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authorSuresh Siddha <suresh.b.siddha@intel.com>2009-10-28 22:46:57 -0400
committerIngo Molnar <mingo@elte.hu>2009-11-02 11:16:36 -0500
commit55ca3cc1746335bb6ef1d3894ddb6d0c729b3518 (patch)
tree1678b567a1d4ebb92c51abc0234334023879c749 /arch/x86/kernel/ftrace.c
parent502f660466ba7a66711ffdf414b1f7f1131dcbf7 (diff)
x86_64, ftrace: Make ftrace use kernel identity mapping to modify code
On x86_64, kernel text mappings are mapped read-only with CONFIG_DEBUG_RODATA. So use the kernel identity mapping instead of the kernel text mapping to modify the kernel text. Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Tested-by: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <20091029024821.080941108@sbs-t61.sc.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/ftrace.c')
-rw-r--r--arch/x86/kernel/ftrace.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
index 9dbb527e1652..944e9820b4b5 100644
--- a/arch/x86/kernel/ftrace.c
+++ b/arch/x86/kernel/ftrace.c
@@ -187,9 +187,26 @@ static void wait_for_nmi(void)
187 nmi_wait_count++; 187 nmi_wait_count++;
188} 188}
189 189
190static inline int
191within(unsigned long addr, unsigned long start, unsigned long end)
192{
193 return addr >= start && addr < end;
194}
195
190static int 196static int
191do_ftrace_mod_code(unsigned long ip, void *new_code) 197do_ftrace_mod_code(unsigned long ip, void *new_code)
192{ 198{
199 /*
200 * On x86_64, kernel text mappings are mapped read-only with
201 * CONFIG_DEBUG_RODATA. So we use the kernel identity mapping instead
202 * of the kernel text mapping to modify the kernel text.
203 *
204 * For 32bit kernels, these mappings are same and we can use
205 * kernel identity mapping to modify code.
206 */
207 if (within(ip, (unsigned long)_text, (unsigned long)_etext))
208 ip = (unsigned long)__va(__pa(ip));
209
193 mod_code_ip = (void *)ip; 210 mod_code_ip = (void *)ip;
194 mod_code_newcode = new_code; 211 mod_code_newcode = new_code;
195 212