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author | Gregory Herrero <gregory.herrero@oracle.com> | 2020-07-17 17:33:38 +0300 |
---|---|---|
committer | Catalin Marinas <catalin.marinas@arm.com> | 2020-07-24 14:43:19 +0300 |
commit | ea0eada45632f4807b2f49de951072283e2d781c (patch) | |
tree | ee560e76afec1945003d37825a866a45fc2c3708 /arch/arm64/mm | |
parent | a46cec12f4a53ee5113f42b327cbb8d4cda074d2 (diff) | |
download | linux-ea0eada45632f4807b2f49de951072283e2d781c.tar.xz |
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>
Diffstat (limited to 'arch/arm64/mm')
0 files changed, 0 insertions, 0 deletions