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Re: [Qemu-devel] [PATCH 2/2] linux-user: Fix indirect syscall handling f
From: |
An-Cheng Huang |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] linux-user: Fix indirect syscall handling for MIPS |
Date: |
Fri, 5 Aug 2011 10:57:37 -0700 |
User-agent: |
Mutt/1.5.20 (2009-06-14) |
On Fri, Aug 05, 2011 at 10:27:21AM +0100, Peter Maydell wrote:
> On 5 August 2011 01:05, An-Cheng Huang <address@hidden> wrote:
> > Ok the following patch changes the number of arguments for sys_syscall
> > to 8 in mips_syscall_args and also skips the do_syscall() call if any
> > of the get_user() calls fails. Do you think combining these makes sense
> > or should they be two separate patches? Thanks.
>
> The code in this patch looks good, but yes, I think they should
> be two separate patches.
And the second patch:
This patch verifies that MIPS syscall arguments are successfully taken from the
stack before proceeding to do_syscall().
Signed-off-by: An-Cheng Huang <address@hidden>
---
linux-user/main.c | 22 +++++++++++++++++-----
1 files changed, 17 insertions(+), 5 deletions(-)
diff --git a/linux-user/main.c b/linux-user/main.c
index 9e67b24..701d96e 100644
--- a/linux-user/main.c
+++ b/linux-user/main.c
@@ -2090,11 +2090,22 @@ void cpu_loop(CPUMIPSState *env)
sp_reg = env->active_tc.gpr[29];
switch (nb_args) {
/* these arguments are taken from the stack */
- /* FIXME - what to do if get_user() fails? */
- case 8: get_user_ual(arg8, sp_reg + 28);
- case 7: get_user_ual(arg7, sp_reg + 24);
- case 6: get_user_ual(arg6, sp_reg + 20);
- case 5: get_user_ual(arg5, sp_reg + 16);
+ case 8:
+ if ((ret = get_user_ual(arg8, sp_reg + 28)) != 0) {
+ goto done_syscall;
+ }
+ case 7:
+ if ((ret = get_user_ual(arg7, sp_reg + 24)) != 0) {
+ goto done_syscall;
+ }
+ case 6:
+ if ((ret = get_user_ual(arg6, sp_reg + 20)) != 0) {
+ goto done_syscall;
+ }
+ case 5:
+ if ((ret = get_user_ual(arg5, sp_reg + 16)) != 0) {
+ goto done_syscall;
+ }
default:
break;
}
@@ -2105,6 +2116,7 @@ void cpu_loop(CPUMIPSState *env)
env->active_tc.gpr[7],
arg5, arg6, arg7, arg8);
}
+done_syscall:
if (ret == -TARGET_QEMU_ESIGRETURN) {
/* Returning from a successful sigreturn syscall.
Avoid clobbering register state. */