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Message-ID: <20250503112137.1962910-7-ardb+git@google.com> Date: Sat, 3 May 2025 13:21:40 +0200 From: Ard Biesheuvel <ardb+git@...gle.com> To: linux-arm-kernel@...ts.infradead.org Cc: linux-kernel@...r.kernel.org, will@...nel.org, catalin.marinas@....com, mark.rutland@....com, Ard Biesheuvel <ardb@...nel.org>, Yeoreum Yun <yeoreum.yun@....com> Subject: [PATCH 3/3] arm64/boot: Disallow BSS exports to startup code From: Ard Biesheuvel <ardb@...nel.org> BSS might be uninitialized when entering the startup code, so forbid the use of any variables that live after __bss_start in the linker map. Signed-off-by: Ard Biesheuvel <ardb@...nel.org> --- arch/arm64/kernel/image-vars.h | 66 +++++++++++--------- arch/arm64/kernel/vmlinux.lds.S | 2 + 2 files changed, 37 insertions(+), 31 deletions(-) diff --git a/arch/arm64/kernel/image-vars.h b/arch/arm64/kernel/image-vars.h index a0977f7cd3ec..a70244d1aa2a 100644 --- a/arch/arm64/kernel/image-vars.h +++ b/arch/arm64/kernel/image-vars.h @@ -10,6 +10,12 @@ #error This file should only be included in vmlinux.lds.S #endif +#define PI_EXPORT_SYM(sym) \ + __PI_EXPORT_SYM(sym, __pi_ ## sym, Cannot export BSS symbol sym to startup code) +#define __PI_EXPORT_SYM(sym, pisym, msg)\ + PROVIDE(pisym = sym); \ + ASSERT(sym < __bss_start, #msg) + PROVIDE(__efistub_primary_entry = primary_entry); /* @@ -36,39 +42,37 @@ PROVIDE(__pi___memcpy = __pi_memcpy); PROVIDE(__pi___memmove = __pi_memmove); PROVIDE(__pi___memset = __pi_memset); -PROVIDE(__pi_id_aa64isar1_override = id_aa64isar1_override); -PROVIDE(__pi_id_aa64isar2_override = id_aa64isar2_override); -PROVIDE(__pi_id_aa64mmfr0_override = id_aa64mmfr0_override); -PROVIDE(__pi_id_aa64mmfr1_override = id_aa64mmfr1_override); -PROVIDE(__pi_id_aa64mmfr2_override = id_aa64mmfr2_override); -PROVIDE(__pi_id_aa64pfr0_override = id_aa64pfr0_override); -PROVIDE(__pi_id_aa64pfr1_override = id_aa64pfr1_override); -PROVIDE(__pi_id_aa64smfr0_override = id_aa64smfr0_override); -PROVIDE(__pi_id_aa64zfr0_override = id_aa64zfr0_override); -PROVIDE(__pi_arm64_sw_feature_override = arm64_sw_feature_override); -PROVIDE(__pi_arm64_use_ng_mappings = arm64_use_ng_mappings); +PI_EXPORT_SYM(id_aa64isar1_override); +PI_EXPORT_SYM(id_aa64isar2_override); +PI_EXPORT_SYM(id_aa64mmfr0_override); +PI_EXPORT_SYM(id_aa64mmfr1_override); +PI_EXPORT_SYM(id_aa64mmfr2_override); +PI_EXPORT_SYM(id_aa64pfr0_override); +PI_EXPORT_SYM(id_aa64pfr1_override); +PI_EXPORT_SYM(id_aa64smfr0_override); +PI_EXPORT_SYM(id_aa64zfr0_override); +PI_EXPORT_SYM(arm64_sw_feature_override); +PI_EXPORT_SYM(arm64_use_ng_mappings); #ifdef CONFIG_CAVIUM_ERRATUM_27456 -PROVIDE(__pi_cavium_erratum_27456_cpus = cavium_erratum_27456_cpus); -PROVIDE(__pi_is_midr_in_range_list = is_midr_in_range_list); +PI_EXPORT_SYM(cavium_erratum_27456_cpus); +PI_EXPORT_SYM(is_midr_in_range_list); #endif -PROVIDE(__pi__ctype = _ctype); -PROVIDE(__pi_memstart_offset_seed = memstart_offset_seed); - -PROVIDE(__pi_init_idmap_pg_dir = init_idmap_pg_dir); -PROVIDE(__pi_init_idmap_pg_end = init_idmap_pg_end); -PROVIDE(__pi_swapper_pg_dir = swapper_pg_dir); - -PROVIDE(__pi__text = _text); -PROVIDE(__pi__stext = _stext); -PROVIDE(__pi__etext = _etext); -PROVIDE(__pi___start_rodata = __start_rodata); -PROVIDE(__pi___inittext_begin = __inittext_begin); -PROVIDE(__pi___inittext_end = __inittext_end); -PROVIDE(__pi___initdata_begin = __initdata_begin); -PROVIDE(__pi___initdata_end = __initdata_end); -PROVIDE(__pi__data = _data); -PROVIDE(__pi___bss_start = __bss_start); -PROVIDE(__pi__end = _end); +PI_EXPORT_SYM(_ctype); +PI_EXPORT_SYM(memstart_offset_seed); + +PI_EXPORT_SYM(init_idmap_pg_dir); +PI_EXPORT_SYM(init_idmap_pg_end); +PI_EXPORT_SYM(swapper_pg_dir); + +PI_EXPORT_SYM(_text); +PI_EXPORT_SYM(_stext); +PI_EXPORT_SYM(_etext); +PI_EXPORT_SYM(__start_rodata); +PI_EXPORT_SYM(__inittext_begin); +PI_EXPORT_SYM(__inittext_end); +PI_EXPORT_SYM(__initdata_begin); +PI_EXPORT_SYM(__initdata_end); +PI_EXPORT_SYM(_data); #ifdef CONFIG_KVM diff --git a/arch/arm64/kernel/vmlinux.lds.S b/arch/arm64/kernel/vmlinux.lds.S index 73fa57f341b0..bd7626b8c7a3 100644 --- a/arch/arm64/kernel/vmlinux.lds.S +++ b/arch/arm64/kernel/vmlinux.lds.S @@ -319,6 +319,7 @@ SECTIONS /* start of zero-init region */ BSS_SECTION(SBSS_ALIGN, 0, 0) + __pi___bss_start = __bss_start; . = ALIGN(PAGE_SIZE); __pi_init_pg_dir = .; @@ -332,6 +333,7 @@ SECTIONS . = ALIGN(SEGMENT_ALIGN); __pecoff_data_size = ABSOLUTE(. - __initdata_begin); _end = .; + __pi__end = .; STABS_DEBUG DWARF_DEBUG -- 2.49.0.906.g1f30a19c02-goog
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