[PATCH stable 4.9 v3 0/4] ARM: ftrace MODULE_PLTS warning

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[PATCH v4.4 v4.9 v4.14] arm64:...

[PATCH 5.14 000/162] 5.14.9-rc1...

Florian Fainelli

27 Sep 2021 27 Sep '21

9:03 p.m.

This patch series is present in v5.14 and fixes warnings seen at insmod with FTRACE and MODULE_PLTS enabled on ARM/Linux.

Changes in v3:

- resolved build error with allmodconfig enabling CONFIG_OLD_MCOUNT

Changes in v2:

- included build fix without DYNAMIC_FTRACE - preserved Author's original name in 4.9 submission

Alex Sverdlin (4): ARM: 9077/1: PLT: Move struct plt_entries definition to header ARM: 9078/1: Add warn suppress parameter to arm_gen_branch_link() ARM: 9079/1: ftrace: Add MODULE_PLTS support ARM: 9098/1: ftrace: MODULE_PLT: Fix build problem without DYNAMIC_FTRACE

arch/arm/include/asm/ftrace.h | 3 +++ arch/arm/include/asm/insn.h | 8 +++--- arch/arm/include/asm/module.h | 10 +++++++ arch/arm/kernel/ftrace.c | 45 +++++++++++++++++++++++++++----- arch/arm/kernel/insn.c | 19 +++++++------- arch/arm/kernel/module-plts.c | 49 +++++++++++++++++++++++++++-------- 6 files changed, 103 insertions(+), 31 deletions(-)

-- 2.25.1

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Florian Fainelli

27 Sep 27 Sep

9:03 p.m.

New subject: [PATCH stable 4.9 v3 1/4] ARM: 9077/1: PLT: Move struct plt_entries definition to header

From: Alex Sverdlin alexander.sverdlin@nokia.com

commit 4e271701c17dee70c6e1351c4d7d42e70405c6a9 upstream

No functional change, later it will be re-used in several files.

Signed-off-by: Alexander Sverdlin alexander.sverdlin@nokia.com Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: Florian Fainelli f.fainelli@gmail.com --- arch/arm/include/asm/module.h | 9 +++++++++ arch/arm/kernel/module-plts.c | 9 --------- 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h index ed2319663a1e..2e9872a22359 100644 --- a/arch/arm/include/asm/module.h +++ b/arch/arm/include/asm/module.h @@ -18,6 +18,15 @@ enum { }; #endif

+#define PLT_ENT_STRIDE L1_CACHE_BYTES +#define PLT_ENT_COUNT (PLT_ENT_STRIDE / sizeof(u32)) +#define PLT_ENT_SIZE (sizeof(struct plt_entries) / PLT_ENT_COUNT) + +struct plt_entries { + u32 ldr[PLT_ENT_COUNT]; + u32 lit[PLT_ENT_COUNT]; +}; + struct mod_plt_sec { struct elf32_shdr *plt; int plt_count; diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c index 3d0c2e4dda1d..f272711c411f 100644 --- a/arch/arm/kernel/module-plts.c +++ b/arch/arm/kernel/module-plts.c @@ -14,10 +14,6 @@ #include <asm/cache.h> #include <asm/opcodes.h>

-#define PLT_ENT_STRIDE L1_CACHE_BYTES -#define PLT_ENT_COUNT (PLT_ENT_STRIDE / sizeof(u32)) -#define PLT_ENT_SIZE (sizeof(struct plt_entries) / PLT_ENT_COUNT) - #ifdef CONFIG_THUMB2_KERNEL #define PLT_ENT_LDR __opcode_to_mem_thumb32(0xf8dff000 | \ (PLT_ENT_STRIDE - 4)) @@ -26,11 +22,6 @@ (PLT_ENT_STRIDE - 8)) #endif

-struct plt_entries { - u32 ldr[PLT_ENT_COUNT]; - u32 lit[PLT_ENT_COUNT]; -}; - static bool in_init(const struct module *mod, unsigned long loc) { return loc - (u32)mod->init_layout.base < mod->init_layout.size;

-- 2.25.1

Florian Fainelli

9:03 p.m.

New subject: [PATCH stable 4.9 v3 2/4] ARM: 9078/1: Add warn suppress parameter to arm_gen_branch_link()

From: Alex Sverdlin alexander.sverdlin@nokia.com

commit 890cb057a46d323fd8c77ebecb6485476614cd21 upstream

Will be used in the following patch. No functional change.

Signed-off-by: Alexander Sverdlin alexander.sverdlin@nokia.com Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: Florian Fainelli f.fainelli@gmail.com --- arch/arm/include/asm/insn.h | 8 ++++---- arch/arm/kernel/ftrace.c | 2 +- arch/arm/kernel/insn.c | 19 ++++++++++--------- 3 files changed, 15 insertions(+), 14 deletions(-)

diff --git a/arch/arm/include/asm/insn.h b/arch/arm/include/asm/insn.h index e96065da4dae..0043bf609f27 100644 --- a/arch/arm/include/asm/insn.h +++ b/arch/arm/include/asm/insn.h @@ -12,18 +12,18 @@ arm_gen_nop(void) }

unsigned long -__arm_gen_branch(unsigned long pc, unsigned long addr, bool link); +__arm_gen_branch(unsigned long pc, unsigned long addr, bool link, bool warn);

static inline unsigned long arm_gen_branch(unsigned long pc, unsigned long addr) { - return __arm_gen_branch(pc, addr, false); + return __arm_gen_branch(pc, addr, false, true); }

static inline unsigned long -arm_gen_branch_link(unsigned long pc, unsigned long addr) +arm_gen_branch_link(unsigned long pc, unsigned long addr, bool warn) { - return __arm_gen_branch(pc, addr, true); + return __arm_gen_branch(pc, addr, true, warn); }

#endif diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index 414e60ed0257..a95bc0a02fd8 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -97,7 +97,7 @@ int ftrace_arch_code_modify_post_process(void)

static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr) { - return arm_gen_branch_link(pc, addr); + return arm_gen_branch_link(pc, addr, true); }

static int ftrace_modify_code(unsigned long pc, unsigned long old, diff --git a/arch/arm/kernel/insn.c b/arch/arm/kernel/insn.c index b760340b7014..eaded01b7edf 100644 --- a/arch/arm/kernel/insn.c +++ b/arch/arm/kernel/insn.c @@ -2,8 +2,9 @@ #include <linux/kernel.h> #include <asm/opcodes.h>

-static unsigned long -__arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link) +static unsigned long __arm_gen_branch_thumb2(unsigned long pc, + unsigned long addr, bool link, + bool warn) { unsigned long s, j1, j2, i1, i2, imm10, imm11; unsigned long first, second; @@ -11,7 +12,7 @@ __arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link)

offset = (long)addr - (long)(pc + 4); if (offset < -16777216 || offset > 16777214) { - WARN_ON_ONCE(1); + WARN_ON_ONCE(warn); return 0; }

@@ -32,8 +33,8 @@ __arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link) return __opcode_thumb32_compose(first, second); }

-static unsigned long -__arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link) +static unsigned long __arm_gen_branch_arm(unsigned long pc, unsigned long addr, + bool link, bool warn) { unsigned long opcode = 0xea000000; long offset; @@ -43,7 +44,7 @@ __arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link)

offset = (long)addr - (long)(pc + 8); if (unlikely(offset < -33554432 || offset > 33554428)) { - WARN_ON_ONCE(1); + WARN_ON_ONCE(warn); return 0; }

@@ -53,10 +54,10 @@ __arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link) }

unsigned long -__arm_gen_branch(unsigned long pc, unsigned long addr, bool link) +__arm_gen_branch(unsigned long pc, unsigned long addr, bool link, bool warn) { if (IS_ENABLED(CONFIG_THUMB2_KERNEL)) - return __arm_gen_branch_thumb2(pc, addr, link); + return __arm_gen_branch_thumb2(pc, addr, link, warn); else - return __arm_gen_branch_arm(pc, addr, link); + return __arm_gen_branch_arm(pc, addr, link, warn); }

-- 2.25.1

Florian Fainelli

9:03 p.m.

New subject: [PATCH stable 4.9 v3 3/4] ARM: 9079/1: ftrace: Add MODULE_PLTS support

From: Alex Sverdlin alexander.sverdlin@nokia.com

commit 79f32b221b18c15a98507b101ef4beb52444cc6f upstream

Teach ftrace_make_call() and ftrace_make_nop() about PLTs. Teach PLT code about FTRACE and all its callbacks. Otherwise the following might happen:

------------[ cut here ]------------ WARNING: CPU: 14 PID: 2265 at .../arch/arm/kernel/insn.c:14 __arm_gen_branch+0x83/0x8c() ... Hardware name: LSI Axxia AXM55XX [<c0314a49>] (unwind_backtrace) from [<c03115e9>] (show_stack+0x11/0x14) [<c03115e9>] (show_stack) from [<c0519f51>] (dump_stack+0x81/0xa8) [<c0519f51>] (dump_stack) from [<c032185d>] (warn_slowpath_common+0x69/0x90) [<c032185d>] (warn_slowpath_common) from [<c03218f3>] (warn_slowpath_null+0x17/0x1c) [<c03218f3>] (warn_slowpath_null) from [<c03143cf>] (__arm_gen_branch+0x83/0x8c) [<c03143cf>] (__arm_gen_branch) from [<c0314337>] (ftrace_make_nop+0xf/0x24) [<c0314337>] (ftrace_make_nop) from [<c038ebcb>] (ftrace_process_locs+0x27b/0x3e8) [<c038ebcb>] (ftrace_process_locs) from [<c0378d79>] (load_module+0x11e9/0x1a44) [<c0378d79>] (load_module) from [<c037974d>] (SyS_finit_module+0x59/0x84) [<c037974d>] (SyS_finit_module) from [<c030e981>] (ret_fast_syscall+0x1/0x18) ---[ end trace e1b64ced7a89adcc ]--- ------------[ cut here ]------------ WARNING: CPU: 14 PID: 2265 at .../kernel/trace/ftrace.c:1979 ftrace_bug+0x1b1/0x234() ... Hardware name: LSI Axxia AXM55XX [<c0314a49>] (unwind_backtrace) from [<c03115e9>] (show_stack+0x11/0x14) [<c03115e9>] (show_stack) from [<c0519f51>] (dump_stack+0x81/0xa8) [<c0519f51>] (dump_stack) from [<c032185d>] (warn_slowpath_common+0x69/0x90) [<c032185d>] (warn_slowpath_common) from [<c03218f3>] (warn_slowpath_null+0x17/0x1c) [<c03218f3>] (warn_slowpath_null) from [<c038e87d>] (ftrace_bug+0x1b1/0x234) [<c038e87d>] (ftrace_bug) from [<c038ebd5>] (ftrace_process_locs+0x285/0x3e8) [<c038ebd5>] (ftrace_process_locs) from [<c0378d79>] (load_module+0x11e9/0x1a44) [<c0378d79>] (load_module) from [<c037974d>] (SyS_finit_module+0x59/0x84) [<c037974d>] (SyS_finit_module) from [<c030e981>] (ret_fast_syscall+0x1/0x18) ---[ end trace e1b64ced7a89adcd ]--- ftrace failed to modify [<e9ef7006>] 0xe9ef7006 actual: 02:f0:3b:fa ftrace record flags: 0 (0) expected tramp: c0314265

Signed-off-by: Alexander Sverdlin alexander.sverdlin@nokia.com Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: Florian Fainelli f.fainelli@gmail.com --- arch/arm/include/asm/ftrace.h | 3 +++ arch/arm/include/asm/module.h | 1 + arch/arm/kernel/ftrace.c | 45 +++++++++++++++++++++++++++++------ arch/arm/kernel/module-plts.c | 44 ++++++++++++++++++++++++++++++---- 4 files changed, 82 insertions(+), 11 deletions(-)

diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h index 22b73112b75f..1c30be0f5dd0 100644 --- a/arch/arm/include/asm/ftrace.h +++ b/arch/arm/include/asm/ftrace.h @@ -14,6 +14,9 @@ struct dyn_arch_ftrace { #ifdef CONFIG_OLD_MCOUNT bool old_mcount; #endif +#ifdef CONFIG_ARM_MODULE_PLTS + struct module *mod; +#endif };

static inline unsigned long ftrace_call_adjust(unsigned long addr) diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h index 2e9872a22359..3cfbe8181224 100644 --- a/arch/arm/include/asm/module.h +++ b/arch/arm/include/asm/module.h @@ -29,6 +29,7 @@ struct plt_entries {

struct mod_plt_sec { struct elf32_shdr *plt; + struct plt_entries *plt_ent; int plt_count; };

diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c index a95bc0a02fd8..b1cf37fec354 100644 --- a/arch/arm/kernel/ftrace.c +++ b/arch/arm/kernel/ftrace.c @@ -95,9 +95,10 @@ int ftrace_arch_code_modify_post_process(void) return 0; }

-static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr) +static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr, + bool warn) { - return arm_gen_branch_link(pc, addr, true); + return arm_gen_branch_link(pc, addr, warn); }

static int ftrace_modify_code(unsigned long pc, unsigned long old, @@ -136,14 +137,14 @@ int ftrace_update_ftrace_func(ftrace_func_t func) int ret;

pc = (unsigned long)&ftrace_call; - new = ftrace_call_replace(pc, (unsigned long)func); + new = ftrace_call_replace(pc, (unsigned long)func, true);

ret = ftrace_modify_code(pc, 0, new, false);

#ifdef CONFIG_OLD_MCOUNT if (!ret) { pc = (unsigned long)&ftrace_call_old; - new = ftrace_call_replace(pc, (unsigned long)func); + new = ftrace_call_replace(pc, (unsigned long)func, true);

ret = ftrace_modify_code(pc, 0, new, false); } @@ -156,9 +157,21 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) { unsigned long new, old; unsigned long ip = rec->ip; + unsigned long aaddr = adjust_address(rec, addr); + struct module *mod = NULL; + +#ifdef CONFIG_ARM_MODULE_PLTS + mod = rec->arch.mod; +#endif

old = ftrace_nop_replace(rec); - new = ftrace_call_replace(ip, adjust_address(rec, addr)); + new = ftrace_call_replace(ip, aaddr, !mod); +#ifdef CONFIG_ARM_MODULE_PLTS + if (!new && mod) { + aaddr = get_module_plt(mod, ip, aaddr); + new = ftrace_call_replace(ip, aaddr, true); + } +#endif

return ftrace_modify_code(rec->ip, old, new, true); } @@ -166,12 +179,29 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec, unsigned long addr) { + unsigned long aaddr = adjust_address(rec, addr); unsigned long ip = rec->ip; unsigned long old; unsigned long new; int ret;

- old = ftrace_call_replace(ip, adjust_address(rec, addr)); +#ifdef CONFIG_ARM_MODULE_PLTS + /* mod is only supplied during module loading */ + if (!mod) + mod = rec->arch.mod; + else + rec->arch.mod = mod; +#endif + + old = ftrace_call_replace(ip, aaddr, + !IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || !mod); +#ifdef CONFIG_ARM_MODULE_PLTS + if (!old && mod) { + aaddr = get_module_plt(mod, ip, aaddr); + old = ftrace_call_replace(ip, aaddr, true); + } +#endif + new = ftrace_nop_replace(rec); ret = ftrace_modify_code(ip, old, new, true);

@@ -179,7 +209,8 @@ int ftrace_make_nop(struct module *mod, if (ret == -EINVAL && addr == MCOUNT_ADDR) { rec->arch.old_mcount = true;

- old = ftrace_call_replace(ip, adjust_address(rec, addr)); + old = ftrace_call_replace(ip, adjust_address(rec, addr), + !IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || !mod); new = ftrace_nop_replace(rec); ret = ftrace_modify_code(ip, old, new, true); } diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c index f272711c411f..6804a145be11 100644 --- a/arch/arm/kernel/module-plts.c +++ b/arch/arm/kernel/module-plts.c @@ -7,6 +7,7 @@ */

#include <linux/elf.h> +#include <linux/ftrace.h> #include <linux/kernel.h> #include <linux/module.h> #include <linux/sort.h> @@ -22,19 +23,52 @@ (PLT_ENT_STRIDE - 8)) #endif

+static const u32 fixed_plts[] = { +#ifdef CONFIG_FUNCTION_TRACER + FTRACE_ADDR, + MCOUNT_ADDR, +#endif +}; + static bool in_init(const struct module *mod, unsigned long loc) { return loc - (u32)mod->init_layout.base < mod->init_layout.size; }

+static void prealloc_fixed(struct mod_plt_sec *pltsec, struct plt_entries *plt) +{ + int i; + + if (!ARRAY_SIZE(fixed_plts) || pltsec->plt_count) + return; + pltsec->plt_count = ARRAY_SIZE(fixed_plts); + + for (i = 0; i < ARRAY_SIZE(plt->ldr); ++i) + plt->ldr[i] = PLT_ENT_LDR; + + BUILD_BUG_ON(sizeof(fixed_plts) > sizeof(plt->lit)); + memcpy(plt->lit, fixed_plts, sizeof(fixed_plts)); +} + u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val) { struct mod_plt_sec *pltsec = !in_init(mod, loc) ? &mod->arch.core : &mod->arch.init; + struct plt_entries *plt; + int idx; + + /* cache the address, ELF header is available only during module load */ + if (!pltsec->plt_ent) + pltsec->plt_ent = (struct plt_entries *)pltsec->plt->sh_addr; + plt = pltsec->plt_ent;

- struct plt_entries *plt = (struct plt_entries *)pltsec->plt->sh_addr; - int idx = 0; + prealloc_fixed(pltsec, plt); + + for (idx = 0; idx < ARRAY_SIZE(fixed_plts); ++idx) + if (plt->lit[idx] == val) + return (u32)&plt->ldr[idx];

+ idx = 0; /* * Look for an existing entry pointing to 'val'. Given that the * relocations are sorted, this will be the last entry we allocated. @@ -182,8 +216,8 @@ static unsigned int count_plts(const Elf32_Sym *syms, Elf32_Addr base, int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, char *secstrings, struct module *mod) { - unsigned long core_plts = 0; - unsigned long init_plts = 0; + unsigned long core_plts = ARRAY_SIZE(fixed_plts); + unsigned long init_plts = ARRAY_SIZE(fixed_plts); Elf32_Shdr *s, *sechdrs_end = sechdrs + ehdr->e_shnum; Elf32_Sym *syms = NULL;

@@ -238,6 +272,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, mod->arch.core.plt->sh_size = round_up(core_plts * PLT_ENT_SIZE, sizeof(struct plt_entries)); mod->arch.core.plt_count = 0; + mod->arch.core.plt_ent = NULL;

mod->arch.init.plt->sh_type = SHT_NOBITS; mod->arch.init.plt->sh_flags = SHF_EXECINSTR | SHF_ALLOC; @@ -245,6 +280,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs, mod->arch.init.plt->sh_size = round_up(init_plts * PLT_ENT_SIZE, sizeof(struct plt_entries)); mod->arch.init.plt_count = 0; + mod->arch.init.plt_ent = NULL;

pr_debug("%s: plt=%x, init.plt=%x\n", __func__, mod->arch.core.plt->sh_size, mod->arch.init.plt->sh_size);

-- 2.25.1

Florian Fainelli

9:03 p.m.

New subject: [PATCH stable 4.9 v3 4/4] ARM: 9098/1: ftrace: MODULE_PLT: Fix build problem without DYNAMIC_FTRACE

From: Alex Sverdlin alexander.sverdlin@nokia.com

commit 6fa630bf473827aee48cbf0efbbdf6f03134e890 upstream

FTRACE_ADDR is only defined when CONFIG_DYNAMIC_FTRACE is defined, the latter is even stronger requirement than CONFIG_FUNCTION_TRACER (which is enough for MCOUNT_ADDR).

Link: https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/ZUVCQBHD...

Fixes: 1f12fb25c5c5d22f ("ARM: 9079/1: ftrace: Add MODULE_PLTS support") Reported-by: kernel test robot lkp@intel.com Signed-off-by: Alexander Sverdlin alexander.sverdlin@nokia.com Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: Florian Fainelli f.fainelli@gmail.com --- arch/arm/kernel/module-plts.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c index 6804a145be11..ed0e09cc735f 100644 --- a/arch/arm/kernel/module-plts.c +++ b/arch/arm/kernel/module-plts.c @@ -24,7 +24,7 @@ #endif

static const u32 fixed_plts[] = { -#ifdef CONFIG_FUNCTION_TRACER +#ifdef CONFIG_DYNAMIC_FTRACE FTRACE_ADDR, MCOUNT_ADDR, #endif

-- 2.25.1

Greg Kroah-Hartman

4 Oct 4 Oct

11:08 a.m.

On Mon, Sep 27, 2021 at 02:03:12PM -0700, Florian Fainelli wrote:

...

This patch series is present in v5.14 and fixes warnings seen at insmod with FTRACE and MODULE_PLTS enabled on ARM/Linux.

Changes in v3:

resolved build error with allmodconfig enabling CONFIG_OLD_MCOUNT

All now queued up again.

thanks,

greg k-h

1178

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Florian Fainelli
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