[tip: x86/paravirt] x86/paravirt: Remove no longer needed paravirt patching code
From: tip-bot2 for Juergen Gross
Date: Thu Dec 14 2023 - 06:37:05 EST
The following commit has been merged into the x86/paravirt branch of tip:
Commit-ID: f7af6977621a41661696d94c0c0a20c761404476
Gitweb: https://git.kernel.org/tip/f7af6977621a41661696d94c0c0a20c761404476
Author: Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Sun, 10 Dec 2023 07:21:38 +01:00
Committer: Borislav Petkov (AMD) <bp@xxxxxxxxx>
CommitterDate: Sun, 10 Dec 2023 23:34:37 +01:00
x86/paravirt: Remove no longer needed paravirt patching code
Now that paravirt is using the alternatives patching infrastructure,
remove the paravirt patching code.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20231210062138.2417-6-jgross@xxxxxxxx
---
arch/x86/include/asm/paravirt.h | 13 +-----
arch/x86/include/asm/paravirt_types.h | 38 +---------------
arch/x86/include/asm/text-patching.h | 12 +-----
arch/x86/kernel/alternative.c | 67 +--------------------------
arch/x86/kernel/paravirt.c | 30 +------------
arch/x86/kernel/vmlinux.lds.S | 13 +-----
arch/x86/tools/relocs.c | 2 +-
7 files changed, 3 insertions(+), 172 deletions(-)
diff --git a/arch/x86/include/asm/paravirt.h b/arch/x86/include/asm/paravirt.h
index 973c2ac..8bcf758 100644
--- a/arch/x86/include/asm/paravirt.h
+++ b/arch/x86/include/asm/paravirt.h
@@ -725,23 +725,10 @@ void native_pv_lock_init(void) __init;
#else /* __ASSEMBLY__ */
-#define _PVSITE(ptype, ops) \
-771:; \
- ops; \
-772:; \
- .pushsection .parainstructions,"a"; \
- .long 771b-.; \
- .byte ptype; \
- .byte 772b-771b; \
- .popsection
-
-
#ifdef CONFIG_X86_64
#ifdef CONFIG_PARAVIRT_XXL
#ifdef CONFIG_DEBUG_ENTRY
-#define PARA_PATCH(off) ((off) / 8)
-#define PARA_SITE(ptype, ops) _PVSITE(ptype, ops)
#define PARA_INDIRECT(addr) *addr(%rip)
.macro PARA_IRQ_save_fl
diff --git a/arch/x86/include/asm/paravirt_types.h b/arch/x86/include/asm/paravirt_types.h
index 9cad536..d8e85d2 100644
--- a/arch/x86/include/asm/paravirt_types.h
+++ b/arch/x86/include/asm/paravirt_types.h
@@ -2,15 +2,6 @@
#ifndef _ASM_X86_PARAVIRT_TYPES_H
#define _ASM_X86_PARAVIRT_TYPES_H
-#ifndef __ASSEMBLY__
-/* These all sit in the .parainstructions section to tell us what to patch. */
-struct paravirt_patch_site {
- s32 instr_offset; /* original instructions */
- u8 type; /* type of this instruction */
- u8 len; /* length of original instruction */
-} __packed;
-#endif
-
#ifdef CONFIG_PARAVIRT
#ifndef __ASSEMBLY__
@@ -250,32 +241,6 @@ struct paravirt_patch_template {
extern struct pv_info pv_info;
extern struct paravirt_patch_template pv_ops;
-#define PARAVIRT_PATCH(x) \
- (offsetof(struct paravirt_patch_template, x) / sizeof(void *))
-
-#define paravirt_type(op) \
- [paravirt_typenum] "i" (PARAVIRT_PATCH(op)), \
- [paravirt_opptr] "m" (pv_ops.op)
-/*
- * Generate some code, and mark it as patchable by the
- * apply_paravirt() alternate instruction patcher.
- */
-#define _paravirt_alt(insn_string, type) \
- "771:\n\t" insn_string "\n" "772:\n" \
- ".pushsection .parainstructions,\"a\"\n" \
- " .long 771b-.\n" \
- " .byte " type "\n" \
- " .byte 772b-771b\n" \
- ".popsection\n"
-
-/* Generate patchable code, with the default asm parameters. */
-#define paravirt_alt(insn_string) \
- _paravirt_alt(insn_string, "%c[paravirt_typenum]")
-
-/* Simple instruction patching code. */
-#define NATIVE_LABEL(a,x,b) "\n\t.globl " a #x "_" #b "\n" a #x "_" #b ":\n\t"
-
-unsigned int paravirt_patch(u8 type, void *insn_buff, unsigned long addr, unsigned int len);
#define paravirt_ptr(op) [paravirt_opptr] "m" (pv_ops.op)
int paravirt_disable_iospace(void);
@@ -555,9 +520,6 @@ unsigned long pv_native_read_cr2(void);
#define paravirt_nop ((void *)nop_func)
-extern struct paravirt_patch_site __parainstructions[],
- __parainstructions_end[];
-
#endif /* __ASSEMBLY__ */
#define ALT_NOT_XEN ALT_NOT(X86_FEATURE_XENPV)
diff --git a/arch/x86/include/asm/text-patching.h b/arch/x86/include/asm/text-patching.h
index 29832c3..0b70653 100644
--- a/arch/x86/include/asm/text-patching.h
+++ b/arch/x86/include/asm/text-patching.h
@@ -6,18 +6,6 @@
#include <linux/stddef.h>
#include <asm/ptrace.h>
-struct paravirt_patch_site;
-#ifdef CONFIG_PARAVIRT
-void apply_paravirt(struct paravirt_patch_site *start,
- struct paravirt_patch_site *end);
-#else
-static inline void apply_paravirt(struct paravirt_patch_site *start,
- struct paravirt_patch_site *end)
-{}
-#define __parainstructions NULL
-#define __parainstructions_end NULL
-#endif
-
/*
* Currently, the max observed size in the kernel code is
* JUMP_LABEL_NOP_SIZE/RELATIVEJUMP_SIZE, which are 5.
diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 48938bc..f26983a 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -1472,48 +1472,6 @@ int alternatives_text_reserved(void *start, void *end)
}
#endif /* CONFIG_SMP */
-#ifdef CONFIG_PARAVIRT
-
-/* Use this to add nops to a buffer, then text_poke the whole buffer. */
-static void __init_or_module add_nops(void *insns, unsigned int len)
-{
- while (len > 0) {
- unsigned int noplen = len;
- if (noplen > ASM_NOP_MAX)
- noplen = ASM_NOP_MAX;
- memcpy(insns, x86_nops[noplen], noplen);
- insns += noplen;
- len -= noplen;
- }
-}
-
-void __init_or_module apply_paravirt(struct paravirt_patch_site *start,
- struct paravirt_patch_site *end)
-{
- struct paravirt_patch_site *p;
- char insn_buff[MAX_PATCH_LEN];
- u8 *instr;
-
- for (p = start; p < end; p++) {
- unsigned int used;
-
- instr = (u8 *)&p->instr_offset + p->instr_offset;
- BUG_ON(p->len > MAX_PATCH_LEN);
- /* prep the buffer with the original instructions */
- memcpy(insn_buff, instr, p->len);
- used = paravirt_patch(p->type, insn_buff, (unsigned long)instr, p->len);
-
- BUG_ON(used > p->len);
-
- /* Pad the rest with nops */
- add_nops(insn_buff + used, p->len - used);
- text_poke_early(instr, insn_buff, p->len);
- }
-}
-extern struct paravirt_patch_site __start_parainstructions[],
- __stop_parainstructions[];
-#endif /* CONFIG_PARAVIRT */
-
/*
* Self-test for the INT3 based CALL emulation code.
*
@@ -1649,28 +1607,11 @@ void __init alternative_instructions(void)
*/
/*
- * Paravirt patching and alternative patching can be combined to
- * replace a function call with a short direct code sequence (e.g.
- * by setting a constant return value instead of doing that in an
- * external function).
- * In order to make this work the following sequence is required:
- * 1. set (artificial) features depending on used paravirt
- * functions which can later influence alternative patching
- * 2. apply paravirt patching (generally replacing an indirect
- * function call with a direct one)
- * 3. apply alternative patching (e.g. replacing a direct function
- * call with a custom code sequence)
- * Doing paravirt patching after alternative patching would clobber
- * the optimization of the custom code with a function call again.
+ * Make sure to set (artificial) features depending on used paravirt
+ * functions which can later influence alternative patching.
*/
paravirt_set_cap();
- /*
- * First patch paravirt functions, such that we overwrite the indirect
- * call with the direct call.
- */
- apply_paravirt(__parainstructions, __parainstructions_end);
-
__apply_fineibt(__retpoline_sites, __retpoline_sites_end,
__cfi_sites, __cfi_sites_end, true);
@@ -1681,10 +1622,6 @@ void __init alternative_instructions(void)
apply_retpolines(__retpoline_sites, __retpoline_sites_end);
apply_returns(__return_sites, __return_sites_end);
- /*
- * Then patch alternatives, such that those paravirt calls that are in
- * alternatives can be overwritten by their immediate fragments.
- */
apply_alternatives(__alt_instructions, __alt_instructions_end);
/*
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index acc5b10..5358d43 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -43,14 +43,6 @@ void __init default_banner(void)
pv_info.name);
}
-static unsigned paravirt_patch_call(void *insn_buff, const void *target,
- unsigned long addr, unsigned len)
-{
- __text_gen_insn(insn_buff, CALL_INSN_OPCODE,
- (void *)addr, target, CALL_INSN_SIZE);
- return CALL_INSN_SIZE;
-}
-
#ifdef CONFIG_PARAVIRT_XXL
DEFINE_ASM_FUNC(_paravirt_ident_64, "mov %rdi, %rax", .text);
DEFINE_ASM_FUNC(pv_native_save_fl, "pushf; pop %rax", .noinstr.text);
@@ -73,28 +65,6 @@ static void native_tlb_remove_table(struct mmu_gather *tlb, void *table)
tlb_remove_page(tlb, table);
}
-unsigned int paravirt_patch(u8 type, void *insn_buff, unsigned long addr,
- unsigned int len)
-{
- /*
- * Neat trick to map patch type back to the call within the
- * corresponding structure.
- */
- void *opfunc = *((void **)&pv_ops + type);
- unsigned ret;
-
- if (opfunc == NULL)
- /* If there's no function, patch it with BUG_func() */
- ret = paravirt_patch_call(insn_buff, BUG_func, addr, len);
- else if (opfunc == nop_func)
- ret = 0;
- else
- /* Otherwise call the function. */
- ret = paravirt_patch_call(insn_buff, opfunc, addr, len);
-
- return ret;
-}
-
struct static_key paravirt_steal_enabled;
struct static_key paravirt_steal_rq_enabled;
diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index 54a5596..a349dbf 100644
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -267,19 +267,6 @@ SECTIONS
}
#endif
- /*
- * start address and size of operations which during runtime
- * can be patched with virtualization friendly instructions or
- * baremetal native ones. Think page table operations.
- * Details in paravirt_types.h
- */
- . = ALIGN(8);
- .parainstructions : AT(ADDR(.parainstructions) - LOAD_OFFSET) {
- __parainstructions = .;
- *(.parainstructions)
- __parainstructions_end = .;
- }
-
#ifdef CONFIG_RETPOLINE
/*
* List of instructions that call/jmp/jcc to retpoline thunks
diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c
index d30949e..a3bae2b 100644
--- a/arch/x86/tools/relocs.c
+++ b/arch/x86/tools/relocs.c
@@ -66,7 +66,7 @@ static const char * const sym_regex_kernel[S_NSYMTYPES] = {
[S_REL] =
"^(__init_(begin|end)|"
"__x86_cpu_dev_(start|end)|"
- "(__parainstructions|__alt_instructions)(_end)?|"
+ "__alt_instructions(_end)?|"
"(__iommu_table|__apicdrivers|__smp_locks)(_end)?|"
"__(start|end)_pci_.*|"
#if CONFIG_FW_LOADER