arm64: kprobes: Drop ID map text from kprobes blacklist
PATCH 1/1 arm64: kprobes: Drop ID map text from kprobes blacklist
The ID mapped text region is never accessed via the normal kernel mapping of text, and so it was moved into .rodata instead. This means it is no longer considered as a suitable place for kprobes by default, and the explicit blacklist is unnecessary, and actually results in an error message at boot:
kprobes: Failed to populate blacklist (error -22), kprobes not restricted, be careful using them!
So stop blacklisting the ID map text explicitly.
--- arch/arm64/kernel/probes/kprobes.c | 4 ---- 1 file changed, 4 deletions(-)
arch/arm64/kernel/probes/kprobes.c +0 -4
@@ -387,10 +387,6 @@ int __init arch_populate_kprobe_blacklist(void) (unsigned long)__irqentry_text_end);if (ret)return ret; - ret =kprobe_add_area_blacklist ((unsigned long )__idmap_text_start, - (unsigned long )__idmap_text_end); -if (ret) -return ret; ret =kprobe_add_area_blacklist ((unsigned long )__hyp_text_start, (unsigned long )__hyp_text_end);if (ret ||is_kernel_in_hyp_mode ())
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Quoted 6 lines · Ard Biesheuvel
The ID mapped text region is never accessed via the normal kernel mapping of text, and so it was moved into .rodata instead. This means it is no longer considered as a suitable place for kprobes by default, and the explicit blacklist is unnecessary, and actually results in an error message at boot:
Quoted 7 lines
kprobes: Failed to populate blacklist (error -22), kprobes not restricted, be careful using them!
So stop blacklisting the ID map text explicitly.
Fixes af7249b317e4d0b3d ("arm64: kernel: move identity map out of .text mapping")Reported-by Nathan Chancellor <[email protected]>Signed-off-by Ard Biesheuvel <[email protected]>
Thank you for the quick fix!
Quoted 22 lines
--- arch/arm64/kernel/probes/kprobes.c | 4 ---- 1 file changed, 4 deletions(-)arch/arm64/kernel/probes/kprobes.c +0
-4@@ -387,10 +387,6 @@ int __init arch_populate_kprobe_blacklist(void) (unsigned long)__irqentry_text_end);if (ret)return ret; - ret =kprobe_add_area_blacklist ((unsigned long )__idmap_text_start, - (unsigned long )__idmap_text_end); -if (ret) -return ret; ret =kprobe_add_area_blacklist ((unsigned long )__hyp_text_start, (unsigned long )__hyp_text_end);if (ret ||is_kernel_in_hyp_mode ())Signature · 1 line
2.39.1
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Quoted 6 lines · Ard Biesheuvel
The ID mapped text region is never accessed via the normal kernel mapping of text, and so it was moved into .rodata instead. This means it is no longer considered as a suitable place for kprobes by default, and the explicit blacklist is unnecessary, and actually results in an error message at boot:
Quoted 7 lines
kprobes: Failed to populate blacklist (error -22), kprobes not restricted, be careful using them!
So stop blacklisting the ID map text explicitly.
Fixes af7249b317e4d0b3d ("arm64: kernel: move identity map out of .text mapping")Reported-by Nathan Chancellor <[email protected]>Signed-off-by Ard Biesheuvel <[email protected]>
Mark.
Quoted 27 lines
--- arch/arm64/kernel/probes/kprobes.c | 4 ---- 1 file changed, 4 deletions(-)arch/arm64/kernel/probes/kprobes.c +0
-4@@ -387,10 +387,6 @@ int __init arch_populate_kprobe_blacklist(void) (unsigned long)__irqentry_text_end);if (ret)return ret; - ret =kprobe_add_area_blacklist ((unsigned long )__idmap_text_start, - (unsigned long )__idmap_text_end); -if (ret) -return ret; ret =kprobe_add_area_blacklist ((unsigned long )__hyp_text_start, (unsigned long )__hyp_text_end);if (ret ||is_kernel_in_hyp_mode ())Signature · 7 lines
2.39.1 _______________________________________________ linux-arm-kernel mailing list [email protected] http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
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Catalin Marinas
maintainerQuoted 9 lines · Ard Biesheuvel
The ID mapped text region is never accessed via the normal kernel mapping of text, and so it was moved into .rodata instead. This means it is no longer considered as a suitable place for kprobes by default, and the explicit blacklist is unnecessary, and actually results in an error message at boot:
kprobes: Failed to populate blacklist (error -22), kprobes not restricted, be careful using them!
[...]
Applied to arm64 (for-next/efi-boot-mmu-on), thanks!
[1/1] arm64: kprobes: Drop ID map text from kprobes blacklist
https://git.kernel.org/arm64/c/a088cf8eee12
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