - powerpc specific wrappers to syscall definitions
+ *
+ * Based on arch/{x86,arm64}/include/asm/syscall_wrapper.h
+ */
+
+#ifndef __ASM_SYSCALL_WRAPPER_H
+#define __ASM_SYSCALL_WRAPPER_H
+
+struct pt_regs;
+
+#define SC_POWERPC_REGS_TO_ARGS(x, ...) \
+ __MAP(x,__SC_ARGS \
+ ,,regs->gpr[3],,regs->gpr[4],,regs->gpr[5] \
+ ,,regs->gpr[6],,regs->gpr[7],,regs->gpr[8])
+
+#ifdef CONFIG_COMPAT
+
+#define COMPAT_SYSCALL_DEFINEx(x, name, ...) \
+ long __powerpc_compat_sys##name(const struct pt_regs *regs); \
+ ALLOW_ERROR_INJECTION(__powerpc_compat_sys##name, ERRNO); \
+ static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
+ static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \
+ long __powerpc_compat_sys##name(const struct pt_regs *regs) \
+ { \
+ return __se_compat_sys##name(SC_POWERPC_REGS_TO_ARGS(x,__VA_ARGS__)); \
+ } \
+ static long __se_compat_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
+ { \
+ return __do_compat_sys##name(__MAP(x,__SC_DELOUSE,__VA_ARGS__)); \
+ } \
+ static inline long __do_compat_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
+
+#define COMPAT_SYSCALL_DEFINE0(sname) \
+ long __powerpc_compat_sys_##sname(const struct pt_regs *__unused); \
+ ALLOW_ERROR_INJECTION(__powerpc_compat_sys_##sname, ERRNO); \
+ long __powerpc_compat_sys_##sname(const struct pt_regs *__unused)
+
+#define COND_SYSCALL_COMPAT(name) \
+ long __powerpc_compat_sys_##name(const struct pt_regs *regs); \
+ long __weak __powerpc_compat_sys_##name(const struct pt_regs *regs) \
+ { \
+ return sys_ni_syscall(); \
+ }
+#define COMPAT_SYS_NI(name) \
+ SYSCALL_ALIAS(__powerpc_compat_sys_##name, sys_ni_posix_timers);
+
+#endif /* CONFIG_COMPAT */
+
+#define __SYSCALL_DEFINEx(x, name, ...) \
+ long __powerpc_sys##name(const struct pt_regs *regs); \
+ ALLOW_ERROR_INJECTION(__powerpc_sys##name, ERRNO); \
+ static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \
+ static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \
+ long __powerpc_sys##name(const struct pt_regs *regs) \
+ { \
+ return __se_sys##name(SC_POWERPC_REGS_TO_ARGS(x,__VA_ARGS__)); \
+ } \
+ static long __se_sys##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \
+ { \
+ long ret = __do_sys##name(__MAP(x,__SC_CAST,__VA_ARGS__)); \
+ __MAP(x,__SC_TEST,__VA_ARGS__); \
+ __PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \
+ return ret; \
+ } \
+ static inline long __do_sys##name(__MAP(x,__SC_DECL,__VA_ARGS__))
+
+#define SYSCALL_DEFINE0(sname) \
+ SYSCALL_METADATA(_##sname, 0); \
+ long __powerpc_sys_##sname(const struct pt_regs *__unused); \
+ ALLOW_ERROR_INJECTION(__powerpc_sys_##sname, ERRNO); \
+ long __powerpc_sys_##sname(const struct pt_regs *__unused)
+
+#define COND_SYSCALL(name) \
+ long __powerpc_sys_##name(const struct pt_regs *regs); \
+ long __weak __powerpc_sys_##name(const struct pt_regs *regs) \
+ { \
+ return sys_ni_syscall(); \
+ }
+
+#define SYS_NI(name) SYSCALL_ALIAS(__powerpc_sys_##name, sys_ni_posix_timers);
+
+#endif /* __ASM_SYSCALL_WRAPPER_H */
diff --git a/arch/powerpc/include/asm/syscalls.h b/arch/powerpc/include/asm/syscalls.h
index cc87168d6ecb..1ecdf6c071f6 100644
--- a/arch/powerpc/include/asm/syscalls.h
+++ b/arch/powerpc/include/asm/syscalls.h
@@ -15,6 +15,12 @@
#include <asm/unistd.h>
#include <asm/ucontext.h>
+#ifndef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
+long sys_ni_syscall(void);
+#else
+long sys_ni_syscall(const struct pt_regs *regs);
+#endif
+
struct rtas_args;
/*
@@ -29,12 +35,12 @@ struct rtas_args;
#define merge_64(high, low) ((u64)high << 32) | low
#endif
-long sys_ni_syscall(void);
-
/*
* PowerPC architecture-specific syscalls
*/
+#ifndef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
+
long sys_rtas(struct rtas_args __user *uargs);
#ifdef CONFIG_PPC64
@@ -114,5 +120,25 @@ long sys_ppc_fadvise64_64(int fd, int advice,
u32 len_high, u32 len_low);
#endif
+#else
+
+#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, native)
+#define __SYSCALL(nr, entry) \
+ long __powerpc_##entry(const struct pt_regs *regs);
+
+#ifdef CONFIG_PPC64
+#include <asm/syscall_table_64.h>
+#else
+#include <asm/syscall_table_32.h>
+#endif /* CONFIG_PPC64 */
+
+#ifdef CONFIG_COMPAT
+#undef __SYSCALL_WITH_COMPAT
+#define __SYSCALL_WITH_COMPAT(nr, native, compat) __SYSCALL(nr, compat)
+#include <asm/syscall_table_32.h>
+#endif /* CONFIG_COMPAT */
+
+#endif /* CONFIG_ARCH_HAS_SYSCALL_WRAPPER */
+
#endif /* __KERNEL__ */
#endif /* __ASM_POWERPC_SYSCALLS_H */
diff --git a/arch/powerpc/kernel/syscall.c b/arch/powerpc/kernel/syscall.c
index 0e9ba3efee94..38c499afc689 100644
--- a/arch/powerpc/kernel/syscall.c
+++ b/arch/powerpc/kernel/syscall.c
@@ -153,7 +153,12 @@ notrace long system_call_exception(struct pt_regs *regs, unsigned long r0)
f = (void *)sys_call_table[r0];
}
- ret = f(r3, r4, r5, r6, r7, r8);
+#ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
+ ret = f(regs);
+#else
+ ret = f(regs->gpr[3], regs->gpr[4], regs->gpr[5],
+ regs->gpr[6], regs->gpr[7], regs->gpr[8]);
+#endif
/*
* Ultimately, this value will get limited by KSTACK_OFFSET_MAX(),
diff --git a/arch/powerpc/kernel/systbl.c b/arch/powerpc/kernel/systbl.c
index d64dfafc2e5e..9d7c5a596171 100644
--- a/arch/powerpc/kernel/systbl.c
+++ b/arch/powerpc/kernel/systbl.c
@@ -15,13 +15,20 @@
#include <asm/unistd.h>
#include <asm/syscalls.h>
+#undef __SYSCALL_WITH_COMPAT
#define __SYSCALL_WITH_COMPAT(nr, entry, compat) __SYSCALL(nr, entry)
+#undef __SYSCALL
+#ifdef CONFIG_ARCH_HAS_SYSCALL_WRAPPER
+#define __SYSCALL(nr, entry) [nr] = __powerpc_##entry,
+#define __powerpc_sys_ni_syscall sys_ni_syscall
+#else
/*
* Coerce syscall handlers with arbitrary parameters to common type
* requires cast to void* to avoid -Wcast-function-type.
*/
#define __SYSCALL(nr, entry) [nr] = (void *) entry,
+#endif
const syscall_fn sys_call_table[] = {
#ifdef CONFIG_PPC64
diff --git a/arch/powerpc/kernel/vdso.c b/arch/powerpc/kernel/vdso.c
index fcca06d200d3..e1f36fd61db3 100644
--- a/arch/powerpc/kernel/vdso.c
+++ b/arch/powerpc/kernel/vdso.c
@@ -39,6 +39,8 @@
extern char vdso32_start, vdso32_end;
extern char vdso64_start, vdso64_end;
+long sys_ni_syscall(void);
+
/*
* The vdso data page (aka. systemcfg for old ppc64 fans) is here.
* Once the early boot kernel code no longer needs to muck around
--
2.34.1
next prev parent reply other threads:[~2022-09-21 7:11 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-21 6:55 [PATCH v6 00/25] powerpc: Syscall wrapper and register clearing Rohan McLure
2022-09-21 6:55 ` [PATCH v6 01/25] powerpc: Remove asmlinkage from syscall handler definitions Rohan McLure
2022-09-21 6:55 ` [PATCH v6 02/25] powerpc: Save caller r3 prior to system_call_exception Rohan McLure
2022-09-21 6:55 ` [PATCH v6 03/25] powerpc: Add ZEROIZE_GPRS macros for register clears Rohan McLure
2022-09-21 6:55 ` [PATCH v6 04/25] powerpc/64s: Use {ZEROIZE,SAVE,REST}_GPRS macros in sc, scv 0 handlers Rohan McLure
2022-09-21 6:55 ` [PATCH v6 05/25] powerpc/32: Clarify interrupt restores with REST_GPR macro in entry_32.S Rohan McLure
2022-09-21 6:55 ` [PATCH v6 06/25] powerpc/64e: Clarify register saves and clears with {SAVE,ZEROIZE}_GPRS Rohan McLure
2022-09-21 6:55 ` [PATCH v6 07/25] powerpc/64s: Fix comment on interrupt handler prologue Rohan McLure
2022-09-21 6:55 ` [PATCH v6 08/25] powerpc: Fix fallocate and fadvise64_64 compat parameter combination Rohan McLure
2022-09-21 6:55 ` [PATCH v6 09/25] asm-generic: compat: Support BE for long long args in 32-bit ABIs Rohan McLure
2022-10-31 13:23 ` [PATCH] asm-generic: compat: fix compat_arg_u64 and compat_arg_u64_dual Andreas Schwab
2022-11-01 12:25 ` Michael Ellerman
2022-11-03 8:20 ` Christophe Leroy
2022-11-03 8:48 ` Arnd Bergmann
2022-09-21 6:55 ` [PATCH v6 10/25] powerpc: Use generic fallocate compatibility syscall Rohan McLure
2022-09-21 6:55 ` [PATCH v6 11/25] powerpc/32: Remove powerpc select specialisation Rohan McLure
2022-09-21 6:55 ` [PATCH v6 12/25] powerpc: Remove direct call to personality syscall handler Rohan McLure
2022-09-21 6:55 ` [PATCH v6 13/25] powerpc: Remove direct call to mmap2 syscall handlers Rohan McLure
2022-09-28 12:15 ` Michael Ellerman
2022-09-28 13:00 ` Arnd Bergmann
2022-09-30 13:19 ` Michael Ellerman
2022-09-30 14:09 ` Arnd Bergmann
2022-09-21 6:55 ` [PATCH v6 14/25] powerpc: Provide do_ppc64_personality helper Rohan McLure
2022-09-21 6:55 ` [PATCH v6 15/25] powerpc: Adopt SYSCALL_DEFINE for arch-specific syscall handlers Rohan McLure
2022-09-21 6:55 ` [PATCH v6 16/25] powerpc: Include all arch-specific syscall prototypes Rohan McLure
2022-09-21 6:55 ` [PATCH v6 17/25] powerpc: Enable compile-time check for syscall handlers Rohan McLure
2022-09-21 6:55 ` [PATCH v6 18/25] powerpc: Use common syscall handler type Rohan McLure
2022-09-21 6:55 ` [PATCH v6 19/25] powerpc: Remove high-order word clearing on compat syscall entry Rohan McLure
2022-09-23 7:40 ` Nicholas Piggin
2022-09-28 11:56 ` Michael Ellerman
2022-09-21 6:56 ` [PATCH v6 20/25] powerpc: Change system_call_exception calling convention Rohan McLure
2022-09-23 7:43 ` Nicholas Piggin
2022-09-21 6:56 ` Rohan McLure [this message]
2022-09-23 7:50 ` [PATCH v6 21/25] powerpc: Provide syscall wrapper Nicholas Piggin
2022-10-30 15:34 ` Andreas Schwab
2022-10-30 15:50 ` Andreas Schwab
2022-10-30 19:43 ` Arnd Bergmann
2022-10-30 20:05 ` Andreas Schwab
2022-10-31 3:09 ` Michael Ellerman
2022-10-31 14:47 ` [PATCH] powerpc/32: fix syscall wrappers with 64-bit arguments Andreas Schwab
2022-10-31 19:37 ` Arnd Bergmann
2022-11-01 12:25 ` Michael Ellerman
2022-09-21 6:56 ` [PATCH v6 22/25] powerpc/64s: Clear user GPRs in syscall interrupt entry Rohan McLure
2022-09-23 8:02 ` Nicholas Piggin
2022-10-31 23:22 ` Rohan McLure
2022-09-21 6:56 ` [PATCH v6 23/25] powerpc/64: Add INTERRUPT_SANITIZE_REGISTERS Kconfig Rohan McLure
2022-09-21 6:56 ` [PATCH v6 24/25] powerpc/64s: Clear gprs on interrupt routine entry in Book3S Rohan McLure
2022-09-21 6:56 ` [PATCH v6 25/25] powerpc/64e: Clear gprs on interrupt routine entry on Book3E Rohan McLure
2022-10-04 13:24 ` [PATCH v6 00/25] powerpc: Syscall wrapper and register clearing Michael Ellerman
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