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author | Uros Bizjak <ubizjak@gmail.com> | 2023-11-06 00:34:36 +0300 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2023-11-30 22:06:17 +0300 |
commit | 17bce3b2ae2d52e8c5c12274ce4c3a631ce9e66b (patch) | |
tree | 64fed2ccae63192f4ff0dd193e9fbbc8b2d9a4fc /arch/x86/kernel/callthunks.c | |
parent | 43bda69ed9e3b86d0ba5ff9256e437d50074d7d5 (diff) | |
download | linux-17bce3b2ae2d52e8c5c12274ce4c3a631ce9e66b.tar.xz |
x86/callthunks: Handle %rip-relative relocations in call thunk template
Contrary to alternatives, relocations are currently not supported in
call thunk templates. Re-use the existing infrastructure from
alternative.c to allow %rip-relative relocations when copying call
thunk template from its storage location.
The patch allows unification of ASM_INCREMENT_CALL_DEPTH, which already
uses PER_CPU_VAR macro, with INCREMENT_CALL_DEPTH, used in call thunk
template, which is currently limited to use absolute address.
Reuse existing relocation infrastructure from alternative.c.,
as suggested by Peter Zijlstra.
Signed-off-by: Uros Bizjak <ubizjak@gmail.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20231105213731.1878100-3-ubizjak@gmail.com
Diffstat (limited to 'arch/x86/kernel/callthunks.c')
-rw-r--r-- | arch/x86/kernel/callthunks.c | 32 |
1 files changed, 25 insertions, 7 deletions
diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c index c06bfc086565..f56fa303d643 100644 --- a/arch/x86/kernel/callthunks.c +++ b/arch/x86/kernel/callthunks.c @@ -24,6 +24,8 @@ static int __initdata_or_module debug_callthunks; +#define MAX_PATCH_LEN (255-1) + #define prdbg(fmt, args...) \ do { \ if (debug_callthunks) \ @@ -184,10 +186,15 @@ static const u8 nops[] = { static void *patch_dest(void *dest, bool direct) { unsigned int tsize = SKL_TMPL_SIZE; + u8 insn_buff[MAX_PATCH_LEN]; u8 *pad = dest - tsize; + memcpy(insn_buff, skl_call_thunk_template, tsize); + apply_relocation(insn_buff, tsize, pad, + skl_call_thunk_template, tsize); + /* Already patched? */ - if (!bcmp(pad, skl_call_thunk_template, tsize)) + if (!bcmp(pad, insn_buff, tsize)) return pad; /* Ensure there are nops */ @@ -197,9 +204,9 @@ static void *patch_dest(void *dest, bool direct) } if (direct) - memcpy(pad, skl_call_thunk_template, tsize); + memcpy(pad, insn_buff, tsize); else - text_poke_copy_locked(pad, skl_call_thunk_template, tsize, true); + text_poke_copy_locked(pad, insn_buff, tsize, true); return pad; } @@ -297,20 +304,27 @@ void *callthunks_translate_call_dest(void *dest) static bool is_callthunk(void *addr) { unsigned int tmpl_size = SKL_TMPL_SIZE; - void *tmpl = skl_call_thunk_template; + u8 insn_buff[MAX_PATCH_LEN]; unsigned long dest; + u8 *pad; dest = roundup((unsigned long)addr, CONFIG_FUNCTION_ALIGNMENT); if (!thunks_initialized || skip_addr((void *)dest)) return false; - return !bcmp((void *)(dest - tmpl_size), tmpl, tmpl_size); + *pad = dest - tmpl_size; + + memcpy(insn_buff, skl_call_thunk_template, tmpl_size); + apply_relocation(insn_buff, tmpl_size, pad, + skl_call_thunk_template, tmpl_size); + + return !bcmp(pad, insn_buff, tmpl_size); } int x86_call_depth_emit_accounting(u8 **pprog, void *func) { unsigned int tmpl_size = SKL_TMPL_SIZE; - void *tmpl = skl_call_thunk_template; + u8 insn_buff[MAX_PATCH_LEN]; if (!thunks_initialized) return 0; @@ -319,7 +333,11 @@ int x86_call_depth_emit_accounting(u8 **pprog, void *func) if (func && is_callthunk(func)) return 0; - memcpy(*pprog, tmpl, tmpl_size); + memcpy(insn_buff, skl_call_thunk_template, tmpl_size); + apply_relocation(insn_buff, tmpl_size, *pprog, + skl_call_thunk_template, tmpl_size); + + memcpy(*pprog, insn_buff, tmpl_size); *pprog += tmpl_size; return tmpl_size; } |