| Message ID | 87iks3wt2t.ffs@tglx (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | modpost: Add .irqentry.text to OTHER_SECTIONS | expand |
On Sun, Dec 1, 2024 at 8:17 PM Thomas Gleixner <tglx@linutronix.de> wrote: > > The compiler can fully inline the actual handler function of an interrupt > entry into the .irqentry.text entry point. If such a function contains an > access which has an exception table entry, modpost complains about a > section mismatch: > > WARNING: vmlinux.o(__ex_table+0x447c): Section mismatch in reference ... > > The relocation at __ex_table+0x447c references section ".irqentry.text" > which is not in the list of authorized sections. > > Add .irqentry.text to OTHER_SECTIONS to cure the issue. > > Reported-by: Sergey Senozhatsky <senozhatsky@chromium.org> I found the context in LKML. Closes: https://lore.kernel.org/all/20241128111844.GE10431@google.com/ However, is this still relevant to the mainline kernel? In Linux 5.4.y, I agree this because smp_apic_timer_interrupt() is annotated as __irq_entry: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/arch/x86/kernel/apic/apic.c?id=v5.4.286#n1145 In this mainline kernel, DEFINE_IDTENTRY_SYSVEC() expands to a normal .text function which is explicitly annotated 'noinline'. > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > Cc: stable@vger.kernel.org > --- > scripts/mod/modpost.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- a/scripts/mod/modpost.c > +++ b/scripts/mod/modpost.c > @@ -785,7 +785,7 @@ static void check_section(const char *mo > ".ltext", ".ltext.*" > #define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \ > ".fixup", ".entry.text", ".exception.text", \ > - ".coldtext", ".softirqentry.text" > + ".coldtext", ".softirqentry.text", ".irqentry.text" > > #define ALL_TEXT_SECTIONS ".init.text", ".exit.text", \ > TEXT_SECTIONS, OTHER_TEXT_SECTIONS -- Best Regards Masahiro Yamada
On (24/12/01 12:17), Thomas Gleixner wrote: > The compiler can fully inline the actual handler function of an interrupt > entry into the .irqentry.text entry point. If such a function contains an > access which has an exception table entry, modpost complains about a > section mismatch: > > WARNING: vmlinux.o(__ex_table+0x447c): Section mismatch in reference ... > > The relocation at __ex_table+0x447c references section ".irqentry.text" > which is not in the list of authorized sections. > > Add .irqentry.text to OTHER_SECTIONS to cure the issue. This works. In fact, this looks like a local fix which we applied here on our side, but we were very unsure. Thank you Thomas.
On Mon, Dec 02 2024 at 11:02, Masahiro Yamada wrote: > On Sun, Dec 1, 2024 at 8:17 PM Thomas Gleixner <tglx@linutronix.de> wrote: >> >> The compiler can fully inline the actual handler function of an interrupt >> entry into the .irqentry.text entry point. If such a function contains an >> access which has an exception table entry, modpost complains about a >> section mismatch: >> >> WARNING: vmlinux.o(__ex_table+0x447c): Section mismatch in reference ... >> >> The relocation at __ex_table+0x447c references section ".irqentry.text" >> which is not in the list of authorized sections. >> >> Add .irqentry.text to OTHER_SECTIONS to cure the issue. >> >> Reported-by: Sergey Senozhatsky <senozhatsky@chromium.org> > > I found the context in LKML. > Closes: https://lore.kernel.org/all/20241128111844.GE10431@google.com/ > > However, is this still relevant to the mainline kernel? > > In Linux 5.4.y, I agree this because smp_apic_timer_interrupt() > is annotated as __irq_entry: Correct. > In this mainline kernel, DEFINE_IDTENTRY_SYSVEC() > expands to a normal .text function which is explicitly > annotated 'noinline'. It's not annotated noinline, it's annotated 'noinstr', which puts the code into the .noinstr.text section. That one is indeed covered. So yes, the fix is only required for pre 5.8 kernels. Thanks, tglx
On Tue, Dec 3, 2024 at 6:03 AM Thomas Gleixner <tglx@linutronix.de> wrote: > > On Mon, Dec 02 2024 at 11:02, Masahiro Yamada wrote: > > On Sun, Dec 1, 2024 at 8:17 PM Thomas Gleixner <tglx@linutronix.de> wrote: > >> > >> The compiler can fully inline the actual handler function of an interrupt > >> entry into the .irqentry.text entry point. If such a function contains an > >> access which has an exception table entry, modpost complains about a > >> section mismatch: > >> > >> WARNING: vmlinux.o(__ex_table+0x447c): Section mismatch in reference ... > >> > >> The relocation at __ex_table+0x447c references section ".irqentry.text" > >> which is not in the list of authorized sections. > >> > >> Add .irqentry.text to OTHER_SECTIONS to cure the issue. > >> > >> Reported-by: Sergey Senozhatsky <senozhatsky@chromium.org> > > > > I found the context in LKML. > > Closes: https://lore.kernel.org/all/20241128111844.GE10431@google.com/ > > > > However, is this still relevant to the mainline kernel? > > > > In Linux 5.4.y, I agree this because smp_apic_timer_interrupt() > > is annotated as __irq_entry: > > Correct. > > > In this mainline kernel, DEFINE_IDTENTRY_SYSVEC() > > expands to a normal .text function which is explicitly > > annotated 'noinline'. > > It's not annotated noinline, it's annotated 'noinstr', which puts the > code into the .noinstr.text section. That one is indeed covered. The callsite of local_apic_timer_interrupt() is annotated 'noinline' if I correctly understand this line: https://github.com/torvalds/linux/blob/v6.13-rc1/arch/x86/include/asm/idtentry.h#L272 It expands to: static noinline void __sysvec_apic_timer_interrupt(struct pt_regs *regs) { [snip] local_apic_timer_interrupt(); [snip] } > So yes, the fix is only required for pre 5.8 kernels. This never occurs on x86 after commit f0178fc01fe46, but theoretically this may occur for other architectures. Now applied to linux-kbuild. Thanks. > > Thanks, > > tglx
On Wed, Dec 04 2024 at 00:27, Masahiro Yamada wrote: > On Tue, Dec 3, 2024 at 6:03 AM Thomas Gleixner <tglx@linutronix.de> wrote: >> > In this mainline kernel, DEFINE_IDTENTRY_SYSVEC() >> > expands to a normal .text function which is explicitly >> > annotated 'noinline'. >> >> It's not annotated noinline, it's annotated 'noinstr', which puts the >> code into the .noinstr.text section. That one is indeed covered. > > The callsite of local_apic_timer_interrupt() is annotated 'noinline' > if I correctly understand this line: > https://github.com/torvalds/linux/blob/v6.13-rc1/arch/x86/include/asm/idtentry.h#L272 You're right. I got lost in the macro maze and looked at the actual sysvec_...() part. >> So yes, the fix is only required for pre 5.8 kernels. > > This never occurs on x86 after commit f0178fc01fe46, > but theoretically this may occur for other architectures. Correct. Thanks, tglx
--- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -785,7 +785,7 @@ static void check_section(const char *mo ".ltext", ".ltext.*" #define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \ ".fixup", ".entry.text", ".exception.text", \ - ".coldtext", ".softirqentry.text" + ".coldtext", ".softirqentry.text", ".irqentry.text" #define ALL_TEXT_SECTIONS ".init.text", ".exit.text", \ TEXT_SECTIONS, OTHER_TEXT_SECTIONS
The compiler can fully inline the actual handler function of an interrupt entry into the .irqentry.text entry point. If such a function contains an access which has an exception table entry, modpost complains about a section mismatch: WARNING: vmlinux.o(__ex_table+0x447c): Section mismatch in reference ... The relocation at __ex_table+0x447c references section ".irqentry.text" which is not in the list of authorized sections. Add .irqentry.text to OTHER_SECTIONS to cure the issue. Reported-by: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org --- scripts/mod/modpost.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)