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authorAlex Sverdlin <alexander.sverdlin@nokia.com>2021-05-05 08:59:04 +0200
committerRussell King (Oracle) <rmk+kernel@armlinux.org.uk>2021-06-07 13:56:20 +0200
commit79f32b221b18c15a98507b101ef4beb52444cc6f (patch)
tree03937a6086d0e119adb9391c7cc36425b99bffa5 /arch/arm/kernel/module-plts.c
parentARM: 9078/1: Add warn suppress parameter to arm_gen_branch_link() (diff)
downloadlinux-79f32b221b18c15a98507b101ef4beb52444cc6f.tar.xz
linux-79f32b221b18c15a98507b101ef4beb52444cc6f.zip
ARM: 9079/1: ftrace: Add MODULE_PLTS support
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>
Diffstat (limited to 'arch/arm/kernel/module-plts.c')
-rw-r--r--arch/arm/kernel/module-plts.c44
1 files changed, 40 insertions, 4 deletions
diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c
index d330e9ec2de3..a0524ad84e4d 100644
--- a/arch/arm/kernel/module-plts.c
+++ b/arch/arm/kernel/module-plts.c
@@ -4,6 +4,7 @@
*/
#include <linux/elf.h>
+#include <linux/ftrace.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sort.h>
@@ -20,19 +21,52 @@
(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.
@@ -180,8 +214,8 @@ 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;
@@ -236,6 +270,7 @@ 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;
@@ -243,6 +278,7 @@ 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);