Re: [PATCH -fixes] riscv: Re-introduce global icache flush in patch_text_XXX()

From: Alexandre Ghiti
Date: Thu Aug 01 2024 - 14:48:57 EST


Hi Samuel,

On 01/08/2024 19:32, Samuel Holland wrote:
Hi Alex,

On 2024-07-30 8:59 AM, Alexandre Ghiti wrote:
commit edf2d546bfd6 ("riscv: patch: Flush the icache right after
patching to avoid illegal insns") mistakenly removed the global icache
flush in patch_text_nosync() and patch_text_set_nosync() functions, so
reintroduce them.

Fixes: edf2d546bfd6 ("riscv: patch: Flush the icache right after patching to avoid illegal insns")
Reported-by: Samuel Holland <samuel.holland@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-riscv/CAHVXubh8Adb4=-vN4cSh0FrZ16TeOKJbLj4AF09QC241bRk1Jg@xxxxxxxxxxxxxx/T/#m800757c26f72a1d45c240cb815650430166c82ea
Shouldn't this use the permalink for the specific message, not the thread?


I never paid attention to that, but the permalink is shorter so I'll change that, thanks



Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
---
arch/riscv/kernel/patch.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/arch/riscv/kernel/patch.c b/arch/riscv/kernel/patch.c
index ab03732d06c4..91edfd764ed9 100644
--- a/arch/riscv/kernel/patch.c
+++ b/arch/riscv/kernel/patch.c
@@ -205,6 +205,9 @@ int patch_text_set_nosync(void *addr, u8 c, size_t len)
ret = patch_insn_set(tp, c, len);
+ if (!ret)
+ flush_icache_range((uintptr_t)tp, (uintptr_t)tp + len);
This patch was based on an old tree from before
https://git.kernel.org/riscv/c/47742484ee16 removed the "tp" variable. While it
still compiles because flush_icache_range() is a macro that discards its
arguments, it will be confusing to anyone reading the code.


Hmmm not the first time I hear this :) Sorry, I prepared the patch a couple of weeks ago and the rebase on 6.11-rc1 did not complain, I do that right now and send a new version tomorrow.

Thanks,

Alex



Regards,
Samuel

+
return ret;
}
NOKPROBE_SYMBOL(patch_text_set_nosync);
@@ -237,6 +240,9 @@ int patch_text_nosync(void *addr, const void *insns, size_t len)
ret = patch_insn_write(tp, insns, len);
+ if (!ret)
+ flush_icache_range((uintptr_t) tp, (uintptr_t) tp + len);
+
return ret;
}
NOKPROBE_SYMBOL(patch_text_nosync);

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