diff options
| author | Gregory Herrero <gregory.herrero@oracle.com> | 2020-07-17 16:33:38 +0200 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2020-07-24 12:43:19 +0100 |
| commit | ea0eada45632f4807b2f49de951072283e2d781c (patch) | |
| tree | ee560e76afec1945003d37825a866a45fc2c3708 | |
| parent | a46cec12f4a53ee5113f42b327cbb8d4cda074d2 (diff) | |
recordmcount: only record relocation of type R_AARCH64_CALL26 on arm64.
Currently, if a section has a relocation to '_mcount' symbol, a new
__mcount_loc entry will be added whatever the relocation type is.
This is problematic when a relocation to '_mcount' is in the middle of a
section and is not a call for ftrace use.
Such relocation could be generated with below code for example:
bool is_mcount(unsigned long addr)
{
return (target == (unsigned long) &_mcount);
}
With this snippet of code, ftrace will try to patch the mcount location
generated by this code on module load and fail with:
Call trace:
ftrace_bug+0xa0/0x28c
ftrace_process_locs+0x2f4/0x430
ftrace_module_init+0x30/0x38
load_module+0x14f0/0x1e78
__do_sys_finit_module+0x100/0x11c
__arm64_sys_finit_module+0x28/0x34
el0_svc_common+0x88/0x194
el0_svc_handler+0x38/0x8c
el0_svc+0x8/0xc
---[ end trace d828d06b36ad9d59 ]---
ftrace failed to modify
[<ffffa2dbf3a3a41c>] 0xffffa2dbf3a3a41c
actual: 66:a9:3c:90
Initializing ftrace call sites
ftrace record flags: 2000000
(0)
expected tramp: ffffa2dc6cf66724
So Limit the relocation type to R_AARCH64_CALL26 as in perl version of
recordmcount.
Fixes: af64d2aa872a ("ftrace: Add arm64 support to recordmcount")
Signed-off-by: Gregory Herrero <gregory.herrero@oracle.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Link: https://lore.kernel.org/r/20200717143338.19302-1-gregory.herrero@oracle.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
| -rw-r--r-- | scripts/recordmcount.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/scripts/recordmcount.c b/scripts/recordmcount.c index 7225107a9aaf..e59022b3f125 100644 --- a/scripts/recordmcount.c +++ b/scripts/recordmcount.c @@ -434,6 +434,11 @@ static int arm_is_fake_mcount(Elf32_Rel const *rp) return 1; } +static int arm64_is_fake_mcount(Elf64_Rel const *rp) +{ + return ELF64_R_TYPE(w(rp->r_info)) != R_AARCH64_CALL26; +} + /* 64-bit EM_MIPS has weird ELF64_Rela.r_info. * http://techpubs.sgi.com/library/manuals/4000/007-4658-001/pdf/007-4658-001.pdf * We interpret Table 29 Relocation Operation (Elf64_Rel, Elf64_Rela) [p.40] @@ -547,6 +552,7 @@ static int do_file(char const *const fname) make_nop = make_nop_arm64; rel_type_nop = R_AARCH64_NONE; ideal_nop = ideal_nop4_arm64; + is_fake_mcount64 = arm64_is_fake_mcount; break; case EM_IA_64: reltype = R_IA64_IMM64; break; case EM_MIPS: /* reltype: e_class */ break; |