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* [PATCH 0/2] ftrace fixes
@ 2024-03-26 20:30 Alexandre Ghiti
  2024-03-26 20:30 ` [PATCH 1/2] riscv: Fix warning by declaring arch_cpu_idle() as noinstr Alexandre Ghiti
                   ` (3 more replies)
  0 siblings, 4 replies; 6+ messages in thread
From: Alexandre Ghiti @ 2024-03-26 20:30 UTC (permalink / raw)
  To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Jisheng Zhang,
	Björn Töpel, Pu Lehui, Daniel Borkmann, Puranjay Mohan,
	Zong Li, Masami Hiramatsu, linux-riscv, linux-kernel
  Cc: Alexandre Ghiti

Both were reported recently as there are efforts ongoing to
reimplement ftrace on riscv and both are independent of this rework,
so here they are.

Alexandre Ghiti (2):
  riscv: Fix warning by declaring arch_cpu_idle() as noinstr
  riscv: Disable preemption when using patch_map()

 arch/riscv/kernel/patch.c   | 8 ++++++++
 arch/riscv/kernel/process.c | 2 +-
 2 files changed, 9 insertions(+), 1 deletion(-)

-- 
2.39.2


^ permalink raw reply	[flat|nested] 6+ messages in thread
* [PATCH 1/2] riscv: Fix warning by declaring arch_cpu_idle() as noinstr
  2024-03-26 20:30 [PATCH 0/2] ftrace fixes Alexandre Ghiti
@ 2024-03-26 20:30 ` Alexandre Ghiti
  2024-03-27 14:23   ` Andy Chiu
  2024-03-26 20:30 ` [PATCH 2/2] riscv: Disable preemption when using patch_map() Alexandre Ghiti
                   ` (2 subsequent siblings)
  3 siblings, 1 reply; 6+ messages in thread
From: Alexandre Ghiti @ 2024-03-26 20:30 UTC (permalink / raw)
  To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Jisheng Zhang,
	Björn Töpel, Pu Lehui, Daniel Borkmann, Puranjay Mohan,
	Zong Li, Masami Hiramatsu, linux-riscv, linux-kernel
  Cc: Alexandre Ghiti, Evgenii Shatokhin

The following warning appears when using ftrace:

[89855.443413] RCU not on for: arch_cpu_idle+0x0/0x1c
[89855.445640] WARNING: CPU: 5 PID: 0 at include/linux/trace_recursion.h:162 arch_ftrace_ops_list_func+0x208/0x228
[89855.445824] Modules linked in: xt_conntrack(E) nft_chain_nat(E) xt_MASQUERADE(E) nf_conntrack_netlink(E) xt_addrtype(E) nft_compat(E) nf_tables(E) nfnetlink(E) br_netfilter(E) cfg80211(E) nls_iso8859_1(E) ofpart(E) redboot(E) cmdlinepart(E) cfi_cmdset_0001(E) virtio_net(E) cfi_probe(E) cfi_util(E) 9pnet_virtio(E) gen_probe(E) net_failover(E) virtio_rng(E) failover(E) 9pnet(E) physmap(E) map_funcs(E) chipreg(E) mtd(E) uio_pdrv_genirq(E) uio(E) dm_multipath(E) scsi_dh_rdac(E) scsi_dh_emc(E) scsi_dh_alua(E) drm(E) efi_pstore(E) backlight(E) ip_tables(E) x_tables(E) raid10(E) raid456(E) async_raid6_recov(E) async_memcpy(E) async_pq(E) async_xor(E) xor(E) async_tx(E) raid6_pq(E) raid1(E) raid0(E) virtio_blk(E)
[89855.451563] CPU: 5 PID: 0 Comm: swapper/5 Tainted: G            E      6.8.0-rc6ubuntu-defconfig #2
[89855.451726] Hardware name: riscv-virtio,qemu (DT)
[89855.451899] epc : arch_ftrace_ops_list_func+0x208/0x228
[89855.452016]  ra : arch_ftrace_ops_list_func+0x208/0x228
[89855.452119] epc : ffffffff8016b216 ra : ffffffff8016b216 sp : ffffaf808090fdb0
[89855.452171]  gp : ffffffff827c7680 tp : ffffaf808089ad40 t0 : ffffffff800c0dd8
[89855.452216]  t1 : 0000000000000001 t2 : 0000000000000000 s0 : ffffaf808090fe30
[89855.452306]  s1 : 0000000000000000 a0 : 0000000000000026 a1 : ffffffff82cd6ac8
[89855.452423]  a2 : ffffffff800458c8 a3 : ffffaf80b1870640 a4 : 0000000000000000
[89855.452646]  a5 : 0000000000000000 a6 : 00000000ffffffff a7 : ffffffffffffffff
[89855.452698]  s2 : ffffffff82766872 s3 : ffffffff80004caa s4 : ffffffff80ebea90
[89855.452743]  s5 : ffffaf808089bd40 s6 : 8000000a00006e00 s7 : 0000000000000008
[89855.452787]  s8 : 0000000000002000 s9 : 0000000080043700 s10: 0000000000000000
[89855.452831]  s11: 0000000000000000 t3 : 0000000000100000 t4 : 0000000000000064
[89855.452874]  t5 : 000000000000000c t6 : ffffaf80b182dbfc
[89855.452929] status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000003
[89855.453053] [<ffffffff8016b216>] arch_ftrace_ops_list_func+0x208/0x228
[89855.453191] [<ffffffff8000e082>] ftrace_call+0x8/0x22
[89855.453265] [<ffffffff800a149c>] do_idle+0x24c/0x2ca
[89855.453357] [<ffffffff8000da54>] return_to_handler+0x0/0x26
[89855.453429] [<ffffffff8000b716>] smp_callin+0x92/0xb6
[89855.453785] ---[ end trace 0000000000000000 ]---

To fix this, mark arch_cpu_idle() as noinstr, like it is done in commit
a9cbc1b471d2 ("s390/idle: mark arch_cpu_idle() noinstr").

Reported-by: Evgenii Shatokhin <e.shatokhin@yadro.com>
Closes: https://lore.kernel.org/linux-riscv/51f21b87-ebed-4411-afbc-c00d3dea2bab@yadro.com/
Fixes: cfbc4f81c9d0 ("riscv: Select ARCH_WANTS_NO_INSTR")
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/kernel/process.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 92922dbd5b5c..6abeecbfc51d 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -37,7 +37,7 @@ EXPORT_SYMBOL(__stack_chk_guard);
 
 extern asmlinkage void ret_from_fork(void);
 
-void arch_cpu_idle(void)
+void noinstr arch_cpu_idle(void)
 {
 	cpu_do_idle();
 }
-- 
2.39.2


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* [PATCH 2/2] riscv: Disable preemption when using patch_map()
  2024-03-26 20:30 [PATCH 0/2] ftrace fixes Alexandre Ghiti
  2024-03-26 20:30 ` [PATCH 1/2] riscv: Fix warning by declaring arch_cpu_idle() as noinstr Alexandre Ghiti
@ 2024-03-26 20:30 ` Alexandre Ghiti
  2024-03-26 22:30 ` [PATCH 0/2] ftrace fixes Puranjay Mohan
  2024-04-04 22:20 ` patchwork-bot+linux-riscv
  3 siblings, 0 replies; 6+ messages in thread
From: Alexandre Ghiti @ 2024-03-26 20:30 UTC (permalink / raw)
  To: Paul Walmsley, Palmer Dabbelt, Albert Ou, Jisheng Zhang,
	Björn Töpel, Pu Lehui, Daniel Borkmann, Puranjay Mohan,
	Zong Li, Masami Hiramatsu, linux-riscv, linux-kernel
  Cc: Alexandre Ghiti, Andrea Parri, Andy Chiu

patch_map() uses fixmap mappings to circumvent the non-writability of
the kernel text mapping.

The __set_fixmap() function only flushes the current cpu tlb, it does
not emit an IPI so we must make sure that while we use a fixmap mapping,
the current task is not migrated on another cpu which could miss the
newly introduced fixmap mapping.

So in order to avoid any task migration, disable the preemption.

Reported-by: Andrea Parri <andrea@rivosinc.com>
Closes: https://lore.kernel.org/all/ZcS+GAaM25LXsBOl@andrea/
Reported-by: Andy Chiu <andy.chiu@sifive.com>
Closes: https://lore.kernel.org/linux-riscv/CABgGipUMz3Sffu-CkmeUB1dKVwVQ73+7=sgC45-m0AE9RCjOZg@mail.gmail.com/
Fixes: cad539baa48f ("riscv: implement a memset like function for text")
Fixes: 0ff7c3b33127 ("riscv: Use text_mutex instead of patch_lock")
Co-developed-by: Andy Chiu <andy.chiu@sifive.com>
Signed-off-by: Andy Chiu <andy.chiu@sifive.com>
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
---
 arch/riscv/kernel/patch.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
index 37e87fdcf6a0..30e12b310cab 100644
--- a/arch/riscv/kernel/patch.c
+++ b/arch/riscv/kernel/patch.c
@@ -80,6 +80,8 @@ static int __patch_insn_set(void *addr, u8 c, size_t len)
 	 */
 	lockdep_assert_held(&text_mutex);
 
+	preempt_disable();
+
 	if (across_pages)
 		patch_map(addr + PAGE_SIZE, FIX_TEXT_POKE1);
 
@@ -92,6 +94,8 @@ static int __patch_insn_set(void *addr, u8 c, size_t len)
 	if (across_pages)
 		patch_unmap(FIX_TEXT_POKE1);
 
+	preempt_enable();
+
 	return 0;
 }
 NOKPROBE_SYMBOL(__patch_insn_set);
@@ -122,6 +126,8 @@ static int __patch_insn_write(void *addr, const void *insn, size_t len)
 	if (!riscv_patch_in_stop_machine)
 		lockdep_assert_held(&text_mutex);
 
+	preempt_disable();
+
 	if (across_pages)
 		patch_map(addr + PAGE_SIZE, FIX_TEXT_POKE1);
 
@@ -134,6 +140,8 @@ static int __patch_insn_write(void *addr, const void *insn, size_t len)
 	if (across_pages)
 		patch_unmap(FIX_TEXT_POKE1);
 
+	preempt_enable();
+
 	return ret;
 }
 NOKPROBE_SYMBOL(__patch_insn_write);
-- 
2.39.2


^ permalink raw reply related	[flat|nested] 6+ messages in thread
* Re: [PATCH 0/2] ftrace fixes
  2024-03-26 20:30 [PATCH 0/2] ftrace fixes Alexandre Ghiti
  2024-03-26 20:30 ` [PATCH 1/2] riscv: Fix warning by declaring arch_cpu_idle() as noinstr Alexandre Ghiti
  2024-03-26 20:30 ` [PATCH 2/2] riscv: Disable preemption when using patch_map() Alexandre Ghiti
@ 2024-03-26 22:30 ` Puranjay Mohan
  2024-04-04 22:20 ` patchwork-bot+linux-riscv
  3 siblings, 0 replies; 6+ messages in thread
From: Puranjay Mohan @ 2024-03-26 22:30 UTC (permalink / raw)
  To: Alexandre Ghiti, Paul Walmsley, Palmer Dabbelt, Albert Ou,
	Jisheng Zhang, Björn Töpel, Pu Lehui, Daniel Borkmann,
	Zong Li, Masami Hiramatsu, linux-riscv, linux-kernel
  Cc: Alexandre Ghiti

Alexandre Ghiti <alexghiti@rivosinc.com> writes:

> Both were reported recently as there are efforts ongoing to
> reimplement ftrace on riscv and both are independent of this rework,
> so here they are.
>
> Alexandre Ghiti (2):
>   riscv: Fix warning by declaring arch_cpu_idle() as noinstr
>   riscv: Disable preemption when using patch_map()
>

Thanks for this.

Acked-by: Puranjay Mohan <puranjay12@gmail.com>

for both patches.

Puranjay

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH 1/2] riscv: Fix warning by declaring arch_cpu_idle() as noinstr
  2024-03-26 20:30 ` [PATCH 1/2] riscv: Fix warning by declaring arch_cpu_idle() as noinstr Alexandre Ghiti
@ 2024-03-27 14:23   ` Andy Chiu
  0 siblings, 0 replies; 6+ messages in thread
From: Andy Chiu @ 2024-03-27 14:23 UTC (permalink / raw)
  To: Alexandre Ghiti
  Cc: Paul Walmsley, Palmer Dabbelt, Albert Ou, Jisheng Zhang,
	Björn Töpel, Pu Lehui, Daniel Borkmann, Puranjay Mohan,
	Zong Li, Masami Hiramatsu, linux-riscv, linux-kernel,
	Evgenii Shatokhin

On Wed, Mar 27, 2024 at 4:33 AM Alexandre Ghiti <alexghiti@rivosinc.com> wrote:
>
> The following warning appears when using ftrace:
>
> [89855.443413] RCU not on for: arch_cpu_idle+0x0/0x1c
> [89855.445640] WARNING: CPU: 5 PID: 0 at include/linux/trace_recursion.h:162 arch_ftrace_ops_list_func+0x208/0x228
> [89855.445824] Modules linked in: xt_conntrack(E) nft_chain_nat(E) xt_MASQUERADE(E) nf_conntrack_netlink(E) xt_addrtype(E) nft_compat(E) nf_tables(E) nfnetlink(E) br_netfilter(E) cfg80211(E) nls_iso8859_1(E) ofpart(E) redboot(E) cmdlinepart(E) cfi_cmdset_0001(E) virtio_net(E) cfi_probe(E) cfi_util(E) 9pnet_virtio(E) gen_probe(E) net_failover(E) virtio_rng(E) failover(E) 9pnet(E) physmap(E) map_funcs(E) chipreg(E) mtd(E) uio_pdrv_genirq(E) uio(E) dm_multipath(E) scsi_dh_rdac(E) scsi_dh_emc(E) scsi_dh_alua(E) drm(E) efi_pstore(E) backlight(E) ip_tables(E) x_tables(E) raid10(E) raid456(E) async_raid6_recov(E) async_memcpy(E) async_pq(E) async_xor(E) xor(E) async_tx(E) raid6_pq(E) raid1(E) raid0(E) virtio_blk(E)
> [89855.451563] CPU: 5 PID: 0 Comm: swapper/5 Tainted: G            E      6.8.0-rc6ubuntu-defconfig #2
> [89855.451726] Hardware name: riscv-virtio,qemu (DT)
> [89855.451899] epc : arch_ftrace_ops_list_func+0x208/0x228
> [89855.452016]  ra : arch_ftrace_ops_list_func+0x208/0x228
> [89855.452119] epc : ffffffff8016b216 ra : ffffffff8016b216 sp : ffffaf808090fdb0
> [89855.452171]  gp : ffffffff827c7680 tp : ffffaf808089ad40 t0 : ffffffff800c0dd8
> [89855.452216]  t1 : 0000000000000001 t2 : 0000000000000000 s0 : ffffaf808090fe30
> [89855.452306]  s1 : 0000000000000000 a0 : 0000000000000026 a1 : ffffffff82cd6ac8
> [89855.452423]  a2 : ffffffff800458c8 a3 : ffffaf80b1870640 a4 : 0000000000000000
> [89855.452646]  a5 : 0000000000000000 a6 : 00000000ffffffff a7 : ffffffffffffffff
> [89855.452698]  s2 : ffffffff82766872 s3 : ffffffff80004caa s4 : ffffffff80ebea90
> [89855.452743]  s5 : ffffaf808089bd40 s6 : 8000000a00006e00 s7 : 0000000000000008
> [89855.452787]  s8 : 0000000000002000 s9 : 0000000080043700 s10: 0000000000000000
> [89855.452831]  s11: 0000000000000000 t3 : 0000000000100000 t4 : 0000000000000064
> [89855.452874]  t5 : 000000000000000c t6 : ffffaf80b182dbfc
> [89855.452929] status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000003
> [89855.453053] [<ffffffff8016b216>] arch_ftrace_ops_list_func+0x208/0x228
> [89855.453191] [<ffffffff8000e082>] ftrace_call+0x8/0x22
> [89855.453265] [<ffffffff800a149c>] do_idle+0x24c/0x2ca
> [89855.453357] [<ffffffff8000da54>] return_to_handler+0x0/0x26
> [89855.453429] [<ffffffff8000b716>] smp_callin+0x92/0xb6
> [89855.453785] ---[ end trace 0000000000000000 ]---
>
> To fix this, mark arch_cpu_idle() as noinstr, like it is done in commit
> a9cbc1b471d2 ("s390/idle: mark arch_cpu_idle() noinstr").
>
> Reported-by: Evgenii Shatokhin <e.shatokhin@yadro.com>
> Closes: https://lore.kernel.org/linux-riscv/51f21b87-ebed-4411-afbc-c00d3dea2bab@yadro.com/
> Fixes: cfbc4f81c9d0 ("riscv: Select ARCH_WANTS_NO_INSTR")
> Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>

Reviewed-by: Andy Chiu <andy.chiu@sifive.com>
Tested-by: Andy Chiu <andy.chiu@sifive.com>

> ---
>  arch/riscv/kernel/process.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
> index 92922dbd5b5c..6abeecbfc51d 100644
> --- a/arch/riscv/kernel/process.c
> +++ b/arch/riscv/kernel/process.c
> @@ -37,7 +37,7 @@ EXPORT_SYMBOL(__stack_chk_guard);
>
>  extern asmlinkage void ret_from_fork(void);
>
> -void arch_cpu_idle(void)
> +void noinstr arch_cpu_idle(void)
>  {
>         cpu_do_idle();
>  }
> --
> 2.39.2
>
>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

^ permalink raw reply	[flat|nested] 6+ messages in thread
* Re: [PATCH 0/2] ftrace fixes
  2024-03-26 20:30 [PATCH 0/2] ftrace fixes Alexandre Ghiti
                   ` (2 preceding siblings ...)
  2024-03-26 22:30 ` [PATCH 0/2] ftrace fixes Puranjay Mohan
@ 2024-04-04 22:20 ` patchwork-bot+linux-riscv
  3 siblings, 0 replies; 6+ messages in thread
From: patchwork-bot+linux-riscv @ 2024-04-04 22:20 UTC (permalink / raw)
  To: Alexandre Ghiti
  Cc: linux-riscv, paul.walmsley, palmer, aou, jszhang, bjorn, pulehui,
	daniel, puranjay12, zong.li, mhiramat, linux-kernel

Hello:

This series was applied to riscv/linux.git (fixes)
by Palmer Dabbelt <palmer@rivosinc.com>:

On Tue, 26 Mar 2024 21:30:15 +0100 you wrote:
> Both were reported recently as there are efforts ongoing to
> reimplement ftrace on riscv and both are independent of this rework,
> so here they are.
> 
> Alexandre Ghiti (2):
>   riscv: Fix warning by declaring arch_cpu_idle() as noinstr
>   riscv: Disable preemption when using patch_map()
> 
> [...]

Here is the summary with links:
  - [1/2] riscv: Fix warning by declaring arch_cpu_idle() as noinstr
    https://git.kernel.org/riscv/c/8a48ea87ce89
  - [2/2] riscv: Disable preemption when using patch_map()
    https://git.kernel.org/riscv/c/a370c2419e46

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html



^ permalink raw reply	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2024-04-04 22:20 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2024-03-26 20:30 [PATCH 0/2] ftrace fixes Alexandre Ghiti
2024-03-26 20:30 ` [PATCH 1/2] riscv: Fix warning by declaring arch_cpu_idle() as noinstr Alexandre Ghiti
2024-03-27 14:23   ` Andy Chiu
2024-03-26 20:30 ` [PATCH 2/2] riscv: Disable preemption when using patch_map() Alexandre Ghiti
2024-03-26 22:30 ` [PATCH 0/2] ftrace fixes Puranjay Mohan
2024-04-04 22:20 ` patchwork-bot+linux-riscv

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