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ANDROID: KVM: arm64: Resolve hyp module addresses using ELF sections

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Resolving the addresses of the hypervisor sections within a loadable
module using symbol assignment is fragile, particularly in the face of
mergeable sections (i.e. those emitted with SHF_MERGE by the compiler).

Instead, parse the ELF .hyp.* sections directly and remove the need for
global symbols in the hypervisor module linker script.

Signed-off-by: Will Deacon <will@kernel.org>
[will: Preserve function_nocfi() calls which aren't needed in android14-6.1]
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 261855285
Change-Id: I91d88e1a341b91ffe52ffc770dddc9b46ccb3aa4
This commit is contained in:
Will Deacon
2023-01-05 23:24:26 +00:00
parent 19b5efdcd2
commit ace5025390
8 changed files with 130 additions and 74 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
arch/arm64/Kconfig
View File

@@ -141,6 +141,7 @@ config ARM64
select GENERIC_VDSO_TIME_NS
select HANDLE_DOMAIN_IRQ
select HARDIRQS_SW_RESEND
select HAVE_MOD_ARCH_SPECIFIC if (ARM64_MODULE_PLTS || KVM)
select HAVE_MOVE_PMD
select HAVE_MOVE_PUD
select HAVE_PCI
@@ -1933,7 +1934,6 @@ config ARM64_SVE
config ARM64_MODULE_PLTS
bool "Use PLTs to allow module memory to spill over into vmalloc area"
depends on MODULES
select HAVE_MOD_ARCH_SPECIFIC
help
Allocate PLTs when loading modules so that jumps and calls whose
targets are too far away for their relative offsets to be encoded

3
arch/arm64/include/asm/kvm_mmu.h
View File

@@ -122,9 +122,6 @@ void kvm_update_va_mask(struct alt_instr *alt,
__le32 *origptr, __le32 *updptr, int nr_inst);
void kvm_compute_layout(void);
void kvm_apply_hyp_relocations(void);
void kvm_apply_hyp_module_relocations(void *mod_start, void *hyp_va,
kvm_nvhe_reloc_t *begin,
kvm_nvhe_reloc_t *end);
#define __hyp_pa(x) (((phys_addr_t)(x)) + hyp_physvirt_offset)

68
arch/arm64/include/asm/kvm_pkvm_module.h
View File

@@ -14,6 +14,7 @@ enum pkvm_psci_notification {
PKVM_PSCI_CPU_ENTRY,
};
#ifdef CONFIG_MODULES
struct pkvm_module_ops {
int (*create_private_mapping)(phys_addr_t phys, size_t size,
enum kvm_pgtable_prot prot,
@@ -41,28 +42,24 @@ struct pkvm_module_ops {
unsigned long (*kern_hyp_va)(unsigned long x);
};
struct pkvm_module_section {
void *start;
void *end;
};
typedef s32 kvm_nvhe_reloc_t;
struct pkvm_el2_module {
struct pkvm_module_section text;
struct pkvm_module_section bss;
struct pkvm_module_section rodata;
struct pkvm_module_section data;
kvm_nvhe_reloc_t *relocs;
unsigned int nr_relocs;
int (*init)(const struct pkvm_module_ops *ops);
};
int __pkvm_load_el2_module(struct pkvm_el2_module *mod, struct module *this,
unsigned long *token);
int __pkvm_load_el2_module(struct module *this, unsigned long *token);
int __pkvm_register_el2_call(dyn_hcall_t hfn, unsigned long token,
unsigned long hyp_text_kern_va);
#else
static inline int __pkvm_load_el2_module(struct module *this,
unsigned long *token)
{
return -ENOSYS;
}
static inline int __pkvm_register_el2_call(dyn_hcall_t hfn, unsigned long token,
unsigned long hyp_text_kern_va)
{
return -ENOSYS;
}
#endif /* CONFIG_MODULES */
#ifdef MODULE
/*
* function_nocfi() does not work with function pointers, hence the macro in
@@ -70,39 +67,14 @@ int __pkvm_register_el2_call(dyn_hcall_t hfn, unsigned long token,
*/
#define pkvm_load_el2_module(init_fn, token) \
({ \
extern char __kvm_nvhe___hypmod_text_start[]; \
extern char __kvm_nvhe___hypmod_text_end[]; \
extern char __kvm_nvhe___hypmod_bss_start[]; \
extern char __kvm_nvhe___hypmod_bss_end[]; \
extern char __kvm_nvhe___hypmod_rodata_start[]; \
extern char __kvm_nvhe___hypmod_rodata_end[]; \
extern char __kvm_nvhe___hypmod_data_start[]; \
extern char __kvm_nvhe___hypmod_data_end[]; \
extern char __kvm_nvhe___hyprel_start[]; \
extern char __kvm_nvhe___hyprel_end[]; \
struct pkvm_el2_module mod; \
\
mod.text.start = __kvm_nvhe___hypmod_text_start; \
mod.text.end = __kvm_nvhe___hypmod_text_end; \
mod.bss.start = __kvm_nvhe___hypmod_bss_start; \
mod.bss.end = __kvm_nvhe___hypmod_bss_end; \
mod.rodata.start = __kvm_nvhe___hypmod_rodata_start; \
mod.rodata.end = __kvm_nvhe___hypmod_rodata_end; \
mod.data.start = __kvm_nvhe___hypmod_data_start; \
mod.data.end = __kvm_nvhe___hypmod_data_end; \
mod.relocs = (kvm_nvhe_reloc_t *)__kvm_nvhe___hyprel_start; \
mod.nr_relocs = (__kvm_nvhe___hyprel_end - __kvm_nvhe___hyprel_start) / \
sizeof(*mod.relocs); \
mod.init = function_nocfi(init_fn); \
\
__pkvm_load_el2_module(&mod, THIS_MODULE, token); \
THIS_MODULE->arch.hyp.init = function_nocfi(init_fn); \
__pkvm_load_el2_module(THIS_MODULE, token); \
})
#define pkvm_register_el2_mod_call(hfn, token) \
({ \
extern char __kvm_nvhe___hypmod_text_start[]; \
unsigned long hyp_text_kern_va = \
(unsigned long)__kvm_nvhe___hypmod_text_start; \
unsigned long hyp_text_kern_va; \
hyp_text_kern_va = THIS_MODULE->arch.hyp.text.start; \
__pkvm_register_el2_call(function_nocfi(hfn), token, \
hyp_text_kern_va); \
})

48
arch/arm64/include/asm/module.h
View File

@@ -14,12 +14,50 @@ struct mod_plt_sec {
int plt_max_entries;
};
struct mod_arch_specific {
struct mod_plt_sec core;
struct mod_plt_sec init;
/* for CONFIG_DYNAMIC_FTRACE */
#define ARM64_MODULE_PLTS_ARCHDATA \
struct mod_plt_sec core; \
struct mod_plt_sec init; \
\
/* for CONFIG_DYNAMIC_FTRACE */ \
struct plt_entry *ftrace_trampolines;
#else
#define ARM64_MODULE_PLTS_ARCHDATA
#endif
#ifdef CONFIG_KVM
struct pkvm_module_section {
void *start;
void *end;
};
typedef s32 kvm_nvhe_reloc_t;
struct pkvm_module_ops;
struct pkvm_el2_module {
struct pkvm_module_section text;
struct pkvm_module_section bss;
struct pkvm_module_section rodata;
struct pkvm_module_section data;
kvm_nvhe_reloc_t *relocs;
unsigned int nr_relocs;
int (*init)(const struct pkvm_module_ops *ops);
};
void kvm_apply_hyp_module_relocations(void *mod_start, void *hyp_va,
kvm_nvhe_reloc_t *begin,
kvm_nvhe_reloc_t *end);
#define ARM64_MODULE_KVM_ARCHDATA \
/* For pKVM hypervisor modules */ \
struct pkvm_el2_module hyp;
#else
#define ARM64_MODULE_KVM_ARCHDATA
#endif
#ifdef CONFIG_HAVE_MOD_ARCH_SPECIFIC
struct mod_arch_specific {
ARM64_MODULE_PLTS_ARCHDATA
ARM64_MODULE_KVM_ARCHDATA
};
#endif

60
arch/arm64/kernel/module.c
View File

@@ -520,14 +520,72 @@ static int module_init_ftrace_plt(const Elf_Ehdr *hdr,
return 0;
}
static int module_init_hyp(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs,
struct module *mod)
{
#ifdef CONFIG_KVM
const Elf_Shdr *s;
s = find_section(hdr, sechdrs, ".hyp.text");
if (!s)
return -ENOEXEC;
mod->arch.hyp.text = (struct pkvm_module_section) {
.start = (void *)s->sh_addr,
.end = (void *)s->sh_addr + s->sh_size,
};
s = find_section(hdr, sechdrs, ".hyp.bss");
if (!s)
return -ENOEXEC;
mod->arch.hyp.bss = (struct pkvm_module_section) {
.start = (void *)s->sh_addr,
.end = (void *)s->sh_addr + s->sh_size,
};
s = find_section(hdr, sechdrs, ".hyp.rodata");
if (!s)
return -ENOEXEC;
mod->arch.hyp.rodata = (struct pkvm_module_section) {
.start = (void *)s->sh_addr,
.end = (void *)s->sh_addr + s->sh_size,
};
s = find_section(hdr, sechdrs, ".hyp.data");
if (!s)
return -ENOEXEC;
mod->arch.hyp.data = (struct pkvm_module_section) {
.start = (void *)s->sh_addr,
.end = (void *)s->sh_addr + s->sh_size,
};
s = find_section(hdr, sechdrs, ".hyp.reloc");
if (!s)
return -ENOEXEC;
mod->arch.hyp.relocs = (void *)s->sh_addr;
mod->arch.hyp.nr_relocs = s->sh_size / sizeof(mod->arch.hyp.relocs);
#endif
return 0;
}
int module_finalize(const Elf_Ehdr *hdr,
const Elf_Shdr *sechdrs,
struct module *me)
{
int err;
const Elf_Shdr *s;
s = find_section(hdr, sechdrs, ".altinstructions");
if (s)
apply_alternatives_module((void *)s->sh_addr, s->sh_size);
return module_init_ftrace_plt(hdr, sechdrs, me);
err = module_init_ftrace_plt(hdr, sechdrs, me);
if (err)
return err;
return module_init_hyp(hdr, sechdrs, me);
}

13
arch/arm64/kvm/hyp/nvhe/module.lds.S
View File

@@ -6,32 +6,21 @@
SECTIONS {
.hyp.text : {
HYP_SECTION_SYMBOL_NAME(.text) = .;
__hypmod_text_start = .;
*(.text .text.*)
__hypmod_text_end = .;
}
.hyp.bss : {
HYP_SECTION_SYMBOL_NAME(.bss) = .;
__hypmod_bss_start = .;
*(.bss .bss.*)
FILL(0)
__hypmod_bss_end = .;
}
.hyp.rodata : {
HYP_SECTION_SYMBOL_NAME(.rodata) = .;
__hypmod_rodata_start = .;
*(.rodata .rodata.* .note.gnu.property)
BYTE(0)
__hypmod_rodata_end = .;
*(.rodata .rodata.*)
}
.hyp.data : {
HYP_SECTION_SYMBOL_NAME(.data) = .;
__hypmod_data_start = .;
*(.data .data.*)
BYTE(0)
__hypmod_data_end = .;
}
}

2
arch/arm64/kvm/hyp/nvhe/psci-relay.c
View File

@@ -31,10 +31,12 @@ static void pkvm_psci_notify(enum pkvm_psci_notification notif, struct kvm_cpu_c
pkvm_psci_notifier(notif, host_ctxt);
}
#ifdef CONFIG_MODULES
int __pkvm_register_psci_notifier(void (*cb)(enum pkvm_psci_notification, struct kvm_cpu_context *))
{
return cmpxchg(&pkvm_psci_notifier, NULL, cb) ? -EBUSY : 0;
}
#endif
#define INVALID_CPU_ID UINT_MAX

8
arch/arm64/kvm/pkvm.c
View File

@@ -507,7 +507,6 @@ static int __init early_pkvm_enable_modules(char *arg)
return 0;
}
early_param("kvm-arm.protected_modules", early_pkvm_enable_modules);
#endif
struct pkvm_mod_sec_mapping {
struct pkvm_module_section *sec;
@@ -584,9 +583,9 @@ static int __pkvm_cmp_mod_sec(const void *p1, const void *p2)
return s1->sec->start < s2->sec->start ? -1 : s1->sec->start > s2->sec->start;
}
int __pkvm_load_el2_module(struct pkvm_el2_module *mod, struct module *this,
unsigned long *token)
int __pkvm_load_el2_module(struct module *this, unsigned long *token)
{
struct pkvm_el2_module *mod = &this->arch.hyp;
struct pkvm_mod_sec_mapping secs_map[] = {
{ &mod->text, KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_X },
{ &mod->bss, KVM_PGTABLE_PROT_R | KVM_PGTABLE_PROT_W },
@@ -616,7 +615,7 @@ int __pkvm_load_el2_module(struct pkvm_el2_module *mod, struct module *this,
sort(secs_map, ARRAY_SIZE(secs_map), sizeof(secs_map[0]), __pkvm_cmp_mod_sec, NULL);
start = secs_map[0].sec->start;
end = secs_map[ARRAY_SIZE(secs_map) - 1].sec->end;
size = PAGE_ALIGN(end - start);
size = end - start;
hyp_va = (void *)kvm_call_hyp_nvhe(__pkvm_alloc_module_va, size >> PAGE_SHIFT);
if (!hyp_va) {
@@ -670,3 +669,4 @@ int __pkvm_register_el2_call(dyn_hcall_t hfn, unsigned long token,
return ret;
}
EXPORT_SYMBOL_GPL(__pkvm_register_el2_call);
#endif /* CONFIG_MODULES */