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um: Store syscall number after syscall_trace_enter()

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To support changing syscall numbers we have to store
it after syscall_trace_enter().

Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Richard Weinberger 2015-10-25 19:54:33 +01:00
parent 44011b897a
commit 1d80f0cda1
3 changed files with 11 additions and 13 deletions
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1
arch/um/include/shared/os.h
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@ -274,6 +274,7 @@ extern void initial_thread_cb_skas(void (*proc)(void *),
void *arg); void *arg);
extern void halt_skas(void); extern void halt_skas(void);
extern void reboot_skas(void); extern void reboot_skas(void);
extern int get_syscall(struct uml_pt_regs *regs);
/* irq.c */ /* irq.c */
extern int os_waiting_for_events(struct irq_fd *active_fds); extern int os_waiting_for_events(struct irq_fd *active_fds);

13
arch/um/kernel/skas/syscall.c
View file

@ -8,6 +8,7 @@
#include <kern_util.h> #include <kern_util.h>
#include <sysdep/ptrace.h> #include <sysdep/ptrace.h>
#include <sysdep/syscalls.h> #include <sysdep/syscalls.h>
#include <os.h>
extern int syscall_table_size; extern int syscall_table_size;
#define NR_SYSCALLS (syscall_table_size / sizeof(void *)) #define NR_SYSCALLS (syscall_table_size / sizeof(void *))
@ -23,16 +24,8 @@ void handle_syscall(struct uml_pt_regs *r)
goto out; goto out;
} }
/* syscall = get_syscall(r);
* This should go in the declaration of syscall, but when I do that,
* strace -f -c bash -c 'ls ; ls' breaks, sometimes not tracing
* children at all, sometimes hanging when bash doesn't see the first
* ls exit.
* The assembly looks functionally the same to me. This is
* gcc version 4.0.1 20050727 (Red Hat 4.0.1-5)
* in case it's a compiler bug.
*/
syscall = UPT_SYSCALL_NR(r);
if ((syscall >= NR_SYSCALLS) || (syscall < 0)) if ((syscall >= NR_SYSCALLS) || (syscall < 0))
result = -ENOSYS; result = -ENOSYS;
else result = EXECUTE_SYSCALL(syscall, regs); else result = EXECUTE_SYSCALL(syscall, regs);

10
arch/um/os-Linux/skas/process.c
View file

@ -137,9 +137,6 @@ static void handle_trap(int pid, struct uml_pt_regs *regs,
if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END)) if ((UPT_IP(regs) >= STUB_START) && (UPT_IP(regs) < STUB_END))
fatal_sigsegv(); fatal_sigsegv();
/* Mark this as a syscall */
UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
if (!local_using_sysemu) if (!local_using_sysemu)
{ {
err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET, err = ptrace(PTRACE_POKEUSER, pid, PT_SYSCALL_NR_OFFSET,
@ -174,6 +171,13 @@ static void handle_trap(int pid, struct uml_pt_regs *regs,
handle_syscall(regs); handle_syscall(regs);
} }
int get_syscall(struct uml_pt_regs *regs)
{
UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
return UPT_SYSCALL_NR(regs);
}
extern char __syscall_stub_start[]; extern char __syscall_stub_start[];
static int userspace_tramp(void *stack) static int userspace_tramp(void *stack)