diff options
author | Ard Biesheuvel <ard.biesheuvel@linaro.org> | 2017-11-20 20:41:29 +0300 |
---|---|---|
committer | Will Deacon <will.deacon@arm.com> | 2017-12-01 15:30:21 +0300 |
commit | 7e8b9c1d2e2f5f45db7d40b50d14f606097c25de (patch) | |
tree | bbce43dfb8ebcfc44fcfb837363205628a608592 /arch | |
parent | f81a348728ec5ac43f3bbcf81c97d52baba253f7 (diff) | |
download | linux-7e8b9c1d2e2f5f45db7d40b50d14f606097c25de.tar.xz |
arm64: module-plts: factor out PLT generation code for ftrace
To allow the ftrace trampoline code to reuse the PLT entry routines,
factor it out and move it into asm/module.h.
Cc: <stable@vger.kernel.org>
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/arm64/include/asm/module.h | 44 | ||||
-rw-r--r-- | arch/arm64/kernel/module-plts.c | 38 |
2 files changed, 46 insertions, 36 deletions
diff --git a/arch/arm64/include/asm/module.h b/arch/arm64/include/asm/module.h index 19bd97671bb8..11d4aaee82e1 100644 --- a/arch/arm64/include/asm/module.h +++ b/arch/arm64/include/asm/module.h @@ -45,4 +45,48 @@ extern u64 module_alloc_base; #define module_alloc_base ((u64)_etext - MODULES_VSIZE) #endif +struct plt_entry { + /* + * A program that conforms to the AArch64 Procedure Call Standard + * (AAPCS64) must assume that a veneer that alters IP0 (x16) and/or + * IP1 (x17) may be inserted at any branch instruction that is + * exposed to a relocation that supports long branches. Since that + * is exactly what we are dealing with here, we are free to use x16 + * as a scratch register in the PLT veneers. + */ + __le32 mov0; /* movn x16, #0x.... */ + __le32 mov1; /* movk x16, #0x...., lsl #16 */ + __le32 mov2; /* movk x16, #0x...., lsl #32 */ + __le32 br; /* br x16 */ +}; + +static inline struct plt_entry get_plt_entry(u64 val) +{ + /* + * MOVK/MOVN/MOVZ opcode: + * +--------+------------+--------+-----------+-------------+---------+ + * | sf[31] | opc[30:29] | 100101 | hw[22:21] | imm16[20:5] | Rd[4:0] | + * +--------+------------+--------+-----------+-------------+---------+ + * + * Rd := 0x10 (x16) + * hw := 0b00 (no shift), 0b01 (lsl #16), 0b10 (lsl #32) + * opc := 0b11 (MOVK), 0b00 (MOVN), 0b10 (MOVZ) + * sf := 1 (64-bit variant) + */ + return (struct plt_entry){ + cpu_to_le32(0x92800010 | (((~val ) & 0xffff)) << 5), + cpu_to_le32(0xf2a00010 | ((( val >> 16) & 0xffff)) << 5), + cpu_to_le32(0xf2c00010 | ((( val >> 32) & 0xffff)) << 5), + cpu_to_le32(0xd61f0200) + }; +} + +static inline bool plt_entries_equal(const struct plt_entry *a, + const struct plt_entry *b) +{ + return a->mov0 == b->mov0 && + a->mov1 == b->mov1 && + a->mov2 == b->mov2; +} + #endif /* __ASM_MODULE_H */ diff --git a/arch/arm64/kernel/module-plts.c b/arch/arm64/kernel/module-plts.c index d05dbe658409..ebff6c155cac 100644 --- a/arch/arm64/kernel/module-plts.c +++ b/arch/arm64/kernel/module-plts.c @@ -11,21 +11,6 @@ #include <linux/module.h> #include <linux/sort.h> -struct plt_entry { - /* - * A program that conforms to the AArch64 Procedure Call Standard - * (AAPCS64) must assume that a veneer that alters IP0 (x16) and/or - * IP1 (x17) may be inserted at any branch instruction that is - * exposed to a relocation that supports long branches. Since that - * is exactly what we are dealing with here, we are free to use x16 - * as a scratch register in the PLT veneers. - */ - __le32 mov0; /* movn x16, #0x.... */ - __le32 mov1; /* movk x16, #0x...., lsl #16 */ - __le32 mov2; /* movk x16, #0x...., lsl #32 */ - __le32 br; /* br x16 */ -}; - static bool in_init(const struct module *mod, void *loc) { return (u64)loc - (u64)mod->init_layout.base < mod->init_layout.size; @@ -40,33 +25,14 @@ u64 module_emit_plt_entry(struct module *mod, void *loc, const Elf64_Rela *rela, int i = pltsec->plt_num_entries; u64 val = sym->st_value + rela->r_addend; - /* - * MOVK/MOVN/MOVZ opcode: - * +--------+------------+--------+-----------+-------------+---------+ - * | sf[31] | opc[30:29] | 100101 | hw[22:21] | imm16[20:5] | Rd[4:0] | - * +--------+------------+--------+-----------+-------------+---------+ - * - * Rd := 0x10 (x16) - * hw := 0b00 (no shift), 0b01 (lsl #16), 0b10 (lsl #32) - * opc := 0b11 (MOVK), 0b00 (MOVN), 0b10 (MOVZ) - * sf := 1 (64-bit variant) - */ - plt[i] = (struct plt_entry){ - cpu_to_le32(0x92800010 | (((~val ) & 0xffff)) << 5), - cpu_to_le32(0xf2a00010 | ((( val >> 16) & 0xffff)) << 5), - cpu_to_le32(0xf2c00010 | ((( val >> 32) & 0xffff)) << 5), - cpu_to_le32(0xd61f0200) - }; + plt[i] = get_plt_entry(val); /* * Check if the entry we just created is a duplicate. Given that the * relocations are sorted, this will be the last entry we allocated. * (if one exists). */ - if (i > 0 && - plt[i].mov0 == plt[i - 1].mov0 && - plt[i].mov1 == plt[i - 1].mov1 && - plt[i].mov2 == plt[i - 1].mov2) + if (i > 0 && plt_entries_equal(plt + i, plt + i - 1)) return (u64)&plt[i - 1]; pltsec->plt_num_entries++; |