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authorJoan Bruguera Micó <joanbrugueram@gmail.com>2024-04-01 21:55:30 +0300
committerAlexei Starovoitov <ast@kernel.org>2024-04-02 06:37:56 +0300
commit6a537453000a916392fcac1acb96c1d9d1e05b74 (patch)
tree69ebdb5ddaa504511a9b2f1e327246b1591ba08e /arch/x86/kernel/callthunks.c
parent9d98aa088386aee3db1b7b60b800c0fde0654a4a (diff)
downloadlinux-6a537453000a916392fcac1acb96c1d9d1e05b74.tar.xz
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.c4
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);