Commit 55ca3cc1 authored by Suresh Siddha's avatar Suresh Siddha Committed by Ingo Molnar

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: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Acked-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Tested-by: default avatarSteven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20091029024821.080941108@sbs-t61.sc.intel.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 502f6604
......@@ -187,9 +187,26 @@ static void wait_for_nmi(void)
nmi_wait_count++;
}
static inline int
within(unsigned long addr, unsigned long start, unsigned long end)
{
return addr >= start && addr < end;
}
static int
do_ftrace_mod_code(unsigned long ip, void *new_code)
{
/*
* On x86_64, kernel text mappings are mapped read-only with
* CONFIG_DEBUG_RODATA. So we use the kernel identity mapping instead
* of the kernel text mapping to modify the kernel text.
*
* For 32bit kernels, these mappings are same and we can use
* kernel identity mapping to modify code.
*/
if (within(ip, (unsigned long)_text, (unsigned long)_etext))
ip = (unsigned long)__va(__pa(ip));
mod_code_ip = (void *)ip;
mod_code_newcode = new_code;
......
......@@ -279,8 +279,7 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
__pa((unsigned long)__end_rodata) >> PAGE_SHIFT))
pgprot_val(forbidden) |= _PAGE_RW;
#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA) && \
!defined(CONFIG_DYNAMIC_FTRACE)
#if defined(CONFIG_X86_64) && defined(CONFIG_DEBUG_RODATA)
/*
* Once the kernel maps the text as RO (kernel_set_to_readonly is set),
* kernel text mappings for the large page aligned text, rodata sections
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment