diff options
| author | H. Peter Anvin <hpa@linux.intel.com> | 2013-08-31 02:29:29 +0200 |
|---|---|---|
| committer | Steven Rostedt <rostedt@goodmis.org> | 2013-09-05 15:31:32 +0200 |
| commit | af058ab04d3d11383e5159132fc78a3700be3af5 (patch) | |
| tree | de93ea2d0b82f679cafb788444ed91e127abcf48 /arch/x86 | |
| parent | ftrace: Fix a slight race in modifying what function callback gets traced (diff) | |
| download | linux-af058ab04d3d11383e5159132fc78a3700be3af5.tar.xz linux-af058ab04d3d11383e5159132fc78a3700be3af5.zip | |
x86-32, ftrace: Fix static ftrace when early microcode is enabled
Early microcode loading runs C code before paging is enabled on 32
bits. Since ftrace puts a hook into every function, that hook needs
to be safe to execute in the pre-paging environment. This is
currently true for dynamic ftrace but not for static ftrace.
Static ftrace is obsolescent and assumed to not be
performance-critical, so we can simply test that the stack pointer
falls within the valid range of kernel addresses.
Reported-by: Jan Kiszka <jan.kiszka@siemens.com>
Tested-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/kernel/entry_32.S | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S index 2cfbc3a3a2dd..f0dcb0ceb6a2 100644 --- a/arch/x86/kernel/entry_32.S +++ b/arch/x86/kernel/entry_32.S @@ -1176,6 +1176,9 @@ ftrace_restore_flags: #else /* ! CONFIG_DYNAMIC_FTRACE */ ENTRY(mcount) + cmpl $__PAGE_OFFSET, %esp + jb ftrace_stub /* Paging not enabled yet? */ + cmpl $0, function_trace_stop jne ftrace_stub |