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| author | Joan Bruguera Micó <joanbrugueram@gmail.com> | 2024-04-01 20:55:30 +0200 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2024-04-01 20:37:56 -0700 |
| commit | 6a537453000a916392fcac1acb96c1d9d1e05b74 (patch) | |
| tree | 69ebdb5ddaa504511a9b2f1e327246b1591ba08e /arch/x86/kernel/callthunks.c | |
| parent | 9d98aa088386aee3db1b7b60b800c0fde0654a4a (diff) | |
x86/bpf: Fix IP for relocating call depth accounting
The commit:
59bec00ace28 ("x86/percpu: Introduce %rip-relative addressing to PER_CPU_VAR()")
made PER_CPU_VAR() to use rip-relative addressing, hence
INCREMENT_CALL_DEPTH macro and skl_call_thunk_template got rip-relative
asm code inside of it. A follow up commit:
17bce3b2ae2d ("x86/callthunks: Handle %rip-relative relocations in call thunk template")
changed x86_call_depth_emit_accounting() to use apply_relocation(),
but mistakenly assumed that the code is being patched in-place (where
the destination of the relocation matches the address of the code),
using *pprog as the destination ip. This is not true for the call depth
accounting, emitted by the BPF JIT, so the calculated address was wrong,
JIT-ed BPF progs on kernels with call depth tracking got broken and
usually caused a page fault.
Pass the destination IP when the BPF JIT emits call depth accounting.
Fixes: 17bce3b2ae2d ("x86/callthunks: Handle %rip-relative relocations in call thunk template")
Signed-off-by: Joan Bruguera Micó <joanbrugueram@gmail.com>
Reviewed-by: Uros Bizjak <ubizjak@gmail.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/r/20240401185821.224068-3-ubizjak@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'arch/x86/kernel/callthunks.c')
| -rw-r--r-- | arch/x86/kernel/callthunks.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c index 30335182b6b0..e92ff0c11db8 100644 --- a/arch/x86/kernel/callthunks.c +++ b/arch/x86/kernel/callthunks.c @@ -314,7 +314,7 @@ static bool is_callthunk(void *addr) return !bcmp(pad, insn_buff, tmpl_size); } -int x86_call_depth_emit_accounting(u8 **pprog, void *func) +int x86_call_depth_emit_accounting(u8 **pprog, void *func, void *ip) { unsigned int tmpl_size = SKL_TMPL_SIZE; u8 insn_buff[MAX_PATCH_LEN]; @@ -327,7 +327,7 @@ int x86_call_depth_emit_accounting(u8 **pprog, void *func) return 0; memcpy(insn_buff, skl_call_thunk_template, tmpl_size); - apply_relocation(insn_buff, tmpl_size, *pprog, + apply_relocation(insn_buff, tmpl_size, ip, skl_call_thunk_template, tmpl_size); memcpy(*pprog, insn_buff, tmpl_size); |