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| author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2019-04-07 21:06:16 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-04-17 08:39:52 +0200 |
| commit | 6b3b09cd4daa81bab35375f54c4548dea930c238 (patch) | |
| tree | ba0a26b5dbf1e66f649ea5435db57b553990fa5a /arch | |
| parent | 36078cae3790ac638013a43a93542a729082272c (diff) | |
| download | linux-6b3b09cd4daa81bab35375f54c4548dea930c238.tar.gz linux-6b3b09cd4daa81bab35375f54c4548dea930c238.tar.bz2 linux-6b3b09cd4daa81bab35375f54c4548dea930c238.zip | |
arm64/ftrace: fix inadvertent BUG() in trampoline check
commit 5a3ae7b314a2259b1188b22b392f5eba01e443ee upstream.
The ftrace trampoline code (which deals with modules loaded out of
BL range of the core kernel) uses plt_entries_equal() to check whether
the per-module trampoline equals a zero buffer, to decide whether the
trampoline has already been initialized.
This triggers a BUG() in the opcode manipulation code, since we end
up checking the ADRP offset of a 0x0 opcode, which is not an ADRP
instruction.
So instead, add a helper to check whether a PLT is initialized, and
call that from the frace code.
Cc: <stable@vger.kernel.org> # v5.0
Fixes: bdb85cd1d206 ("arm64/module: switch to ADRP/ADD sequences for PLT entries")
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/include/asm/module.h | 5 | ||||
| -rw-r--r-- | arch/arm64/kernel/ftrace.c | 3 |
2 files changed, 6 insertions, 2 deletions
diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h index 905e1bb0e7bd..cd9f4e9d04d3 100644 --- a/arch/arm64/include/asm/module.h +++ b/arch/arm64/include/asm/module.h @@ -73,4 +73,9 @@ static inline bool is_forbidden_offset_for_adrp(void *place) struct plt_entry get_plt_entry(u64 dst, void *pc); bool plt_entries_equal(const struct plt_entry *a, const struct plt_entry *b); +static inline bool plt_entry_is_initialized(const struct plt_entry *e) +{ + return e->adrp || e->add || e->br; +} + #endif /* __ASM_MODULE_H */ diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c index 8e4431a8821f..07b298120182 100644 --- a/arch/arm64/kernel/ftrace.c +++ b/arch/arm64/kernel/ftrace.c @@ -107,8 +107,7 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) trampoline = get_plt_entry(addr, mod->arch.ftrace_trampoline); if (!plt_entries_equal(mod->arch.ftrace_trampoline, &trampoline)) { - if (!plt_entries_equal(mod->arch.ftrace_trampoline, - &(struct plt_entry){})) { + if (plt_entry_is_initialized(mod->arch.ftrace_trampoline)) { pr_err("ftrace: far branches to multiple entry points unsupported inside a single module\n"); return -EINVAL; } |