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authorJamie Garside <jamie.garside@york.ac.uk>2015-02-23 15:35:35 +0000
committerMichal Simek <michal.simek@xilinx.com>2015-03-04 15:12:27 +0100
commitc2219eda547813c0c50dba90d9e989ae36cc3ab8 (patch)
tree79e5d3d4810030c686e84403f274bfd1c952afa5 /arch
parent074fa7e76cfff4cd1a60753ee4596510f1b87183 (diff)
microblaze: Fix syscall error recovery for invalid syscall IDs
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 <jamie.garside@york.ac.uk> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/microblaze/kernel/entry.S3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/microblaze/kernel/entry.S b/arch/microblaze/kernel/entry.S
index 5dcb0e1a41c4..ef548510b951 100644
--- a/arch/microblaze/kernel/entry.S
+++ b/arch/microblaze/kernel/entry.S
@@ -348,6 +348,7 @@ 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;
/* Figure out which function to use for this system call. */
@@ -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 */