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| author | Sven Schnelle <svens@linux.ibm.com> | 2021-06-30 13:50:55 +0200 |
|---|---|---|
| committer | Vasily Gorbik <gor@linux.ibm.com> | 2021-07-08 22:12:17 +0200 |
| commit | e3c7a8d7f44f4b36eb299563526ef8c5cb8011b0 (patch) | |
| tree | 52cfa082f382217276692a600044625c4c93768a /arch | |
| parent | fbf50f47ea99d07aec59859027352d4837e84ce1 (diff) | |
| download | lwn-e3c7a8d7f44f4b36eb299563526ef8c5cb8011b0.tar.gz lwn-e3c7a8d7f44f4b36eb299563526ef8c5cb8011b0.zip | |
s390: move restart of execve() syscall
On s390, execve might have to be restarted for PGSTE binaries
like kvm. In the past this was done via the PIF_SYSCALL_RESTART
bit. However, with the recent changes, syscalls are now restarted
differently. Now that execve() is the only call that might get
restarted via PIF_SYSCALL_RESTART, move the loop to do_syscall().
This also has the advantage that the restart is no longer visible
to userspace.
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/s390/include/asm/ptrace.h | 8 | ||||
| -rw-r--r-- | arch/s390/kernel/syscall.c | 27 |
2 files changed, 20 insertions, 15 deletions
diff --git a/arch/s390/include/asm/ptrace.h b/arch/s390/include/asm/ptrace.h index c7850d649373..808da21235ab 100644 --- a/arch/s390/include/asm/ptrace.h +++ b/arch/s390/include/asm/ptrace.h @@ -162,6 +162,14 @@ static inline int test_pt_regs_flag(struct pt_regs *regs, int flag) return !!(regs->flags & (1UL << flag)); } +static inline int test_and_clear_pt_regs_flag(struct pt_regs *regs, int flag) +{ + int ret = test_pt_regs_flag(regs, flag); + + clear_pt_regs_flag(regs, flag); + return ret; +} + /* * These are defined as per linux/ptrace.h, which see. */ diff --git a/arch/s390/kernel/syscall.c b/arch/s390/kernel/syscall.c index ec73d2c61e58..0322f00f84ac 100644 --- a/arch/s390/kernel/syscall.c +++ b/arch/s390/kernel/syscall.c @@ -134,13 +134,15 @@ static void do_syscall(struct pt_regs *regs) * work, the ptrace code sets PIF_SYSCALL_RET_SET, which is checked here * and if set, the syscall will be skipped. */ - if (!test_pt_regs_flag(regs, PIF_SYSCALL_RET_SET)) { - regs->gprs[2] = -ENOSYS; - if (likely(nr < NR_syscalls)) - regs->gprs[2] = current->thread.sys_call_table[nr](regs); - } else { - clear_pt_regs_flag(regs, PIF_SYSCALL_RET_SET); - } + if (unlikely(test_and_clear_pt_regs_flag(regs, PIF_SYSCALL_RET_SET))) + goto out; + regs->gprs[2] = -ENOSYS; + if (likely(nr >= NR_syscalls)) + goto out; + do { + regs->gprs[2] = current->thread.sys_call_table[nr](regs); + } while (test_and_clear_pt_regs_flag(regs, PIF_SYSCALL_RESTART)); +out: syscall_exit_to_user_mode_work(regs); } @@ -158,13 +160,8 @@ void noinstr __do_syscall(struct pt_regs *regs, int per_trap) if (per_trap) set_thread_flag(TIF_PER_TRAP); - for (;;) { - regs->flags = 0; - set_pt_regs_flag(regs, PIF_SYSCALL); - do_syscall(regs); - if (!test_pt_regs_flag(regs, PIF_SYSCALL_RESTART)) - break; - local_irq_enable(); - } + regs->flags = 0; + set_pt_regs_flag(regs, PIF_SYSCALL); + do_syscall(regs); exit_to_user_mode(); } |