Messages in this thread Patch in this message | | | Date | Mon, 28 Oct 2019 17:34:21 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v4 13/16] arm/ftrace: Use __patch_text_real() |
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On Mon, Oct 28, 2019 at 04:25:26PM +0000, Will Deacon wrote: > Hi Peter, > > On Fri, Oct 18, 2019 at 09:35:38AM +0200, Peter Zijlstra wrote: > > Instead of flipping text protection, use the patch_text infrastructure > > that uses a fixmap alias where required. > > > > This removes the last user of set_all_modules_text_*(). > > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > Cc: ard.biesheuvel@linaro.org > > Cc: rabin@rab.in > > Cc: Mark Rutland <mark.rutland@arm.com> > > Cc: Will Deacon <will@kernel.org> > > Cc: james.morse@arm.com > > --- > > arch/arm/kernel/ftrace.c | 16 ++++++++-------- > > 1 file changed, 8 insertions(+), 8 deletions(-) > > > > --- a/arch/arm/kernel/ftrace.c > > +++ b/arch/arm/kernel/ftrace.c > > @@ -22,6 +22,7 @@ > > #include <asm/ftrace.h> > > #include <asm/insn.h> > > #include <asm/set_memory.h> > > +#include <asm/patch.h> > > > > #ifdef CONFIG_THUMB2_KERNEL > > #define NOP 0xf85deb04 /* pop.w {lr} */ > > @@ -31,13 +32,15 @@ > > > > #ifdef CONFIG_DYNAMIC_FTRACE > > > > +static int patch_text_remap = 0; > > + > > static int __ftrace_modify_code(void *data) > > { > > int *command = data; > > > > - set_kernel_text_rw(); > > + patch_text_remap++; > > ftrace_modify_all_code(*command); > > - set_kernel_text_ro(); > > + patch_text_remap--; > > > > return 0; > > } > > @@ -59,13 +62,13 @@ static unsigned long adjust_address(stru > > > > int ftrace_arch_code_modify_prepare(void) > > { > > - set_all_modules_text_rw(); > > + patch_text_remap++; > > return 0; > > } > > > > int ftrace_arch_code_modify_post_process(void) > > { > > - set_all_modules_text_ro(); > > + patch_text_remap--; > > /* Make sure any TLB misses during machine stop are cleared. */ > > flush_tlb_all(); > > return 0; > > @@ -97,10 +100,7 @@ static int ftrace_modify_code(unsigned l > > return -EINVAL; > > } > > > > - if (probe_kernel_write((void *)pc, &new, MCOUNT_INSN_SIZE)) > > - return -EPERM; > > - > > - flush_icache_range(pc, pc + MCOUNT_INSN_SIZE); > > + __patch_text_real((void *)pc, new, patch_text_remap); > > Why can't you just pass 'true' for patch_text_remap? AFAICT, the only > time you want to pass false is during early boot when the text is > assumedly still writable without the fixmap.
Ah, it will also become true for module loading once we rework where we flip the module text RO,X. See this patch:
https://lkml.kernel.org/r/20191018074634.858645375@infradead.org
But for that to land, there's still a few other issues to fix (KLP).
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