On 02/23/2015 04:35 PM, [email protected] wrote: > From: Jamie Garside <[email protected]> > > This patch fixes two bugs in the Microblaze syscall trap handler when an > invalid > syscall ID is used. > > First, the range check on line 351 only checks for syscall IDs greater than > __NR_syscalls. A negative syscall ID (either passed to `syscall()` or as > returned > by `do_syscall_trace_enter()` on error) will still satisfy this test and cause > the Linux kernel to access an invalid memory location and cause a kernel oops. > This has been fixed by also checking for r12 < 0. > > Secondly, the current error recovery at line 378 returns using the wrong > register > (r15 instead of r14) and does not restore the previous stack state. This has > been > fixed by invoking `ret_from_trap` on error, setting r3 to `-ENOSYS`, similar > to > what would happen when calling a valid syscall. > > Signed-off-by: Jamie Garside <[email protected]> > --- > arch/microblaze/kernel/entry.S | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/arch/microblaze/kernel/entry.S b/arch/microblaze/kernel/entry.S > index 0536bc0..101f13c 100644 > --- a/arch/microblaze/kernel/entry.S > +++ b/arch/microblaze/kernel/entry.S > @@ -348,8 +348,9 @@ C_ENTRY(_user_exception): > * The LP register should point to the location where the called function > * should return. [note that MAKE_SYS_CALL uses label 1] */ > /* See if the system call number is valid */ > + blti r12, 5f > addi r11, r12, -__NR_syscalls; > - bgei r11,5f; > + bgei r11, 5f; > /* Figure out which function to use for this system call. */ > /* Note Microblaze barrel shift is optional, so don't rely on it */ > add r12, r12, r12; /* convert num -> ptr */ > @@ -375,7 +376,7 @@ C_ENTRY(_user_exception): > > /* The syscall number is invalid, return an error. */ > 5: > - rtsd r15, 8; /* looks like a normal subroutine return */ > + braid ret_from_trap > addi r3, r0, -ENOSYS; > > /* Entry point used to return from a syscall/trap */ >
Looks reasonable and I have also tested it. I have fixed subject, coding style and I have create one more patch to fix that coding style issue. The patches should be in linux-next. Thanks, Michal -- Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91 w: www.monstr.eu p: +42-0-721842854 Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/ Maintainer of Linux kernel - Xilinx Zynq ARM architecture Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform
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