[SFrame-V3] include: gas: libsframe: add 8-bits of func_info2 for extensibility in FDE

The existing field func_info (in the SFrame FDE) is used to convey important information around the encoding and interpretation of the rest of the stack trace data for the respective SFrame FDE: the SFrame FRE type, SFrame FDE PC type, etc. Currently there is 1 bit left for AArch64, and 2 bits for AMD64, s390x (and other future ABIs to be supported). Provision some additional space now (specifically an additional 8-bits) for future needs for V3 and beyond. Compared to V2, this now increases the size of SFrame FDE by 1 byte in V3. In this patch, the additional func_info2 byte is not used functionally yet. Hence, rather mechanical changes in libsframe, bfd and libsframe/testsuite accompany. We will put func_info2 into use in a later patch by reserving 5 of these bits for SFrame FDE types. With the addition of a new byte for additional func info (func_info2), add a new arg to allow usecases like textual dumper to get all data members in one API: sframe_decoder_get_funcdesc_v3. To keep the APIs symmetric looking, add new arg to sframe_encoder_add_funcdesc_v3 too. Since bfd uses these APIs, carry out the mechanical change in the respective APIs too. And of course, the testsuite which exercises these APIs. bfd/ * elf-sframe.c (_bfd_elf_merge_section_sframe): Get and set func_info2. * elf64-s390.c (_bfd_s390_elf_create_sframe_plt): Pass 0 for func_info2 for SFrame FDE for PLT. * elfxx-x86.c (_bfd_x86_elf_create_sframe_plt): Likewise. gas/ * gen-sframe.c (output_sframe_funcdesc): Emit the uint8_t for func_info2. libsframe/ * sframe-dump.c (dump_sframe_func_with_fres): * sframe.c (sframe_fde_tbl_init): Handle the new additional member. (sframe_encoder_write_fde): Likewise. * sframe.c (sframe_decoder_get_funcdesc_v3): Update func_info2. libsframe/testsuite/ * libsframe.decode/DATA2: Update data file with SFrame section data. * libsframe.encode/encode-1.c: Pass 0 for func_info2 arg. * libsframe.find/findfre-1.c: Likewise. * libsframe.find/findfunc-1.c: Likewise. * libsframe.find/plt-findfre-1.c: Likewise. * libsframe.find/plt-findfre-2.c: Likewise. include/ * sframe.h: Add new uint8_t sfde_func_info2 to sframe_func_desc_entry_v3. * sframe-api.h (sframe_decoder_get_funcdesc_v3): New arg. (sframe_encoder_add_funcdesc_v3): Likewise.
2026-02-05 09:01:31 +00:00 · 2026-01-15 16:42:17 -08:00
parent 5ed153a90a
commit c953fe86fa
14 changed files with 44 additions and 15 deletions
--- a/bfd/elf-sframe.c
+++ b/bfd/elf-sframe.c
@@ -488,6 +488,7 @@ _bfd_elf_merge_section_sframe (bfd *abfd,
      bfd_vma address;
      uint32_t func_size = 0;
      unsigned char func_info = 0;
+      unsigned char func_info2 = 0;
      unsigned int r_offset = 0;
      bool pltn_reloc_by_hand = false;
      unsigned int pltn_r_offset = 0;
@@ -495,7 +496,7 @@ _bfd_elf_merge_section_sframe (bfd *abfd,

      if (!sframe_decoder_get_funcdesc_v3 (sfd_ctx, i, &num_fres, &func_size,
 					   &func_start_addr, &func_info,
-					   &rep_block_size))
+					   &func_info2, &rep_block_size))
 	{
 	  /* If function belongs to a deleted section, skip editing the
 	     function descriptor entry.  */
@@ -562,7 +563,8 @@ _bfd_elf_merge_section_sframe (bfd *abfd,
 	  /* Update the encoder context with updated content.  */
 	  int err = sframe_encoder_add_funcdesc_v3 (sfe_ctx, func_start_addr,
 						    func_size, func_info,
-						    rep_block_size, num_fres);
+						    func_info2, rep_block_size,
+						    num_fres);
 	  cur_fidx++;
 	  BFD_ASSERT (!err);
 	}
--- a/bfd/elf64-s390.c
+++ b/bfd/elf64-s390.c
@@ -1616,6 +1616,7 @@ _bfd_s390_elf_create_sframe_plt (struct bfd_link_info *info)
 				      0, /* func start addr.  */
 				      plt0_entry_size,
 				      func_info,
+				      0, /* func_info2.  */
 				      0, /* Rep block size.  */
 				      0 /* Num FREs.  */);
      sframe_frame_row_entry plt0_fre;
@@ -1644,6 +1645,7 @@ _bfd_s390_elf_create_sframe_plt (struct bfd_link_info *info)
 				      plt0_entry_size, /* func start addr.  */
 				      dpltsec->size - plt0_entry_size,
 				      func_info,
+				      0, /* func_info2.  */
 				      plt_entry_size,
 				      0 /* Num FREs.  */);

--- a/bfd/elfxx-x86.c
+++ b/bfd/elfxx-x86.c
@@ -1917,6 +1917,7 @@ _bfd_x86_elf_create_sframe_plt (bfd *output_bfd,
 				      0, /* func start addr.  */
 				      plt0_entry_size,
 				      func_info,
+				      0, /* func_info2.  */
 				      0,
 				      0 /* Num FREs.  */);
      sframe_frame_row_entry plt0_fre;
@@ -1946,6 +1947,7 @@ _bfd_x86_elf_create_sframe_plt (bfd *output_bfd,
 				      plt0_entry_size, /* func start addr.  */
 				      dpltsec->size - plt0_entry_size,
 				      func_info,
+				      0, /* func_info2.  */
 				      plt_entry_size,
 				      0 /* Num FREs.  */);

--- a/gas/gen-sframe.c
+++ b/gas/gen-sframe.c
@@ -755,6 +755,7 @@ output_sframe_funcdesc (symbolS *start_of_fre_section,
  else
    out_one (func_info);
  out_one (0);
+  out_one (0);
 }

 static void
--- a/include/sframe-api.h
+++ b/include/sframe-api.h
@@ -182,7 +182,7 @@ sframe_decoder_get_funcdesc_v2 (const sframe_decoder_ctx *ctx,
 				unsigned char *func_info,
 				uint8_t *rep_block_size);

-/* Get the data (NUM_FRES, FUNC_SIZE, START_PC_OFFSET, FUNC_INFO,
+/* Get the data (NUM_FRES, FUNC_SIZE, START_PC_OFFSET, FUNC_INFO, FUNC_INFO2,
   REP_BLOCK_SIZE) from the SFrame function descriptor entry at the I'th index
   in the decoder object DCTX.  Return SFRAME_ERR on failure.  */
 extern int
@@ -192,6 +192,7 @@ sframe_decoder_get_funcdesc_v3 (const sframe_decoder_ctx *dctx,
 				uint32_t *func_size,
 				int64_t *start_pc_offset,
 				unsigned char *func_info,
+				unsigned char *func_info2,
 				uint8_t *rep_block_size);

 /* SFrame textual dump.  */
@@ -308,13 +309,14 @@ sframe_encoder_add_funcdesc_v2 (sframe_encoder_ctx *ectx,
 				uint32_t num_fres);

 /* Add a new SFrame function descriptor entry with START_PC_OFFSET, FUNC_SIZE,
-   FUNC_INFO and REP_BLOCK_SIZE to the encoder context ECTX.  Return error
-   code on failure.  */
+   FUNC_INFO, FUNC_INFO2 and REP_BLOCK_SIZE to the encoder context ECTX.
+   Return error code on failure.  */
 extern int
 sframe_encoder_add_funcdesc_v3 (sframe_encoder_ctx *ectx,
 				int64_t start_pc_offset,
 				uint32_t func_size,
 				unsigned char func_info,
+				unsigned char func_info2,
 				uint8_t rep_block_size,
 				uint32_t num_fres);

--- a/include/sframe.h
+++ b/include/sframe.h
@@ -269,6 +269,13 @@ typedef struct sframe_func_desc_entry_v3
     -------------------------------------------------------------------------------
     8        7             6                             5         4              0     */
  uint8_t sfde_func_info;
+  /* Additional information for stack tracing from the function:
+     - 8-bits: Unused.
+     ------------------------------------------------------------
+     |                         Unused                           |
+     ------------------------------------------------------------
+     8        7         6                         5             0     */
+  uint8_t sfde_func_info2;
  /* Size of the block of repeating insns.  Used for SFrame FDEs of type
     SFRAME_FDE_TYPE_PCMASK.  */
  uint8_t sfde_func_rep_size;
--- a/libsframe/sframe-dump.c
+++ b/libsframe/sframe-dump.c
@@ -148,7 +148,8 @@ dump_sframe_func_with_fres (const sframe_decoder_ctx *sfd_ctx,
      int64_t func_start_addr = 0;
      sframe_decoder_get_funcdesc_v3 (sfd_ctx, funcidx, &num_fres,
 				      &func_size, &func_start_addr,
-				      &func_info, &rep_block_size);
+				      &func_info, NULL,
+				      &rep_block_size);
      func_start_pc_vma = func_start_addr + sec_addr;
    }
  else
--- a/libsframe/sframe.c
+++ b/libsframe/sframe.c
@@ -34,6 +34,7 @@ typedef struct sframe_func_desc_entry_int
  uint32_t func_start_fre_off;
  uint32_t func_num_fres;
  uint8_t func_info;
+  uint8_t func_info2;
  uint8_t func_rep_size;
 } sframe_func_desc_entry_int;

@@ -153,6 +154,7 @@ sframe_fde_tbl_init (sf_fde_tbl *fde_tbl, const char *fde_buf,
 	  fde_tbl->entry[i].func_start_fre_off = fdep->sfde_func_start_fre_off;
 	  fde_tbl->entry[i].func_num_fres = fdep->sfde_func_num_fres;
 	  fde_tbl->entry[i].func_info = fdep->sfde_func_info;
+	  fde_tbl->entry[i].func_info2 = fdep->sfde_func_info2;
 	  fde_tbl->entry[i].func_rep_size = fdep->sfde_func_rep_size;
 	}
      fde_tbl->count = num_fdes;
@@ -172,6 +174,7 @@ sframe_fde_tbl_init (sf_fde_tbl *fde_tbl, const char *fde_buf,
 	  fde_tbl->entry[i].func_start_fre_off = fdep->sfde_func_start_fre_off;
 	  fde_tbl->entry[i].func_num_fres = fdep->sfde_func_num_fres;
 	  fde_tbl->entry[i].func_info = fdep->sfde_func_info;
+	  fde_tbl->entry[i].func_info2 = 0;
 	  fde_tbl->entry[i].func_rep_size = fdep->sfde_func_rep_size;
 	}
      fde_tbl->count = num_fdes;
@@ -1537,6 +1540,7 @@ sframe_decoder_get_funcdesc_v3 (const sframe_decoder_ctx *dctx,
 				uint32_t *func_size,
 				int64_t *start_pc_offset,
 				unsigned char *func_info,
+				unsigned char *func_info2,
 				uint8_t *rep_block_size)
 {
  int err = 0;
@@ -1556,6 +1560,8 @@ sframe_decoder_get_funcdesc_v3 (const sframe_decoder_ctx *dctx,
    *func_size = fdp->func_size;
  if (func_info)
    *func_info = fdp->func_info;
+  if (func_info2)
+    *func_info2 = fdp->func_info2;
  if (rep_block_size)
    *rep_block_size = fdp->func_rep_size;

@@ -1988,14 +1994,15 @@ sframe_encoder_add_funcdesc_v2 (sframe_encoder_ctx *ectx,
 }

 /* Add a new SFrame function descriptor entry with START_PC_OFFSET, FUNC_SIZE,
-   FUNC_INFO and REP_BLOCK_SIZE to the encoder context ECTX.  Return error
-   code on failure.  */
+   FUNC_INFO, FUNC_INFO2 and REP_BLOCK_SIZE to the encoder context ECTX.
+   Return error code on failure.  */

 int
 sframe_encoder_add_funcdesc_v3 (sframe_encoder_ctx *ectx,
 				int64_t start_pc_offset,
 				uint32_t func_size,
 				unsigned char func_info,
+				unsigned char func_info2,
 				uint8_t rep_block_size,
 				uint32_t num_fres ATTRIBUTE_UNUSED)
 {
@@ -2013,6 +2020,7 @@ sframe_encoder_add_funcdesc_v3 (sframe_encoder_ctx *ectx,

  sf_fde_tbl *fd_info = ectx->sfe_funcdesc;
  fd_info->entry[fd_info->count-1].func_info = func_info;
+  fd_info->entry[fd_info->count-1].func_info2 = func_info2;
  fd_info->entry[fd_info->count-1].func_rep_size = rep_block_size;

  return 0;
@@ -2142,6 +2150,7 @@ sframe_encoder_write_fde (const sframe_header *sfhp ATTRIBUTE_UNUSED,
  fdep->sfde_func_start_fre_off = fde->func_start_fre_off;
  fdep->sfde_func_num_fres = (uint16_t)fde->func_num_fres;
  fdep->sfde_func_info = fde->func_info;
+  fdep->sfde_func_info2 = fde->func_info2;
  fdep->sfde_func_rep_size = fde->func_rep_size;

  *fde_write_size = sizeof (sframe_func_desc_entry_v3);
--- a/libsframe/testsuite/libsframe.decode/DATA2
+++ b/libsframe/testsuite/libsframe.decode/DATA2
--- a/libsframe/testsuite/libsframe.encode/encode-1.c
+++ b/libsframe/testsuite/libsframe.encode/encode-1.c
@@ -40,7 +40,7 @@ add_fde1 (sframe_encoder_ctx *encode, int64_t start_pc_vaddr,
  unsigned char finfo = sframe_fde_create_func_info (SFRAME_FRE_TYPE_ADDR1,
 						     SFRAME_FDE_TYPE_PCINC);
  int err = sframe_encoder_add_funcdesc_v3 (encode, func1_start_addr,
-					    *func_size, finfo, 0,
+					    *func_size, finfo, 0, 0,
 					    FDE1_NUM_FRES);
  if (err == -1)
    return err;
@@ -76,7 +76,7 @@ add_fde2 (sframe_encoder_ctx *encode, int64_t start_pc_vaddr,
  unsigned char finfo = sframe_fde_create_func_info (SFRAME_FRE_TYPE_ADDR1,
 						     SFRAME_FDE_TYPE_PCINC);
  int err = sframe_encoder_add_funcdesc_v3 (encode, func1_start_addr,
-					    *func_size, finfo, 0,
+					    *func_size, finfo, 0, 0,
 					    FDE1_NUM_FRES);
  if (err == -1)
    return err;
--- a/libsframe/testsuite/libsframe.find/findfre-1.c
+++ b/libsframe/testsuite/libsframe.find/findfre-1.c
@@ -40,7 +40,7 @@ add_fde1 (sframe_encoder_ctx *encode, int64_t start_pc_vaddr,
  unsigned char finfo = sframe_fde_create_func_info (SFRAME_FRE_TYPE_ADDR1,
 						     SFRAME_FDE_TYPE_PCINC);
  int err = sframe_encoder_add_funcdesc_v3 (encode, func1_start_addr,
-					    *func_size, finfo, 0,
+					    *func_size, finfo, 0, 0,
 					    FDE1_NUM_FRES);
  if (err == -1)
    return err;
@@ -75,7 +75,7 @@ add_fde2 (sframe_encoder_ctx *encode, int64_t start_pc_vaddr,
  unsigned char finfo = sframe_fde_create_func_info (SFRAME_FRE_TYPE_ADDR1,
 						     SFRAME_FDE_TYPE_PCINC);
  int err = sframe_encoder_add_funcdesc_v3 (encode, func2_start_addr,
-					    *func_size, finfo, 0,
+					    *func_size, finfo, 0, 0,
 					    FDE2_NUM_FRES);
  if (err == -1)
    return err;
--- a/libsframe/testsuite/libsframe.find/findfunc-1.c
+++ b/libsframe/testsuite/libsframe.find/findfunc-1.c
@@ -47,7 +47,7 @@ add_fde1 (sframe_encoder_ctx *encode, int64_t start_pc_vaddr,
  unsigned char finfo = sframe_fde_create_func_info (SFRAME_FRE_TYPE_ADDR1,
 						     SFRAME_FDE_TYPE_PCINC);
  int err = sframe_encoder_add_funcdesc_v3 (encode, func1_start_addr,
-					    *func_size, finfo, 0,
+					    *func_size, finfo, 0, 0,
 					    FDE1_NUM_FRES);
  if (err == -1)
    return err;
@@ -82,7 +82,7 @@ add_fde2 (sframe_encoder_ctx *encode, int64_t start_pc_vaddr,
  unsigned char finfo = sframe_fde_create_func_info (SFRAME_FRE_TYPE_ADDR1,
 						     SFRAME_FDE_TYPE_PCINC);
  int err = sframe_encoder_add_funcdesc_v3 (encode, func2_start_addr,
-					    *func_size, finfo, 0,
+					    *func_size, finfo, 0, 0,
 					    FDE2_NUM_FRES);
  if (err == -1)
    return err;
@@ -117,7 +117,7 @@ add_fde3 (sframe_encoder_ctx *encode, int64_t start_pc_vaddr,
  unsigned char finfo = sframe_fde_create_func_info (SFRAME_FRE_TYPE_ADDR1,
 						     SFRAME_FDE_TYPE_PCINC);
  int err = sframe_encoder_add_funcdesc_v3 (encode, func3_start_addr,
-					    *func_size, finfo, 0,
+					    *func_size, finfo, 0, 0,
 					    FDE3_NUM_FRES);
  if (err == -1)
    return err;
--- a/libsframe/testsuite/libsframe.find/plt-findfre-1.c
+++ b/libsframe/testsuite/libsframe.find/plt-findfre-1.c
@@ -41,6 +41,7 @@ add_plt_fde1 (sframe_encoder_ctx *ectx, int64_t plt_vaddr,
  int err = sframe_encoder_add_funcdesc_v3 (ectx, func_start_addr,
 					    16 * 5 /* func size in bytes.  */,
 					    finfo,
+					    0, /* func_info2.  */
 					    16 /* rep block size in bytes.  */,
 					    PLT1_NUM_FRES);
  if (err == -1)
--- a/libsframe/testsuite/libsframe.find/plt-findfre-2.c
+++ b/libsframe/testsuite/libsframe.find/plt-findfre-2.c
@@ -48,6 +48,7 @@ add_plt0_fde (sframe_encoder_ctx *ectx, int64_t plt_vaddr,
  int err = sframe_encoder_add_funcdesc_v3 (ectx, func_start_addr,
 					    PLT_SIZE /* func size.  */,
 					    finfo,
+					    0, /* func_info2.  */
 					    0 /* rep block size.  */,
 					    1 /* num FREs.  */);
  if (err == -1)
@@ -81,6 +82,7 @@ add_pltn_fde (sframe_encoder_ctx *ectx, int64_t plt_vaddr,
  int err = sframe_encoder_add_funcdesc_v3 (ectx, func_start_addr,
 					    5 * PLT_SIZE /* func size.  */,
 					    finfo,
+					    0, /* func_info2.  */
 					    PLT_SIZE /* rep block size.  */,
 					    1 /* num FREs.  */);
  if (err == -1)