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This commit adds a new port to libpulp: Powerpc64le. Signed-off-by: gbelinassi <[email protected]>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,34 @@ | ||
| #ifndef _ARCH_PPC64LE_H | ||
| #define _ARCH_PPC64LE_H | ||
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| /** Offset of TLS pointer. */ | ||
| #define TLS_DTV_OFFSET 0x8000 | ||
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| /** Struct used to store the registers in memory. */ | ||
| typedef struct pt_regs registers_t; | ||
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| /** Register in which the function stores the return value. */ | ||
| #define FUNCTION_RETURN_REG(reg) ((reg).gpr[3]) | ||
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| /** Register which acts as a program counter. */ | ||
| #define PROGRAM_COUNTER_REG(reg) ((reg).nip) | ||
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| /** Register which acts as top of stack. */ | ||
| #define STACK_TOP_REG(reg) ((reg).gpr[1]) | ||
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| /** Set the GLOBAL ENTRYPOINT REGISTER, which in power is r12. */ | ||
| #define SET_GLOBAL_ENTRYPOINT_REG(reg, val) (reg).gpr[12] = (val) | ||
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| /* Program load bias, which can be recovered by running `ld --verbose`. */ | ||
| #define EXECUTABLE_START 0x10000000UL | ||
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| /* The Red zone. */ | ||
| #define RED_ZONE_LEN 512 | ||
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| /** | ||
| * Number of bytes that the kernel subtracts from the program counter, | ||
| * when an ongoing syscall gets interrupted and must be restarted. | ||
| */ | ||
| #define RESTART_SYSCALL_SIZE 0 | ||
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| #endif |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,222 @@ | ||
| /* | ||
| * libpulp - User-space Livepatching Library | ||
| * | ||
| * Copyright (C) 2017-2023 SUSE Software Solutions GmbH | ||
| * | ||
| * This file is part of libpulp. | ||
| * | ||
| * libpulp is free software; you can redistribute it and/or | ||
| * modify it under the terms of the GNU Lesser General Public | ||
| * License as published by the Free Software Foundation; either | ||
| * version 2.1 of the License, or (at your option) any later version. | ||
| * | ||
| * libpulp is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | ||
| * Lesser General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License | ||
| * along with libpulp. If not, see <http://www.gnu.org/licenses/>. | ||
| */ | ||
|
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| #define _GNU_SOURCE | ||
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| #include <stddef.h> | ||
| #include <string.h> | ||
| #include <limits.h> | ||
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| #include "config.h" | ||
| #include "error.h" | ||
| #include "insn_queue_lib.h" | ||
| #include "msg_queue.h" | ||
| #include "ulp.h" | ||
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| /* clang-format off */ | ||
|
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| /** Size of each instructions, in bytes. */ | ||
| #define INSN_SIZE 4 | ||
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| static unsigned char ulp_prologue[INSN_SIZE * PRE_NOPS_LEN] = { | ||
| 0x22, 0x11, 0x80, 0x3d, // lis r12,0x1122 | ||
| 0xa6, 0x02, 0x08, 0x7c, // mflr r0 | ||
| 0x44, 0x33, 0x8c, 0x61, // ori r12,r12,0x3344 | ||
| 0xc6, 0x07, 0x8c, 0x79, // sldi r12,r12,32 | ||
| 0x66, 0x55, 0x8c, 0x65, // oris r12,r12,0x5566 | ||
| 0x10, 0x00, 0x01, 0xf8, // std r0,16(r1) | ||
| 0xe1, 0xff, 0x21, 0xf8, // stdu r1,-32(r1) | ||
| 0x88, 0x77, 0x8c, 0x61, // ori r12,r12,0x7788 | ||
| 0x18, 0x00, 0x41, 0xf8, // std r2,24(r1) | ||
| 0xa6, 0x03, 0x89, 0x7d, // mtctr r12 | ||
| 0x21, 0x04, 0x80, 0x4e, // bctrl | ||
| 0x18, 0x00, 0x41, 0xe8, // ld r2,24(r1) | ||
| 0x20, 0x00, 0x21, 0x38, // addi r1,r1,32 | ||
| 0x10, 0x00, 0x01, 0xe8, // ld r0,16(r1) | ||
| 0xa6, 0x03, 0x08, 0x7c, // mtlr r0 | ||
| 0x20, 0x00, 0x80, 0x4e, // blr | ||
| }; | ||
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| /** The NOP instruction. */ | ||
| static const unsigned char gNop[] = { 0x00, 0x00, 0x00, 0x60 }; | ||
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| /** Generate a branch (b) instruction according to offset. */ | ||
| static uint32_t | ||
| generate_branch_to_prologue(int32_t offset) | ||
| { | ||
| return (offset & 0x00FFFFFF) | (0x4B << 24); | ||
| } | ||
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| #define WITH_OFFSET(x) (-(INSN_SIZE * PRE_NOPS_LEN + (offset))) | ||
| #define WITHOUT_OFFSET WITH_OFFSET(0) | ||
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| /* clang-format on */ | ||
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| /** @brief Copy the ulp prologue layout into the function to be patched's | ||
| * prologue | ||
| * | ||
| * This function copies the new code prologue into the old function prologue | ||
| * in order to redirect the execution to the new function. | ||
| * | ||
| */ | ||
| static void | ||
| ulp_patch_prologue_layout(void *old_fentry, void *new_fentry, const unsigned char *prologue, int len) | ||
| { | ||
| (void) len; | ||
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| /* Create a copy of the prologue. */ | ||
| unsigned char prolog[INSN_SIZE*PRE_NOPS_LEN]; | ||
| _Static_assert(sizeof(prolog) == sizeof(ulp_prologue), | ||
| "Prologue sizes do not match"); | ||
| memcpy(prolog, prologue, sizeof(prolog)); | ||
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| unsigned char new_fentry_bytes[sizeof(void*)]; | ||
| memcpy(new_fentry_bytes, &new_fentry, sizeof(new_fentry_bytes)); | ||
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| /* Patch the code with the address of the function we want to be redirected. */ | ||
| prolog[0] = new_fentry_bytes[6]; | ||
| prolog[1] = new_fentry_bytes[7]; | ||
| prolog[8] = new_fentry_bytes[4]; | ||
| prolog[9] = new_fentry_bytes[5]; | ||
| prolog[16] = new_fentry_bytes[2]; | ||
| prolog[17] = new_fentry_bytes[3]; | ||
| prolog[28] = new_fentry_bytes[0]; | ||
| prolog[29] = new_fentry_bytes[1]; | ||
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| /* Point to the prologue. */ | ||
| char *fentry_prologue = old_fentry - INSN_SIZE * PRE_NOPS_LEN; | ||
| memwrite(fentry_prologue, prolog, INSN_SIZE * PRE_NOPS_LEN); | ||
| } | ||
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| /** @brief Get the offset of the NOP instruction. | ||
| * | ||
| * Some function do not have a global entry point prologue, that means | ||
| * the NOP instruction is placed at the same address as the calling point. | ||
| * We have to figure out which case we are handling. | ||
| */ | ||
| static int | ||
| get_branch_offset(void *fentry) | ||
| { | ||
| int valid_offsets[] = { | ||
| 0, // NOP located at the calling point. | ||
| 8, // func with global entry point, NOP is located 8 bytes after it. | ||
| }; | ||
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| for (unsigned i = 0; i < ARRAY_LENGTH(valid_offsets); i++) { | ||
| int offset = valid_offsets[i]; | ||
| void *fpos = (void *) ((char *)fentry + offset); | ||
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| /* Generate a branch instruction to the begining of the NOP prologue. */ | ||
| uint32_t branch = generate_branch_to_prologue(WITH_OFFSET(offset)); | ||
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| /* There are two cases we must check: | ||
| - Function not livepatched: have a NOP insn here. | ||
| - Function is livepatched: have a B (branch) insn here. */ | ||
| if (memcmp(fpos, gNop, sizeof(gNop)) == 0 || | ||
| memcmp(fpos, &branch, sizeof(branch)) == 0) { | ||
| return offset; | ||
| } | ||
| } | ||
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| /* Not valid. */ | ||
| return -INT_MAX; | ||
| } | ||
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| /** @brief skip the ulp prologue. | ||
| * | ||
| * When a function gets live patch, the nops at its entry point get replaced | ||
| * with a backwards-jump to a small segment of code that redirects execution to | ||
| * the new version of the function. However, when all live patches to said | ||
| * function are deactivated (because the live patches have been reversed), the | ||
| * need for the backwards-jump is gone. | ||
| * | ||
| * The following function replaces the backwards-jump with nops, thus making | ||
| * the target function look like it did at the beginning of execution, i.e. | ||
| * without live patches. | ||
| * | ||
| * @param fentry Address to write the prologue to. | ||
| */ | ||
| static int | ||
| ulp_skip_prologue(void *fentry) | ||
| { | ||
| int offset = get_branch_offset(fentry); | ||
| if (offset < 0) { | ||
| return ENOPATCHABLE; | ||
| } | ||
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| unsigned char *dst = (unsigned char *)fentry + get_branch_offset(fentry); | ||
| memwrite(dst, gNop, sizeof(gNop)); | ||
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| return 0; | ||
| } | ||
|
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| /** @brief Insert the backwards jump to the NOP prologue. | ||
| * | ||
| * When a function gets live patch, the nops at its entry point get replaced | ||
| * with a backwards-jump to a small segment of code that redirects execution to | ||
| * the new version of the function. This function does exactly this. | ||
| * | ||
| * @param fentry Address to write the prologue to. | ||
| */ | ||
| static int | ||
| ulp_patch_addr_trampoline(void *old_fentry) | ||
| { | ||
| int offset = get_branch_offset(old_fentry); | ||
| if (offset < 0) { | ||
| return ENOPATCHABLE; | ||
| } | ||
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| uint32_t branch = generate_branch_to_prologue(WITH_OFFSET(offset)); | ||
| char *dst = (char *)old_fentry + offset; | ||
| memwrite(dst, &branch, sizeof(branch)); | ||
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| return 0; | ||
| } | ||
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| /** @brief Actually patch the old function with the new function | ||
| * | ||
| * This function will finally patch the old function pointed by `old_faddr` | ||
| * with the one pointed by `new_faddr`, replacing the ulp NOP prologue with | ||
| * the intended content to redirect to the new function. | ||
| * | ||
| * @param old_faddr Address of the old function. | ||
| * @param new_faddr Address of the new function. | ||
| * @param enable False to disable the redirection to the new function. | ||
| * | ||
| * @return 0 if success, error code otherwise. | ||
| */ | ||
| int | ||
| ulp_patch_addr(void *old_faddr, void *new_faddr, int enable) | ||
| { | ||
| unsigned char *dst = (unsigned char *) old_faddr; | ||
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| int ret = 0; | ||
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| if (enable) { | ||
| ulp_patch_prologue_layout(dst, new_faddr, ulp_prologue, 4*ULP_NOPS_LEN); | ||
| ret = ulp_patch_addr_trampoline(dst); | ||
| } else { | ||
| ret = ulp_skip_prologue(dst); | ||
| } | ||
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| return ret; | ||
| } |
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