lwn.git/arch/powerpc/include/asm/code-patching.h, branch v5.2-rc7

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation either version 2 of the license or at your option any later version extracted by the scancode license scanner the SPDX license identifier GPL-2.0-or-later has been chosen to replace the boilerplate/reference in 3029 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de Signed-off-by: Greg Kroah-Hartman

powerpc: add modify_instruction() and modify_instruction_site()

2018-12-19T07:56:32+00:00

Add two helpers to avoid hardcoding of instructions modifications. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman

powerpc: simplify patch_instruction_site() and patch_branch_site()

2018-12-19T07:56:32+00:00

Using patch_site_addr() helper, patch_instruction_site() and patch_branch_site() can be simplified and inlined. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman

powerpc/code-patching: Add a helper to get the address of a patch_site

2018-10-26T10:58:58+00:00

This patch adds a helper to get the address of a patch_site. Signed-off-by: Christophe Leroy [mpe: Call it "patch site" addr] Signed-off-by: Michael Ellerman

powerpc/asm: Add a patch_site macro & helpers for patching instructions

2018-08-07T14:32:25+00:00

Add a macro and some helper C functions for patching single asm instructions. The gas macro means we can do something like: 1: nop patch_site 1b, patch__foo Which is less visually distracting than defining a GLOBAL symbol at 1, and also doesn't pollute the symbol table which can confuse eg. perf. These are obviously similar to our existing feature sections, but are not automatically patched based on CPU/MMU features, rather they are designed to be manually patched by C code at some arbitrary point. Signed-off-by: Michael Ellerman

powerpc: move ASM_CONST and stringify_in_c() into asm-const.h

2018-07-30T12:48:16+00:00

This patch moves ASM_CONST() and stringify_in_c() into dedicated asm-const.h, then cleans all related inclusions. Signed-off-by: Christophe Leroy [mpe: asm-compat.h should include asm-const.h] Signed-off-by: Michael Ellerman

powerpc/lib/feature-fixups: use raw_patch_instruction()

2018-01-21T04:06:25+00:00

feature fixups need to use patch_instruction() early in the boot, even before the code is relocated to its final address, requiring patch_instruction() to use PTRRELOC() in order to address data. But feature fixups applies on code before it is set to read only, even for modules. Therefore, feature fixups can use raw_patch_instruction() instead. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman

powerpc/modules: Don't try to restore r2 after a sibling call

2017-12-11T02:03:29+00:00

When attempting to load a livepatch module, I got the following error: module_64: patch_module: Expect noop after relocate, got 3c820000 The error was triggered by the following code in unregister_netdevice_queue(): 14c: 00 00 00 48 b 14c 14c: R_PPC64_REL24 net_set_todo 150: 00 00 82 3c addis r4,r2,0 GCC didn't insert a nop after the branch to net_set_todo() because it's a sibling call, so it never returns. The nop isn't needed after the branch in that case. Signed-off-by: Josh Poimboeuf Acked-by: Naveen N. Rao Reviewed-and-tested-by: Kamalesh Babulal Signed-off-by: Michael Ellerman

Revert "powerpc64/elfv1: Only dereference function descriptor for non-text symbols"

2017-11-01T04:50:12+00:00

This reverts commit 83e840c770f2c5 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols"). Chandan reported that on newer kernels, trying to enable function_graph tracer on ppc64 (BE) locks up the system with the following trace: Unable to handle kernel paging request for data at address 0x600000002fa30010 Faulting instruction address: 0xc0000000001f1300 Thread overran stack, or stack corrupted Oops: Kernel access of bad area, sig: 11 [#1] BE SMP NR_CPUS=2048 DEBUG_PAGEALLOC NUMA pSeries Modules linked in: CPU: 1 PID: 6586 Comm: bash Not tainted 4.14.0-rc3-00162-g6e51f1f-dirty #20 task: c000000625c07200 task.stack: c000000625c07310 NIP: c0000000001f1300 LR: c000000000121cac CTR: c000000000061af8 REGS: c000000625c088c0 TRAP: 0380 Not tainted (4.14.0-rc3-00162-g6e51f1f-dirty) MSR: 8000000000001032 CR: 28002848 XER: 00000000 CFAR: c0000000001f1320 SOFTE: 0 ... NIP [c0000000001f1300] .__is_insn_slot_addr+0x30/0x90 LR [c000000000121cac] .kernel_text_address+0x18c/0x1c0 Call Trace: [c000000625c08b40] [c0000000001bd040] .is_module_text_address+0x20/0x40 (unreliable) [c000000625c08bc0] [c000000000121cac] .kernel_text_address+0x18c/0x1c0 [c000000625c08c50] [c000000000061960] .prepare_ftrace_return+0x50/0x130 [c000000625c08cf0] [c000000000061b10] .ftrace_graph_caller+0x14/0x34 [c000000625c08d60] [c000000000121b40] .kernel_text_address+0x20/0x1c0 [c000000625c08df0] [c000000000061960] .prepare_ftrace_return+0x50/0x130 ... [c000000625c0ab30] [c000000000061960] .prepare_ftrace_return+0x50/0x130 [c000000625c0abd0] [c000000000061b10] .ftrace_graph_caller+0x14/0x34 [c000000625c0ac40] [c000000000121b40] .kernel_text_address+0x20/0x1c0 [c000000625c0acd0] [c000000000061960] .prepare_ftrace_return+0x50/0x130 [c000000625c0ad70] [c000000000061b10] .ftrace_graph_caller+0x14/0x34 [c000000625c0ade0] [c000000000121b40] .kernel_text_address+0x20/0x1c0 This is because ftrace is using ppc_function_entry() for obtaining the address of return_to_handler() in prepare_ftrace_return(). The call to kernel_text_address() itself gets traced and we end up in a recursive loop. Fixes: 83e840c770f2 ("powerpc64/elfv1: Only dereference function descriptor for non-text symbols") Cc: stable@vger.kernel.org # v4.13+ Reported-by: Chandan Rajendra Signed-off-by: Naveen N. Rao Signed-off-by: Michael Ellerman

powerpc64/elfv1: Only dereference function descriptor for non-text symbols

2017-07-03T13:08:50+00:00

Currently, we assume that the function pointer we receive in ppc_function_entry() points to a function descriptor. However, this is not always the case. In particular, assembly symbols without the right annotation do not have an associated function descriptor. Some of these symbols are added to the kprobe blacklist using _ASM_NOKPROBE_SYMBOL(). When such addresses are subsequently processed through arch_deref_entry_point() in populate_kprobe_blacklist(), we see the below errors during bootup: [ 0.663963] Failed to find blacklist at 7d9b02a648029b6c [ 0.663970] Failed to find blacklist at a14d03d0394a0001 [ 0.663972] Failed to find blacklist at 7d5302a6f94d0388 [ 0.663973] Failed to find blacklist at 48027d11e8610178 [ 0.663974] Failed to find blacklist at f8010070f8410080 [ 0.663976] Failed to find blacklist at 386100704801f89d [ 0.663977] Failed to find blacklist at 7d5302a6f94d00b0 Fix this by checking if the function pointer we receive in ppc_function_entry() already points to kernel text. If so, we just return it as is. If not, we assume that this is a function descriptor and proceed to dereference it. Suggested-by: Nicholas Piggin Reviewed-by: Nicholas Piggin Signed-off-by: Naveen N. Rao Signed-off-by: Michael Ellerman